ORCID Profile
0000-0003-2493-5209
Current Organisation
Monash University
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Research Topics
In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Top 5 Research Topics
ANZSRC Field of Research (FoR)
Analytical Chemistry | Electrochemistry | Electroanalytical Chemistry | Sensor (Chemical And Bio-) Technology | Electroanalytical Chemistry | Physical Chemistry (Incl. Structural) | Catalysis and mechanisms of reactions | Catalytic Process Engineering | Macromolecular and Materials Chemistry | Synthesis of Materials | Electrochemistry | Electrochemistry | Functional materials | Physical chemistry | Nanomanufacturing | Carbon capture engineering (excl. sequestration) | Chemical and thermal processes in energy and combustion | Chemical engineering | Functional Materials | Bioprocessing bioproduction and bioproducts | Electrochemical energy storage and conversion
ANZSRC Socio-Economic Objective (SEO)
Expanding Knowledge in the Chemical Sciences | Diagnostic methods | Expanding Knowledge in Technology | Expanding Knowledge in the Information and Computing Sciences | Chemical sciences | Scientific instrumentation | Energy transformation not elsewhere classified | Energy Storage (excl. Hydrogen) | Expanding Knowledge in the Biological Sciences |
Related Links
Publications
Enhanced NADH Oxidation Using Polytyramine/Carbon Nanotube Modified Electrodes for Ethanol Biosensing
Publisher: Wiley
Date: 26-05-2017
Comparison of fast electron transfer kinetics at platinum, gold, glassy carbon and diamond electrodes using Fourier-transformed AC voltammetry and scanning electrochemical microscopy
Publisher: Royal Society of Chemistry (RSC)
Date: 2017
DOI: 10.1039/C7CP00968B
Abstract: Complementary techniques reveal new insights on electron transfer rates at different electrode materials.
Effect of Triton X-100 on electron transfer kinetics at the interface between two immiscible electrolyte solutions: a scanning electrochemical microscopy study
Publisher: Elsevier BV
Date: 12-2000
Large amplitude fourier transformed AC voltammetric investigation of the active state electrochemistry of a copper/aqueous base interface and implications for electrocatalysis
Publisher: American Chemical Society (ACS)
Date: 20-07-2011
DOI: 10.1021/LA2017819
Abstract: The higher harmonic components available from large- litude Fourier-transformed alternating current (FT-ac) voltammetry enable the surface active state of a copper electrode in basic media to be probed in much more detail than possible with previously used dc methods. In particular, the absence of capacitance background current allows low-level Faradaic current contributions of fast electron-transfer processes to be detected these are usually completely undetectable under conditions of dc cyclic voltammetry. Under high harmonic FT-ac voltammetric conditions, copper electrodes exhibit well-defined and reversible premonolayer oxidation responses at potentials within the double layer region in basic 1.0 M NaOH media. This process is attributed to oxidation of copper adatoms (Cu*) of low bulk metal lattice coordination numbers to surface-bonded, reactive hydrated oxide species. Of further interest is the observation that cathodic polarization in 1.0 M NaOH significantly enhances the current detected in each of the fundamental to sixth FT-ac harmonic components in the Cu*/Cu hydrous oxide electron-transfer process which enables the underlying electron transfer processes in the higher harmonics to be studied under conditions where the dc capacitance response is suppressed the results support the incipient hydrous oxide adatom mediator (IHOAM) model of electrocatalysis. The underlying quasi-reversible interfacial Cu*/Cu hydrous oxide process present under these conditions is shown to mediate the reduction of nitrate at a copper electrode, while the mediator for the hydrazine oxidation reaction appears to involve a different mediator or active state redox couple. Use of FT-ac voltammetry offers prospects for new insights into the nature of active sites and electrocatalysis at the electrode/solution interface of Group 11 metals in aqueous media.
Studies on monoxide emission spectrometry of rare earth elementsPart V.† Determination of Dy in rare earth concentrates by dual wavelength method
Publisher: Royal Society of Chemistry (RSC)
Date: 1998
DOI: 10.1039/A708895G
Demonstration of Superiority of the Marcus-Hush Electrode Kinetic Model in the Electrochemistry of Dissolved Decamethylferrocene at a Gold-Modified Electrode by Fourier-Transformed Alternating Current Voltammetry
Publisher: American Chemical Society (ACS)
Date: 04-04-2018
Fourier Transformed Large Amplitude Alternating Current Voltammetry: Principles and Applications
Publisher: The Polarographic Society of Japan
Date: 2015
Does delirium prevention reduce risk of in-patient falls among older adults? A systematic review and trial sequential meta-analysis.
Publisher: Wiley
Date: 08-03-2022
DOI: 10.1111/AJAG.13051
Abstract: To determine whether delirium prevention interventions reduce the risk of falls among older hospitalised patients. A systematic search of health-care databases was undertaken. Given the frequency of small s le sized trials, a trial sequential meta-analysis was conducted to present estimate summary effects to date. A Bayesian approach was used to estimate the posterior probability of the delirium prevention interventions reducing falls risk by various clinically relevant levels. Five randomised controlled trials were included in our final meta-analysis. There was a 43% reduction in the risk of falls among participants in the delirium prevention intervention arm, compared to the control however, confidence intervals were wide (RE RR = 0.57, 95% CI 0.32 1.00, p = 0.05). This result was found to be statistically significant, according to traditional significance levels (z > 1.96) and the more conservative trial sequential analysis monitoring boundaries. The posterior probabilities of the delirium prevention intervention reducing the risk of falls by 10%, 20% and 30% were 0.86, 0.63 and 0.29 respectively. The results of this systematic review and trial sequential meta-analysis suggest that delirium prevention trials may reduce the risk of in-hospital falls among older patients by 43%. However, despite significant risk reduction found upon meta-analysis, the variation among study populations and intervention components raised questions around its application in clinical practice. Further research is required to investigate what the necessary components of a multifactorial intervention are to reduce both delirium and fall incidence among older adult in-patients.
Can Electrification of Ammonia Synthesis Decrease Its Carbon Footprint?
Publisher: Elsevier BV
Date: 2020
One pot synthesis of poly(5-hydroxyl-1,4-naphthoquinone) stabilized gold nanoparticles using the monomer as the reducing agent for nonenzymatic electrochemical detection of glucose
Publisher: Elsevier BV
Date: 2015
Theoretical and experimental evaluation of screen-printed tubular carbon ink disposable sensor well electrodes by dc and Fourier transformed ac voltammetry
Publisher: Springer Science and Business Media LLC
Date: 23-12-2009
Phosphomolybdate@poly(diallyldimethylammonium chloride)-reduced graphene oxide modified electrode for highly efficient electrocatalytic reduction of bromate
Publisher: Elsevier BV
Date: 08-2014
Stabilization of Low‐Valent Iron(I) in a High‐Valent Vanadium(V) Oxide Cluster
Publisher: Wiley
Date: 09-10-2017
Abstract: Low-valent iron centers are critical intermediates in chemical and bio-chemical processes. Herein, we show the first ex le of a low-valent Fe
Hydrophobicity Graded Gas Diffusion Layer for Stable Electrochemical Reduction of CO2
Publisher: Wiley
Date: 23-08-2022
Abstract: To mitigate flooding associated with the gas diffusion layer (GDL) during electroreduction of CO 2 , we report a hydrophobicity‐graded hydrophobic GDL (HGGDL). Coating uniformly dispersed polytetrafluoroethylene (PTFE) binders on the carbon fiber skeleton of a hydrophilic GDL uniformizes the hydrophobicity of the GDL and also alleviates the gas blockage of pore channels. Further adherence of the PTFE macroporous layer (PMPL) to one side of the hydrophobic carbon fiber skeleton was aided by sintering. The introduced PMPL shows an appropriate pore size and enhanced hydrophobicity. As a result, the HGGDL offers spatial control of the hydrophobicity and hence water and gas transport over the GDL. Using a nickel‐single‐atom catalyst, the resulting HGGDL electrode provided a CO faradaic efficiency of over 83 % at a constant current density of 75 mA cm −2 for 103 h operation in a membrane electrode assembly, which is more than 16 times that achieved with a commercial GDL.
Two Tetra-CdII-Substituted Vanadogermanate Frameworks
Publisher: American Chemical Society (ACS)
Date: 21-03-2014
DOI: 10.1021/JA413218W
Abstract: Two new tetra-Cd(II)-substituted vanadogermanate frameworks {(CdX)4Ge8V(IV)10O46(H2O)[V(III)(H2O)2]4(GeO2)4}·8H2O (X = ethylenediamine (en, 1) and 1,2-diaminopropane (dap, 2)) were hydrothermally prepared and characterized by IR spectra, elemental analysis, powder X-ray diffraction (PXRD), energy-dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), and X-ray single-crystal diffraction. Both are isomorphic, and their 3-D frameworks are made up of tetra-Cd(II)-substituted {(CdX)4Ge8V(IV)10O46(H2O)}(12-) fundamental building units interconnected through planar tetra-V(III) [V(III)4O2(H2O)8](8-) clusters and tetrahedral GeO4 bridges. In the unique {(CdX)4Ge8V(IV)10O46(H2O)}(12-) cage, four [Ge2O7] dimers and four CdO4N2 trigonal prisms are alternately concatenated by μ3-O bridges to create a round {Ge8Cd4O28(X)4}(16-) fragment, five VO5 groups are linked by sharing edges to generate a pentanuclear [V5O17] subunit, and then the {Ge8Cd4O28(X)4}(16-) fragment is sandwiched by two V5O17 subunits via sharing O-atoms producing a D4h-symmetric {(CdX)4Ge8V(IV)10O46(H2O)}(12-) cage with a free water molecule located at the center. As we know, both display unprecedented 3-D organic-inorganic hybrid frameworks built up from the largest number of transition-metal-substituted vanadogermanate {(CdX)4Ge8V(IV)10O46}(12-) cluster shells linked by both GeO4 tetrahedra and rare [V(III)4O2(H2O)8](8-) clusters. Magnetic measurements reveal the antiferromagnetic couplings within the magnetic vanadium centers.
Facile electrochemical co-deposition of metal (Cu, Pd, Pt, Rh) nanoparticles on reduced graphene oxide for electrocatalytic reduction of nitrate/nitrite
Publisher: Elsevier BV
Date: 04-2018
Electrochemical reduction of aromatic ketones in 1-butyl-3-methylimidazolium-based ionic liquids in the presence of carbon dioxide: the influence of the ketone substituent and the ionic liquid anion o
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C5CP00095E
Abstract: The yield of electrocarboxylation of aromatic ketone depends on the imidazolium-based ionic liquid anion and the ketone substituent.
Application of power spectra patterns in Fourier transform square wave voltammetry to evaluate electrode kinetics of surface-confined proteins
Publisher: American Chemical Society (ACS)
Date: 25-03-2006
DOI: 10.1021/AC051823F
Abstract: This paper describes an application of Fourier transform (FT) voltammetry that provides a quantitative evaluation of the electron-transfer kinetics of protein molecules attached to electrode surfaces. The potential waveform applied in these experiments consists of a large- litude square wave of frequency f superimposed onto the traditional triangular voltage used in dc cyclic voltammetry. The resultant current-time response, when Fourier transformed into the frequency domain, provides patterns of data at the even harmonic frequencies that arise from nonlinearity in the Faradaic response. These even harmonic contributions are ideally suited for kinetic evaluation of electron-transfer processes because they are highly selective to quasi-reversible behavior (insensitive to reversible or irreversible processes) and almost devoid of background charging current. Inverse FT methods can then be used to provide the wave shapes of the dc as well as the ac voltammetric components and other characteristics employed to detect the level of nonideality present relative to theoretical models based upon noninteracting surface-confined molecules. The new form of data evaluation has been applied to the electron-transfer properties of a typical biological electron carrier, the blue copper protein azurin, immobilized on polycrystalline gold electrodes modified with self-assembled monolayers of different length alkanethiols. Details of the electrode kinetics (rates of electron transfer, dispersion, and charge-transfer coefficients) as a function of alkanethiol, apparent surface coverage, and capacitance are all deduced from the square wave (FT-inverse FT) protocol, and the implications of these findings are considered.
A Facile Chemical-Free and Universal Method for Transfer of Ultrathin Graphene-Based Films
Publisher: Wiley
Date: 08-08-2016
Electrocarboxylation of acetophenone in ionic liquids: the influence of proton availability on product distribution
Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C3GC42404A
Abstract: High-yield electrocarboxylation of acetophenone can be achieved in dry [BMPyrd][TFSI].
Electrode reaction and mass transport mechanisms associated with the iodide/triiodide couple in the ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide
Publisher: American Chemical Society (ACS)
Date: 23-09-2014
DOI: 10.1021/JP506990E
Large-Amplitude Fourier-Transformed AC Voltammetric Study of the Capacitive Electrochemical Behavior of the 1-Butyl-3-methylimidazolium Tetrafluoroborate-Polycrystalline Gold Electrode Interface
Publisher: American Chemical Society (ACS)
Date: 18-05-2017
Kinetics of bromine transfer across Langmuir monolayers of phosphatidylethanolamines at the water/air interface
Publisher: Royal Society of Chemistry (RSC)
Date: 2003
DOI: 10.1039/B306518A
Hierarchical Mesoporous SnO2 Nanosheets on Carbon Cloth: A Robust and Flexible Electrocatalyst for CO2 Reduction with High Efficiency and Selectivity
Publisher: Wiley
Date: 07-12-2016
Abstract: Electrochemical reduction of CO
Electrocatalytic CO2 Reduction to Formate on Cu Based Surface Alloys with Enhanced Selectivity
Publisher: American Chemical Society (ACS)
Date: 10-11-2019
Capturing the ‘art’ of emergency medicine: Does film foster reflection in medical students?
Publisher: Wiley
Date: 07-03-2017
Abstract: Integrating arts and humanities-based pedagogy into curricula is of growing interest among medical educators, particularly how it promotes reflection and empathy. Our aim was to explore whether a 2.50 min film titled 'The Art of the ED' stimulated reflective learning processes in a group of first year medical students. The film was shown prior to their first clinical placement in an ED. Student participation was voluntary and not assessable. Using an exploratory qualitative research approach, this study drew on data collected from students' in idual written reflections, exploring their perceptions towards clinical experience in an emergency medicine (EM) attachment. A total of 123 (51% of 240) students submitted a reflection. The qualitative data revealed three main themes: the opportunity for students to preview EM ('While watching the film, I felt like I was the patient and the doctor all at once, in that I was living the experience both from within and as an observer …') exposed the reality of ED and fostered a growing awareness of the fragility of human life. These findings highlight how visual methodologies (like film) create a safe, non-threatening space to access, experience and process emotion around their perceptions towards EM, and to anticipate and emotionally prepare for their impending clinical experience in the ED. These data support the use of visual methodologies to foster reflective processes that assist medical students to integrate the 'art' of EM, and the development and commitment of core doctoring values of empathy, service and respect for patients.
Electrode Material Dependence, Ion Pairing, and Progressive Increase in Complexity of the α-[S2W18O62]4–/5–/6–/7–/8–/9–/10– Reduction Processes in Acetonitr
Publisher: American Chemical Society (ACS)
Date: 23-06-2020
Effect of the N-based ligands in copper complexes for depolymerisation of lignin
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C5NJ03152D
Abstract: Several organic soluble N-based ligands and their copper complexes were firstly investigated as catalysts to depolymerise organosolv lignin in the organic solvent, dimethylformamide (DMF) and an ionic liquid (1-ethyl-3-methylimidazolium xylenesulfonate, [emim][ABS]).
Single-Boron Catalysts for Nitrogen Reduction Reaction
Publisher: American Chemical Society (ACS)
Date: 05-02-2019
DOI: 10.1021/JACS.8B13165
Abstract: Boron has been explored as p-block catalysts for nitrogen reduction reaction (NRR) by density functional theory. Unlike transition metals, on which the active centers need empty d orbitals to accept the lone-pair electrons of the nitrogen molecule, the sp
Impact of Adsorption on Scanning Electrochemical Microscopy Voltammetry and Implications for Nanogap Measurements
Publisher: American Chemical Society (ACS)
Date: 26-02-2016
DOI: 10.1021/ACS.ANALCHEM.5B04715
Abstract: Scanning electrochemical microscopy (SECM) is a powerful tool that enables quantitative measurements of fast electron transfer (ET) kinetics when coupled with modeling predictions from finite-element simulations. However, the advent of nanoscale and nanogap electrode geometries that have an intrinsically high surface area-to-solution volume ratio realizes the need for more rigorous data analysis procedures, as surface effects such as adsorption may play an important role. The oxidation of ferrocenylmethyl trimethylammonium (FcTMA(+)) at highly oriented pyrolytic graphite (HOPG) is used as a model system to demonstrate the effects of reversible reactant adsorption on the SECM response. Furthermore, the adsorption of FcTMA(2+) species onto glass, which is often used to encapsulate ultramicroelectrodes employed in SECM, is also found to be important and affects the voltammetric tip response in a nanogap geometry. If a researcher is unaware of such effects (which may not be readily apparent in slow to moderate scan voltammetry) and analyzes SECM data assuming simple ET kinetics at the substrate and an inert insulator support around the tip, the result is the incorrect assignment of tip-substrate heights, kinetics, and thermodynamic parameters. Thus, SECM kinetic measurements, particularly in a nanogap configuration where the ET kinetics are often very fast (only just distinguishable from reversible), require that such effects are fully characterized. This is possible by expanding the number of experimental variables, including the voltammetric scan rate and concentration of redox species, among others.
Reply to Comment on Stabilization of Low‐Valent Iron(I) in a High‐Valent Vanadium(V) Oxide Cluster
Publisher: Wiley
Date: 03-07-2019
Abstract: The authors of the Communication "Stabilization of Low-Valent Iron(I) in a High-Valent Vanadium(V) Oxide Cluster" reply to a Comment by Dr. Sproules, who offered an alternative interpretation of the metal oxidation states in the two electron reduced iron vanadate (NH
Porous nitrogen–doped carbon derived from biomass for electrocatalytic reduction of CO2 to CO
Publisher: Elsevier BV
Date: 08-2017
Efficient Enzymatic Oxidation of Glucose Mediated by Ferrocene Covalently Attached to Polyethylenimine Stabilized Gold Nanoparticles
Publisher: Wiley
Date: 15-07-2016
Selective Electrochemical Hydrogenation of Phenol with Earth‐abundant Ni−MoO2 Heterostructured Catalysts: Effect of Oxygen Vacancy on Product Selectivity
Publisher: Wiley
Date: 18-01-2023
Abstract: Herein, we report highly efficient carbon supported Ni−MoO 2 heterostructured catalysts for the electrochemical hydrogenation (ECH) of phenol in 0.10 M aqueous sulfuric acid (pH 0.7) at 60 °C. Highest yields for cyclohexanol and cyclohexanone of 95 % and 86 % with faradaic efficiencies of ∼50 % are obtained with catalysts bearing high and low densities of oxygen vacancy (O v ) sites, respectively. In situ diffuse reflectance infrared spectroscopy and density functional theory calculations reveal that the enhanced phenol adsorption strength is responsible for the superior catalytic efficiency. Furthermore, 1‐cyclohexene‐1‐ol is an important intermediate. Its hydrogenation route and hence the final product are affected by the O v density. This work opens a promising avenue to the rational design of advanced electrocatalysts for the upgrading of phenolic compounds.
Theoretical studies of large amplitude alternating current voltammetry for a reversible surface-confined electron transfer process coupled to a pseudo first-order electrocatalytic process
Publisher: Elsevier BV
Date: 02-2007
Cobalt(II) phosphonate coordination polymers: Synthesis, characterization and application as oxygen evolution electrocatalysts in aqueous media and water-saturated hydrophobic 1-butyl-3-methylimidazol
Publisher: Elsevier BV
Date: 07-2013
Electrocatalytic carbon dioxide reduction: from fundamental principles to catalyst design
Publisher: Elsevier BV
Date: 09-2020
Voltammetric studies with adhered microparticles and the detection of a dependence of organometallic Cis(+) -> trans(+) first-order isomerization rate constants on the identity of the ionic liquid
Publisher: American Chemical Society (ACS)
Date: 07-05-2004
DOI: 10.1021/JP049294R
Synthesis of Metallic Nanoparticles Using Electrogenerated Reduced Forms of [α-SiW12O40]4– as Both Reductants and Stabilizing Agents
Publisher: American Chemical Society (ACS)
Date: 04-10-2011
DOI: 10.1021/CM201166T
Electrochemical Hydrogenation of Furfural in Aqueous Acetic Acid Media with Enhanced 2-Methylfuran Selectivity Using CuPd Bimetallic Catalysts
Publisher: Wiley
Date: 03-02-2022
Abstract: Herein, we report a series of CuPd catalysts for electrochemical hydrogenation (ECH) of furfural to 2‐methylfuran (MF or FurCH 3 where Fur=furyl) in aqueous 0.1 M acetic acid (pH 2.9). The highest faradaic efficiency (FE) for MF reached 75 % at −0.58 V vs. reversible hydrogen electrode with an average partial current density of 4.5 mA cm −2 . In situ surface‐enhanced Raman spectroscopic and kinetic isotopic experiments suggested that electrogenerated adsorbed hydrogen (H ads ) was involved in the reaction and incorporation of Pd enhanced the surface coverage of H ads and optimized the adsorption pattern of furfural, leading to a higher FE for MF. Density functional theory calculations revealed that Pd incorporation reduced the energy barrier for the hydrogenation of FurCH 2 * to FurCH 3 *. Our study demonstrates that catalyst surface structure/composition plays a crucial role in determining the selectivity in ECH and provides a new strategy for designing advanced catalysts for ECH of bio‐derived oxygenates.
Measurement of the forward and back rate constants for electron transfer at the interface between two immiscible electrolyte solutions using scanning electrochemical microscopy (SECM): Theory and expe
Publisher: Elsevier BV
Date: 07-2001
Influence of Tip and Substrate Properties and Nonsteady-State Effects on Nanogap Kinetic Measurements: Response to Comment on Impact of Adsorption on Scanning Electrochemical Microscopy Voltammetry and Implications for Nanogap Measurements
Publisher: American Chemical Society (ACS)
Date: 23-06-2017
Stannate derived bimetallic nanoparticles for electrocatalytic CO2 reduction
Publisher: Royal Society of Chemistry (RSC)
Date: 2018
DOI: 10.1039/C8TA02429D
Abstract: Stannate derived bimetallic systems can achieve highly efficient electrocatalytic CO 2 reduction to formate.
Facile electrochemical co-deposition of a graphene–cobalt nanocomposite for highly efficient water oxidation in alkaline media: direct detection of underlying electron transfer reactions under catalyt
Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C4CP01608D
Abstract: Graphene–cobalt nanocomposite modified electrodes fabricated using a facile electrochemical co-deposition method exhibit high water oxidation efficiency in alkaline media.
Chapter 7. Electrocarboxylation in Ionic Liquids
Publisher: Royal Society of Chemistry
Date: 2018
Electrochemical Reduction of CO2 with an Oxide‐Derived Lead Nano‐Coralline Electrode in Dimcarb
Publisher: Wiley
Date: 04-04-2017
NiO Nanoparticles Anchored on Phosphorus‐Doped α‐Fe2O3 Nanoarrays: An Efficient Hole Extraction p–n Heterojunction Photoanode for Water Oxidation
Publisher: Wiley
Date: 13-06-2018
Abstract: The photoelectrochemical (PEC) water-splitting efficiency of a hematite-based photoanode is still far from the theoretical value due to its poor surface reaction kinetics and high density of surface trapping states. To solve these drawbacks, a photoanode consisting of NiO nanoparticles anchored on a gradient phosphorus-doped α-Fe
Voltammetric ion-selective electrodes for the selective determination of cations and anions
Publisher: American Chemical Society (ACS)
Date: 02-02-2010
DOI: 10.1021/AC902296R
Abstract: A general theory has been developed for voltammetric ion sensing of cations and anions based on the use of an electrode coated with a membrane containing an electroactive species, an ionophore, and a supporting electrolyte dissolved in a plasticizer. In experimental studies, a membrane coated electrode is fabricated by the drop coating method. In one configuration, a glassy carbon electrode is coated with a poly(vinyl chloride) based membrane, which contains the electroactive species, ionophore, plasticizer and supporting electrolyte. In the case of a cation sensor, ionophore facilitated transfer of the target cation from the aqueous solution to the membrane phase occurs during the course of the reduction of the electroactive species present in the membrane in order to maintain charge neutrality. The formal potential is calculated from the cyclic voltammogram as the average of the reduction and oxidation peak potentials and depends on the identity and concentration of the ion present in the aqueous solution phase. A plot of the formal potential versus the logarithm of the concentration exhibits a close to Nernstian slope of RT/F millivolts per decade change in concentration when the concentration of K(+) and Na(+) is varied over the concentration range of 0.1 mM to 1 M when K(+) or Na(+) ionophores are used in the membrane. The slope is close to RT/2F millivolts for a Ca(2+) voltammetric ion-selective electrode fabricated using a Ca(2+) ionophore. The sensor measurement time is only a few seconds. Voltammetric sensors for K(+), Na(+), and Ca(2+) constructed in this manner exhibit the sensitivity and selectivity required for determination of these ions in environmentally and biologically important matrixes. Analogous principles apply to the fabrication of anion voltammetric sensors.
Voltammetric Determination of the Iodide/Iodine Formal Potential and Triiodide Stability Constant in Conventional and Ionic Liquid Media
Publisher: American Chemical Society (ACS)
Date: 16-09-2015
Prevalence of SARS‐CoV‐2 antibodies among nurses: A systematic review and meta‐analysis
Publisher: Wiley
Date: 27-09-2021
DOI: 10.1111/JOCN.16009
Abstract: This systematic review and meta‐analysis reports the seroprevalence of SARS‐CoV‐2 antibodies among nurses. With a growing body of literature reporting the positive serology for SARS‐CoV‐2 antibodies among healthcare workers, it remains unclear whether staff at the point of direct patient care are more prone to developing and transmitting the virus. Given nurses make up the majority of the global health workforce, outbreaks among these workers could severely undermine a health system’s capability to manage the pandemic. We aimed to summarise and report the seroprevalence of SARS‐CoV‐2 antibodies among nurses globally. Systematic review and meta‐analyses. This systematic review was developed, undertaken and reported in accordance with the Preferred Reporting Items for Systematic Reviews and Meta‐Analyses (PRISMA) guideline. We searched the electronic medical literature databases: MEDLINE CINAHL and EMBASE for studies reporting the seroprevalence of SARS‐CoV‐2 antibodies among nursing staff. Studies that reported nursing specific data were included in this review. Study quality was evaluated using the Joanna Briggs Institute checklist for studies reporting prevalence data. Studies were stratified according to the World Health Organisation region classifications, and results were presented using forest plots and summary prevalence and variance was estimated using a random effects model. Our electronic search identified 1687 potential studies, of which 1148 were screened for eligibility after duplicates were removed, and 51 of the studies were included in our meta‐analysis. The overall seroprevalence of SARS‐CoV‐2 antibodies among nurses was estimated to be 8.1% (95% CI 6.9%–9.4%) among the 60,571 participants included in the studies. Seropositivity was highest in the African region (48.2%, 95% CI 39.2%–57.3%), followed by the European region (10.3%, 95% CI 8.0%–12.5%), the Region of the Americas (8.4%, 95% CI 6.0%–10.7%), the South‐East Asia region (3.0%, 95% CI 0.00%–6.5%) and the Western Pacific region (0.5%, 95% CI 0.0%–1.0%). Pooled estimates were unable to be calculated in the Eastern Mediterranean region due to insufficient studies. The seroprevalence of SARS‐CoV‐2 antibodies among nurses is comparable to other healthcare workers, and possibly similar to the general population. Early adoption and adherence to personal protective equipment and social distancing measures could explain these similarities, meaning the majority of staff contracted the virus through community transmission and not in a healthcare setting. Fear and uncertainty have been features of this pandemic, including among nurses. This meta‐analysis should provide some comfort to nurses that risks are similar to community exposure when adequate PPE is available and there is an adherence to infection control measures.
Synthesis, characterization, crystal structure, electrochemical properties and electrocatalytic activity of an unexpected nickel(II) Schiff base complex derived from bis(acetylacetonato)nickel(II), acetone and ethylenediamine
Publisher: Springer Science and Business Media LLC
Date: 07-09-2014
The solid-state Ag/AgCl process as a highly sensitive detection mechanism for an electrochemical immunosensor
Publisher: Royal Society of Chemistry (RSC)
Date: 2009
DOI: 10.1039/B910730D
Abstract: The highly characteristic solid-state Ag/AgCl process was used as an ultrasensitive detection mechanism for electrochemical sensors, such as a prostate-specific antigen immunosensor.
Modelling limitations encountered in the thermodynamic and electrode kinetic parameterization of the α-[S2W18O62]4−/5−/6− processes at glassy carbon and metal electrodes
Publisher: Elsevier BV
Date: 09-2020
Additions and corrections for Journal of Materials Chemistry C published 12th March 2014 to 25th June 2014
Publisher: Royal Society of Chemistry (RSC)
Date: 31-07-2014
DOI: 10.1039/C4TC90093F
Applications of convolution voltammetry in electroanalytical chemistry
Publisher: American Chemical Society (ACS)
Date: 04-02-2014
DOI: 10.1021/AC4036422
Abstract: The robustness of convolution voltammetry for determining accurate values of the diffusivity (D), bulk concentration (C(b)), and stoichiometric number of electrons (n) has been demonstrated by applying the technique to a series of electrode reactions in molecular solvents and room temperature ionic liquids (RTILs). In acetonitrile, the relatively minor contribution of nonfaradaic current facilitates analysis with macrodisk electrodes, thus moderate scan rates can be used without the need to perform background subtraction to quantify the diffusivity of iodide [D = 1.75 (±0.02) × 10(-5) cm(2) s(-1)] in this solvent. In the RTIL 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, background subtraction is necessary at a macrodisk electrode but can be avoided at a microdisk electrode, thereby simplifying the analytical procedure and allowing the diffusivity of iodide [D = 2.70 (±0.03) × 10(-7) cm(2) s(-1)] to be quantified. Use of a convolutive procedure which simultaneously allows D and nC(b) values to be determined is also demonstrated. Three conditions under which a technique of this kind may be applied are explored and are related to electroactive species which display slow dissolution kinetics, undergo a single multielectron transfer step, or contain multiple noninteracting redox centers using ferrocene in an RTIL, 1,4-dinitro-2,3,5,6-tetramethylbenzene, and an alkynylruthenium trimer, respectively, as ex les. The results highlight the advantages of convolution voltammetry over steady-state techniques such as rotating disk electrode voltammetry and microdisk electrode voltammetry, as it is not restricted by the mode of diffusion (planar or radial), hence removing limitations on solvent viscosity, electrode geometry, and voltammetric scan rate.
Separating the Effects of Experimental Noise from Inherent System Variability in Voltammetry: The [Fe(CN)6]3–/4– Process
Publisher: American Chemical Society (ACS)
Date: 19-12-2019
DOI: 10.1021/ACS.ANALCHEM.8B04238
Abstract: Recently, we introduced the use of techniques drawn from Bayesian statistics to recover kinetic and thermodynamic parameters from voltammetric data and were able to show that the technique of large litude ac voltammetry yielded significantly more accurate parameter values than the equivalent dc approach. In this paper, we build on this work to show that this approach allows us, for the first time, to separate the effects of random experimental noise and inherent system variability in voltammetric experiments. We analyze ten repeated experimental data sets for the [Fe(CN)
Identification of Mechanistic Subtleties that Apply to Voltammetric Studies at Boron-Doped Diamond Electrodes
Publisher: American Chemical Society (ACS)
Date: 22-10-2020
Investigations of Fast Electrode Kinetics for Reduction of 2,3,5,6-Tetrafluoro-7,7,8,8-tetracyanoquinodimethane in Conventional Solvents and Ionic Liquids Using Fourier Transformed Large Amplitude Alternating Current Voltammetry
Publisher: American Chemical Society (ACS)
Date: 23-04-2014
DOI: 10.1021/JP501862N
Novel Kinetic and Background Current Selectivity in the Even Harmonic Components of Fourier Transformed Square-Wave Voltammograms of Surface-Confined Azurin
Publisher: American Chemical Society (ACS)
Date: 14-04-2005
DOI: 10.1021/JP044614S
Abstract: Fourier transform analysis of r ed square-wave voltammograms indicates the availability of a novel form of kinetic selectivity for surface-confined electron-transfer processes. Thus, for all the even harmonic components, quasi-reversible processes are sensitive to the surface coverage, the reversible potential, the electron-transfer rate constant (k(0')), and the electron-transfer coefficient (alpha), as well as to the litude (DeltaE) and frequency (f) of the square wave and dc scan rate. Additionally, it is insensitive to background capacitance current. In contrast, reversible processes and background currents are predicted to be absent from the even harmonics and only detectable in the odd harmonic components. The square-wave voltammetry of the surface-confined quasi-reversible azurin process azurin[Cu(II)] + e(-) right arrow over left arrow azurin[Cu(I)] at a paraffin-impregnated graphite electrode has been employed as a model system to test theoretical predictions. Most voltammetric characteristics of the even harmonic components obtained from the Fourier analysis are consistent with electrode kinetic values of k(0') = 90 s(-1) and alpha = 0.48, although some nonideality possibly due to kinetic dispersion also is apparent. Conditions also have been determined under which a readily generated waveform constructed from the Fourier series of sine waves produces voltammograms that are essentially indistinguishable from those predicted when an ideal square wave is employed.
A Comparison of Bayesian Inference Strategies for Parameterisation of Large Amplitude AC Voltammetry Derived from Total Current and Fourier Transformed Versions
Publisher: Wiley
Date: 14-06-2021
Abstract: Use of carefully designed computer supported parameterisation methods in voltammetric studies can provide highly robust and accurate methods for simultaneously quantifying the large number of parameters present in complex electrochemical reactions. In this study, a computer program has been developed to parameterise large litude AC voltammetric data using mathematical optimisation in combination with Bayesian inference algorithms for calculating posterior distributions of parameters and hence uncertainties in parameter values. The computer program has been applied to objective functions, relevant to total AC current, frequency domain data in the form of the power spectrum derived from Fourier transformation and multivariate based methods using the resolved harmonic data. The robustness of the objective functions have been confirmed and Bayesian inference methods have been validated using “noisy” synthetic and experimental data for the [Fe(CN) 6 ] 3−/4− reduction process in aqueous 3.0 M KCl electrolyte at a gold electrode. It was found that the harmonic based Bayesian inference methods outperformed other methods in parameterisation of the thermodynamics and electrode kinetics of the close to reversible [Fe(CN) 6 ] 3−/4− process due to their ability to compensate for non‐ideality in the modelling and the superior parameter sensitivities available in the higher harmonics. The computer supported and heuristic methods were compared. Their advantages and limitations are discussed.
Unexpected Complexity in the Electro-Oxidation of Iodide on Gold in the Ionic Liquid 1-Ethyl-3-rnethylimidazolium bis(trifluoromethanesulfonyl)imide
Publisher: American Chemical Society (ACS)
Date: 15-11-2013
DOI: 10.1021/AC402150Y
Electron transfer reactions at gold nanoparticles
Publisher: Royal Society of Chemistry (RSC)
Date: 2001
DOI: 10.1039/B103458H
Abstract: It is demonstrated that scanning electrochemical microscopy can be used to investigate the kinetics of electron transfer reactions catalysed by metal nanoparticles supported on an insulating substrate.
Polyaniline Langmuir–Blodgett films: formation and properties
Publisher: Royal Society of Chemistry (RSC)
Date: 2009
DOI: 10.1039/B819809H
Abstract: The deposition and characterisation of Langmuir-Blodgett (LB) layers of polyaniline (PAN) on solid supports is described. Langmuir films were spread as a mixture of PAN and dodecylbenzenesulfonic acid (DBSA) at the water/air interface and deposited on either glass or indium tin oxide (ITO). Mono- and multi-layer films of PAN/DBSA were characterized by X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), absorption spectroscopy and cyclic voltammetry (CV). The ultrathin films produced were found to be highly uniform and very stable. Further characterisation of the films was accomplished by scanning electrochemical microscopy (SECM) in the feedback mode. It was found that the conductivity depended strongly on the pH of the solution and the number of layers deposited. Values for the pH-dependent lateral conductivity of PAN LB films are reported.
Mechanistic analysis of the electrocatalytic properties of dissolved alpha and beta isomers of SiW12O40 (4-) and solid Ru(bipy)(3) (2) alpha-SiW12O40 on the reduction of nitrite in acidic aqueous media
Publisher: American Chemical Society (ACS)
Date: 04-2006
DOI: 10.1021/IC0519943
Abstract: Voltammetric studies on the reduction of alpha and beta isomers of the Keggin polyoxometalate anion [SiW12O40]4- reveal a series of electrochemically reversible processes in acidic aqueous media. In the presence of NO2-, catalytic current is detected in the potential region of the [SiW12O40]4-/5- process. Electronic spectroscopy and simulation of voltammetric data undertaken at variable [NO2-] and [H+] allow the following mechanism to be postulated, [SiW12O40]4- + e- [SiW12O40]5-, H+ + HNO2 NO+ + H2O, NO+ + [SiW12O40]5- --> NO + [SiW12O40]4-. The second-order rate constant for the rate-determining step is faster for the alpha isomer than for the beta one. This may be attributed to the different reversible potentials of -0.144 V (alpha isomer) and -0.036 V vs Ag/AgCl (beta isomer) and, hence, smaller driving force for an assumed outer sphere electron-transfer reaction in the case of beta isomer. A stable, water-insoluble, thin-film [Ru(bipy)3]2[alpha-SiW12O40] chemically modified electrode was generated electrochemically via ion-exchange of [Ru(bipy)3]2+ with Bu4N+ in the [Bu4N]4[alpha-SiW12O40] solid. The first reduction process with this modified electrode gives rise to the reaction [Ru(bipy)3]2[alpha-SiW12O40](solid) + H+(soln) + e- H[Ru(bipy)3]2[alpha-SiW12O40](solid). The need to transfer a proton from the solution to the solid phase for charge neutralization purposes introduces a hydrogen-ion concentration dependence into this reaction, which is not found in the solution-phase study. Nevertheless, the voltammetric catalytic activity with respect to nitrite reduction is retained with the chemically modified electrode. However, nitrite catalysis with the [Ru(bipy)3]2[alpha-SiW12O40]-modified electrode is now independent of concentration of H+, rather than exhibiting a first-order dependence, and full mechanistic details for this process are unknown.
Recent advances in the nanoengineering of electrocatalysts for CO2reduction
Publisher: Royal Society of Chemistry (RSC)
Date: 2018
DOI: 10.1039/C7NR09620H
Abstract: Go nano, go active: the performance of catalysts for electrocatalytic CO 2 reduction can be improved by a range of nanoengineering strategies. Through these strategies, the catalyst's morphology, electronic structures and surrounding environment are finely tuned on a nanoscale.
Effect of Fatty Alcohol Monolayers on the Rate of Bromine Transfer across the Water/Air Interface: Assessment of Candidate Models Using Scanning Electrochemical Microscopy
Publisher: American Chemical Society (ACS)
Date: 18-01-2002
DOI: 10.1021/LA011051S
Electrochemistry of nickel(II) and copper(II) N,N'-ethylenebis(acetylacetoniminato) complexes and their electrocatalytic activity for reduction of carbon dioxide and carboxylic acid protons
Publisher: Springer Science and Business Media LLC
Date: 02-08-2014
CdS-Enhanced Ethanol Selectivity in Electrocatalytic CO2 Reduction at Sulfide-Derived Cu−Cd
Publisher: Wiley
Date: 16-06-2021
Abstract: The development of Cu‐based catalysts for the electrochemical CO 2 reduction reaction (eCO 2 RR) is of major interest for generating commercially important C 2 liquid products such as ethanol. Cu is exclusive among the eCO 2 RR metallic catalysts in that it facilitates the formation of a range of highly reduced C 2 products, with a reasonable total faradaic efficiency but poor product selectivity. Here, a series of new sulfide‐derived copper‐cadmium catalysts (SD‐Cu x Cd y ) was developed. An excellent faradaic efficiency of around 32 % but with a relatively low current density of 0.6 mA cm −2 for ethanol was obtained using the SD‐CuCd 2 catalyst at the relatively low overpotential of 0.89 V in a CO 2 ‐saturated aqueous 0.10 m KHCO 3 solution with an H‐cell. The current density increased by an order of magnitude under similar conditions using a flow cell where the mass transport rate for CO 2 was greatly enhanced. Ex situ spectroscopic and microscopic, and voltammetric investigations pointed to the role of abundant phase boundaries between CdS and Cu + /Cu sites in the SD‐CuCd 2 catalyst in enhancing the selectivity and efficiency of ethanol formation at low potentials.
Pt nanoparticle label-mediated deposition of Pt catalyst for ultrasensitive electrochemical immunosensors
Publisher: Elsevier BV
Date: 10-2010
DOI: 10.1016/J.BIOS.2010.07.112
Abstract: Herein we describe a novel signal lification strategy for the development of ultrasensitive electrochemical immunosensors. The lification strategy is based on platinum catalyzing a hydrogen evolution reaction. To demonstrate its practicality, the electrochemical signal enhancement strategy has been applied for the development of a novel prostate-specific antigen (PSA) immunosensor. The immunosensing protocol utilized a gold electrode with PSA capture antibodies bound to its surface via covalent bonding. After PSA was bound to the electrode surface, a secondary platinum nanoparticle-labeled detection antibody was used to complete the sandwich immunosensor. The resulting electrode was then dipped in a platinum developer solution containing 1 mM of PtCl4(2-), 0.1M of formate (reductant) and 0.5% Tween 80 (pH 6.5) to generate bare platinum catalysts in close proximity to the Au electrode surface through a seed-mediated nucleation and growth mechanism. The signal readout was obtained electrochemically via a Pt-catalyzed hydrogen evolution reaction in an acidic aqueous medium containing 10 mM of HCl and 1 M of KCl. A detection limit of 1 fg/ml was achieved.
Separation of electron-transfer and coupled chemical reaction components of biocatalytic processes using Fourier transform ac voltammetry
Publisher: American Chemical Society (ACS)
Date: 23-04-2005
DOI: 10.1021/AC048151Y
Abstract: The underlying electron-transfer and coupled chemical processes associated with biologically important catalytic reactions can be resolved using a combination of Fourier transform ac voltammetry with an analysis of the separated dc and ac components. This outcome can be achieved because the response associated with generation of the catalytic current is essentially confined to the steady-state dc component, whereas the electron-transfer step is dominant in the fundamental and higher harmonics. For the mediated oxidation of glucose with glucose oxidase, it was found that the underlying reversible redox chemistry of the mediator, ferrocenemonocarboxylic acid, as detected in the third and higher harmonics, was totally unaffected by introduction of the catalytic process. In contrast, for the catalytic reduction of molecular oxygen by cytochrome P450, slight changes in the P450 redox process were detected when the catalytic reaction was present. Simulations of a simple catalytic reaction scheme support the fidelity of this novel FT ac voltammetric approach for examining mechanistic nuances of catalytic forms of electrochemical reaction schemes.
Dual Quantum Dot‐Decorated Bismuth Vanadate Photoanodes for Highly Efficient Solar Water Oxidation
Publisher: Wiley
Date: 18-02-2019
Abstract: Photo-induced charge separation and photon absorption play important roles in determining the performance of the photoelectrocatalytic water splitting process. In this work, we utilize dual quantum dots (QDs), consisting of BiVO
Electrochemical Proton Reduction and Equilibrium Acidity (pKa) in Aprotic Ionic Liquids: Protonated Amines and Sulfonamide Acids
Publisher: American Chemical Society (ACS)
Date: 16-09-2015
Higher Harmonic Large-Amplitude Fourier Transformed Alternating Current Voltammetry: Analytical Attributes Derived from Studies of the Oxidation of Ferrocenemethanol and Uric Acid at a Glassy Carbon E
Publisher: American Chemical Society (ACS)
Date: 17-05-2008
DOI: 10.1021/AC0715221
Abstract: An analytical evaluation of the higher ac harmonic components derived from large litude Fourier transformed voltammetry is provided for the reversible oxidation of ferrocenemethanol (FcMeOH) and oxidation of uric acid by an EEC mechanism in a pH 7.4 phosphate buffer at a glassy carbon (GC) electrode. The small background current in the analytically optimal fifth harmonic is predominantly attributed to faradaic current associated with the presence of electroactive functional groups on the GC electrode surface, rather than to capacitive current which dominates the background in the dc, and the initial three ac harmonics. The detection limits for the dc and the first to fifth harmonic ac components are 1.9, 5.89, 2.1, 2.5, 0.8, and 0.5 microM for FcMeOH, respectively, using a sine wave modulation of 100 mV at 21.46 Hz and a dc sweep rate of 111.76 mV s (-1). Analytical performance then progressively deteriorates in the sixth and higher harmonics. For the determination of uric acid, the capacitive background current was enhanced and the reproducibility lowered by the presence of surface active uric acid, but the rapid overall 2e (-) rather than 1e (-) electron transfer process gives rise to a significantly enhanced fifth harmonic faradaic current which enabled a detection limit of 0.3 microM to be achieved which is similar to that reported using chemically modified electrodes. Resolution of overlapping voltammetric signals for a mixture of uric acid and dopamine is also achieved using higher fourth or fifth harmonic components, under very low background current conditions. The use of higher fourth and fifth harmonics exhibiting highly favorable faradaic to background (noise) current ratios should therefore be considered in analytical applications under circumstances where the electron transfer rate is fast.
Investigation of Mediated Oxidation of Ascorbic Acid by Ferrocenemethanol Using Large-Amplitude Fourier Transformed ac Voltammetry under Quasi-Reversible Electron-Transfer Conditions at an Indium Tin
Publisher: American Chemical Society (ACS)
Date: 31-07-2008
DOI: 10.1021/AC702531F
Abstract: The ability of the technique of large- litude Fourier transformed (FT) ac voltammetry to facilitate the quantitative evaluation of electrode processes involving electron transfer and catalytically coupled chemical reactions has been evaluated. Predictions derived on the basis of detailed simulations imply that the rate of electron transfer is crucial, as confirmed by studies on the ferrocenemethanol (FcMeOH)-mediated electrocatalytic oxidation of ascorbic acid. Thus, at glassy carbon, gold, and boron-doped diamond electrodes, the introduction of the coupled electrocatalytic reaction, while producing significantly enhanced dc currents, does not affect the ac harmonics. This outcome is as expected if the FcMeOH (0/+) process remains fully reversible in the presence of ascorbic acid. In contrast, the ac harmonic components available from FT-ac voltammetry are predicted to be highly sensitive to the homogeneous kinetics when an electrocatalytic reaction is coupled to a quasi-reversible electron-transfer process. The required quasi-reversible scenario is available at an indium tin oxide electrode. Consequently, reversible potential, heterogeneous charge-transfer rate constant, and charge-transfer coefficient values of 0.19 V vs Ag/AgCl, 0.006 cm s (-1) and 0.55, respectively, along with a second-order homogeneous chemical rate constant of 2500 M (-1) s (-1) for the rate-determining step in the catalytic reaction were determined by comparison of simulated responses and experimental voltammograms derived from the dc and first to fourth ac harmonic components generated at an indium tin oxide electrode. The theoretical concepts derived for large- litude FT ac voltammetry are believed to be applicable to a wide range of important solution-based mediated electrocatalytic reactions.
Electrochemical Proton Reduction and Equilibrium Acidity (pKa) in Aprotic Ionic Liquids: Phenols, Carboxylic Acids, and Sulfonic Acids
Publisher: American Chemical Society (ACS)
Date: 16-09-2015
Metal-Templated Macrocycle Synthesis in an Ionic Liquid: A Comparison With Reaction in Protic Solvents
Publisher: Informa UK Limited
Date: 03-12-2012
Electroless deposition of iridium oxide nanoparticles promoted by condensation of [Ir(OH)6]2−on an anodized Au surface: application to electrocatalysis of the oxygen evolution re
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C4RA14392B
Abstract: High reactivity of anodized gold allows electroless deposition of active IrO x nanoparticles. With its highly stable electrocatalytic activity for OER, the method is the simplest yet developed.
Predicting 17O NMR chemical shifts of polyoxometalates using density functional theory
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C5CP07766D
Abstract: We have investigated the computation of 17 O NMR chemical shifts of a wide range of polyoxometalates using density functional theory.
Separating the Effects of Experimental Noise from Inherent System Variability in Voltammetry: The [Fe(CN)_6]^3−/4− Process
Publisher: American Chemical Society (ACS)
Date: 10-2018
DOI: 10.26434/CHEMRXIV.7149281.V1
Abstract: Recently, we have introduced the use of techniques drawn from Bayesian statistics to recover kinetic and thermodynamic parameters from voltammetric data, and were able to show that the technique of large litude ac voltammetry yielded significantly more accurate parameter values than the equivalent dc approach. In this paper we build on this work to show that this approach allows us, for the first time, to separate the effects of random experimental noise and inherent system variability in voltammetricexperiments. We analyse ten repeated experimental data sets for the [Fe(CN) 6 ] 3−/4− process, again using large- litude ac cyclic voltammetry. In each of the ten caseswe are able to obtain an extremely good fit to the experimental data and obtain very narrow distributions of the recovered parameters governing both the faradaic (the reversible formal faradaic potential, E_0, the standard heterogeneous charge transfer rate constant k_0, and the charge transfer coefficient α) and non-faradaic terms (uncompensated resistance, R_u , and double layer capacitance, C_dl). We then employ hierarchicalBayesian methods to recover the underlying “hyperdistribution” of the faradaic and non-faradaic parameters, showing that in general the variation between the experimental data sets is significantly greater than suggested by in idual experiments, except for α where the inter-experiment variation was relatively minor. Correlations between pairs of parameters are provided, and for ex le, reveal a weak link between k_0 and C_dl (surface activity of a glassy carbon electrode surface). Finally, we discuss theimplications of our findings for voltammetric experiments more generally.
Studies on monoxide emission spectrometry of rare-earth elements. IV. Simultaneous determination of Sm, Eu, Gd in SmEuGd concentrates by the dual wavelength method
Publisher: Elsevier BV
Date: 09-1997
Effect of Steroids on Coronavirus Disease 2019 (COVID-19) Mortality Risk: A Bayesian Interpretation
Publisher: Oxford University Press (OUP)
Date: 29-11-2021
DOI: 10.1093/CID/CIAA1783
Large amplitude Fourier transformed ac voltammetry at a rotating disc electrode: a versatile technique for covering Levich and flow rate insensitive regimes in a single experiment
Publisher: Royal Society of Chemistry (RSC)
Date: 2012
DOI: 10.1039/C2CP23819E
Abstract: The theory for large litude Fourier transformed ac voltammetry at a rotating disc electrode is described. Resolution of time domain data into dc and ac harmonic components reveals that the mass transport for the dc component is controlled by convective-diffusion, while the background free higher order harmonic components are flow rate insensitive and mainly governed by linear diffusion. Thus, remarkable versatility is available Levich behaviour of the dc component limiting current provides diffusion coefficient values and access to higher harmonics allows fast electrode kinetics to be probed. Two series of experiments (dc and ac voltammetry) have been required to extract these parameters here large litude ac voltammetry with RDE methodology is used to demonstrate that kinetics and diffusion coefficient information can be extracted from a single experiment. To demonstrate the power of this approach, theoretical and experimental comparisons of data obtained for the reversible [Ru(NH(3))(6)](3+/2+) and quasi-reversible [Fe(CN)(6)](3-/4-) electron transfer processes are presented over a wide range of electrode rotation rates and with different concentrations and electrode materials. Excellent agreement of experimental and simulated data is achieved, which allows parameters such as electron transfer rate, diffusion coefficient, uncompensated resistance and others to be determined using a strategically applied approach that takes into account the different levels of sensitivity of each parameter to the dc or the ac harmonic.
Automatically Identifying Electrode Reaction Mechanisms Using Deep Neural Networks
Publisher: American Chemical Society (ACS)
Date: 30-08-2019
DOI: 10.1021/ACS.ANALCHEM.9B01891
Abstract: At present, electrochemical mechanisms are most commonly identified subjectively based on the experience of the researcher. This subjectivity is reflected in bias to particular mechanisms as well as lack of quantifiable confidence in the chosen mechanism compared to potential alternative mechanisms. In this paper we demonstrate that a deep neural network trained to recognize dc cyclic voltammograms for three commonly encountered mechanisms provides correct classifications within 5 ms without the problem of subjectivity. To mimic experimental data, the impact of noise, uncompensated resistance, and dependence on scan rate, factors that are relevant to practical studies, has also been investigated. Outcomes with two experimental data sets are also presented.
Phosphomolybdic Acid‐Assisted Growth of Ultrathin Bismuth Nanosheets for Enhanced Electrocatalytic Reduction of CO2 to Formate
Publisher: Wiley
Date: 07-02-2019
Abstract: Oxides containing two-dimensional metallic catalysts have shown enhanced catalytic activity, stability, and product selectivity. Porous three-dimensional structures maximize the accessibility of the active sites, thus enhancing the catalytic performance of the catalysts. By integrating these desirable features in a single catalyst, further improvement in catalytic activity and selectivity is expected. In this study, oxide-containing bismuth (Bi) nanosheets of about 4 nm thickness interconnected to form a porous three-dimensional structure were synthesized by electrodeposition in the presence of phosphomolybdic acid under hydrogen evolution conditions. These Bi nanosheets catalyze CO
Architectural Design for Enhanced C2 Product Selectivity in Electrochemical CO2 Reduction Using Cu-Based Catalysts: A Review
Publisher: American Chemical Society (ACS)
Date: 06-05-2021
Probing Electrolyte Cation Effects on the Electron Transfer Kinetics of the [α-SiW 12 O 40 ] 4−/5− and [α-SiW 12 O 40 ] 5−/6− Processes using a Boron-Doped Diamond Electrode
Publisher: Elsevier BV
Date: 10-2015
Voltammetric Determination of the Reversible Potentials for [{Ru4O4(OH)2(H2O)4}(γ-SiW10O36)2]10– over
Publisher: American Chemical Society (ACS)
Date: 08-10-2013
DOI: 10.1021/IC401748Y
Abstract: Voltammetric studies of the Ru-containing polyoxometalate water oxidation molecular catalyst [{Ru4O4(OH)2(H2O)4}(γ-SiW10O36)2](10-) ([1(γ-SiW10O36)2](10-) where 1 represents the {Ru4O4(OH)2(H2O)4} core and 1(0) stands for its initial form with all ruthenium centers in the oxidation state IV) have been carried out in aqueous media over a wide range of pH (2-12 using Britton-Robinson buffer) and ionic strength. Well-defined voltammograms in buffered media are only obtained when Frumkin double layer effects are suppressed by the presence of a sufficient concentration of additional supporting electrolyte (LiNO3, NaNO3, KNO3, Ca(NO3)2, Mg(NO3)2, MgSO4, or Na2SO4). A combination of data derived from dc cyclic, rotating disk electrode, and Fourier transformed large litude ac voltammetry allow the assignment of two processes related to reduction of the framework and the complete series of Ru(III/IV) and Ru(IV/V) redox processes and also provide their reversible potentials. Analysis of these data reveals that K(+) has a significantly stronger interaction with 1(1) (the number inside bracket stands for the number of electrons removed from 1(0)) than found for the other cations investigated, and hence its presence significantly alters the pH dependence of the 1(0)/1(1) reversible potential. Comparison of experimental data with theory developed in terms of equilibrium constants for process 1(0)/1(1) reveals that both H(+) and K(+) interact competitively with both 1(0) and 1(1). Importantly, reversible potential data reveal that (i) proton transfer does not necessarily need to be coupled to all electron transfer steps to achieve catalytic oxidation of water, (ii) the four-electron oxidized form, 1(4), is capable of oxidizing water under all conditions studied, and (iii) under some conditions, the three-electron oxidized form, 1(3), also exhibits considerable catalytic activity.
Lindqvist Polyoxoniobate Ion-Assisted Electrodeposition of Cobalt and Nickel Water Oxidation Catalysts
Publisher: American Chemical Society (ACS)
Date: 27-07-2015
Abstract: A method has been developed for the efficient electrodeposition of cobalt and nickel nanostructures with the assistance of the Lindqvist ion [Nb6O19](8-). Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), Raman spectroscopy, inductively coupled plasma mass spectrometry (ICP-MS), inductively coupled plasma optical emission spectrometry, and a range of electrochemical techniques have been used to characterize the morphology, composition, catalytic water oxidation activity and stability of the films in alkaline solution. SEM images show that films consisting of nanoparticles with diameters of ca. 30 to 40 nm are formed after 40-50 potential cycles of deposition. Nb and Co/Ni are detected in the films by EDX. ICP-MS results show an elemental ratio of 1:1 for Co:Nb and 1:3 for Ni:Nb, respectively. Raman spectra reveal the presence of both [Nb6O19](8-) and Co(OH)2/Ni(OH)2. The films exhibit excellent stability and efficiency for electrocatalytic water oxidation in alkaline solution. Turnover frequencies of 12.9 and 13.2 s(-1) were determined by rotating ring disk electrode voltammetry at an overpotential of 480 mV for Co and Ni films, respectively. Fourier transformed large litude alternating current (FTAC) voltammetry reveals an additional underlying oxidation process for Co under catalytic turnover conditions, which indicates that a Co(IV) species is involved in the efficient catalytic water oxidation reactions. FTAC voltammetric data also suggest that the Ni films undergoes a clear phase transformation upon aging in aqueous 1 M NaOH and the electrogenerated higher oxidation state Ni from β-NiOOH is the more active form of the catalyst.
Opportunities and challenges in applying machine learning to voltammetric mechanistic studies
Publisher: Elsevier BV
Date: 08-2022
Mechanistic understanding of the electrocatalytic CO2 reduction reaction – New developments based on advanced instrumental techniques
Publisher: Elsevier BV
Date: 04-2020
Ultra‐thin Pd and CuPd Bimetallic Alloy Nanosheets for Electrochemical Reduction of CO2
Publisher: Wiley
Date: 02-2022
Abstract: Pd is an attractive electrocatalyst for the conversion of CO 2 to CO. Herein, we report the synthesis of ultrathin Pd nanosheets with a (111) exposed facet which enables CO evolution to be achieved in a CO 2 saturated 0.1 m KHCO 3 solution in a conventional H‐cell with a faradaic efficiency of 74±4 % at −0.75 V vs RHE and a partial current density (calculated based on the geometric area) of −0.65 mA cm −2 . Further, to reduce the cost, Cu was introduced into the Pd nanosheets to form Cu x Pd y bimetallic alloy nanosheets with (111) exposed planes. The composition of the Cu x Pd y alloy played a significant role in determining the nature of the nanosheet structure and the product selectivity. When 50 % of the Pd was replaced by Cu, competitive CO evolution could still be achieved relative to use of purely Pd nanosheets with 57±5 % of CO achieved at −0.85 V vs RHE and a partial current density of −0.9 mA cm −2 . Under flow‐cell conditions with a higher CO 2 mass transport rate, CuPd nanosheets exhibited enhanced current densities in the range of −5 mA cm −2 to −35 mA cm −2 but with a negligible change in faradaic efficiencies irrespective of the applied potential in a 1.0 m KHCO 3 medium. The use of a 1.0 m KOH solution further improved the catalytic performance generating 71±3 % of CO with a partial current density of −58±2 mA cm −2 at a low potential of −0.6 V vs RHE. Post electrolysis characterization revealed structural transformations occurred during electrolysis that impacted the product selectivity of some catalysts.
Modeling the Influence of Low Concentrations of Water on the Thermodynamics, Electron Transfer Kinetics, and Diffusivity of the [Ru(CN)6]4–/3– Process in Propylene Carbonate
Publisher: American Chemical Society (ACS)
Date: 18-05-2020
Selective electrochemical hydrogenation of furfural to 2-methylfuran over a single atom Cu catalyst under mild pH conditions
Publisher: Royal Society of Chemistry (RSC)
Date: 2021
DOI: 10.1039/D0GC03999C
Abstract: Furfural can be electrochemically hydrogenated to 2-methylfuran in mild conditions with high selectivity using a catalyst containing single atom copper active sites and oxophilic phosphorus dopants.
Theoretical Evaluation of Possible 2D Boron Monolayer in N2 Electrochemical Conversion into Ammonia
Publisher: American Chemical Society (ACS)
Date: 22-10-2018
Applications of voltammetric ion selective electrodes to complex matrices
Publisher: Royal Society of Chemistry (RSC)
Date: 2013
DOI: 10.1039/C3AY40769A
Large-Amplitude Fourier Transformed High-Harmonic Alternating Current Cyclic Voltammetry: Kinetic Discrimination of Interfering Faradaic Processes at Glassy Carbon and at Boron-Doped Diamond Electrod
Publisher: American Chemical Society (ACS)
Date: 15-05-2004
DOI: 10.1021/AC049744B
Abstract: Significant advantages of Fourier transformed large- litude ac higher (second to eighth) harmonics relative to responses obtained with conventional small- litude ac or dc cyclic voltammetric methods have been demonstrated with respect to (i) the suppression of capacitive background currents, (ii) the separation of the reversible reduction of [Ru(NH(3))(6)](3+) from the overlapping irreversible oxygen reduction process under conditions where aerobic oxygen remains present in the electrochemical cell, and (iii) the kinetic resolution of the reversible [Ru(NH(3))(6)](3+/2+) process in mixtures of [Fe(CN)(6)](3-) and [Ru(NH(3))(6)](3+) at appropriately treated boron-doped diamond electrodes, even when highly unfavorable [Fe(CN)(6)](3-) to [Ru(NH(3))(6)](3+) concentration ratios are employed. Theoretical support for the basis of kinetic discrimination in large- litude higher harmonic ac cyclic voltammetry is provided.
Electrochemical maps and movies of the hydrogen evolution reaction on natural crystals of molybdenite (MoS2): basal vs. edge plane activity
Publisher: Royal Society of Chemistry (RSC)
Date: 2017
DOI: 10.1039/C7SC02545A
Abstract: In this work, we report the first spatially-resolved voltammetric measurements of the hydrogen evolution reaction on natural crystals of molybdenite, unequivocally demonstrating enhanced catalytic activity on the edge plane relative to the basal plane.
Synergistic Functionalization for Promoting Dinitrogen Electroreduction with High Faradaic Efficiency
Publisher: Elsevier BV
Date: 2021
DOI: 10.2139/SSRN.3779558
Investigation of the Kinetics and Mechanism of Acid Chloride Hydrolysis in an Oil/Water System Using Microelectrochemical Measurements at Expanding Droplets (MEMED)
Publisher: American Chemical Society (ACS)
Date: 27-01-2004
DOI: 10.1021/LA0355951
Epidemiological transition to mortality and refracture following an initial fracture
Publisher: eLife Sciences Publications, Ltd
Date: 09-02-2021
DOI: 10.7554/ELIFE.61142
Abstract: This study sought to redefine the concept of fracture risk that includes refracture and mortality, and to transform the risk into "skeletal age". We analysed data obtained from 3521 women and men aged 60 years and older, whose fracture incidence, mortality, and bone mineral density (BMD) have been monitored since 1989. During the 20-year follow-up period, among 632 women and 184 men with a first incident fracture, the risk of sustaining a second fracture was higher in women (36%) than in men (22%), but mortality risk was higher in men (41%) than in women (25%). The increased risk of mortality was not only present with an initial fracture, but was accelerated with refractures. Key predictors of post-fracture mortality were male gender (hazard ratio [HR] 2.4 95% CI, 1.79–3.21), advancing age (HR 1.67 1.53–1.83), and lower femoral neck BMD (HR 1.16 1.01–1.33). A 70-year-old man with a fracture is predicted to have a skeletal age of 75. These results were incorporated into a prediction model to aid patient-doctor discussion about fracture vulnerability and treatment decisions.
Scanning electrochemical microscopy (SECM) feedback approach for measuring lateral proton diffusion in langmuir monolayers: theory and application
Publisher: Royal Society of Chemistry (RSC)
Date: 04-07-2002
DOI: 10.1039/B111399B
Misclassification and measurement error – planning a study and interpreting results
Publisher: RCN Publishing Ltd.
Date: 11-03-2021
Modular Molecules: Site-Selective Metal Substitution, Photoreduction, and Chirality in Polyoxometalate Hybrids
Publisher: Wiley
Date: 09-09-2014
Abstract: The first members of a promising new family of hybrid amino acid-polyoxometalates have emerged from a search for modular functional molecules. Incorporation of glycine (Gly) or norleucine (Nle) ligands into an yttrium-tungstoarsenate structural backbone, followed by crystallization with p-methylbenzylammonium (p-MeBzNH3(+)) cations, affords (p-MeBzNH3)6K2(GlyH)[As(III)4(Y(III)W(VI)3)W(VI)44Y(III)4O159(Gly)8(H2O)14]⋅47 H2O (1) and enantiomorphs (p-MeBzNH3)15(NleH)3[As(III)4(Mo(V)2Mo(VI)2)W(VI)44Y(III)4O160(Nle)9(H2O)11][As(III)4(Mo(VI)2W(VI)2)W(VI)44Y(III)4O160(Nle)9(H2O)11] (generically designated 2: L-Nle, 2 a D-Nle, 2 b). An intensive structural, spectroscopic, electrochemical, magnetochemical and theoretical investigation has allowed the elucidation of site-selective metal substitution and photoreduction of the tetranuclear core of the hybrid polyanions. In the solid state, markedly different crystal packing is evident for the compounds, which indicates the role of noncovalent interactions involving the amino acid ligands. In solution, mass spectrometric and small-angle X-ray scattering studies confirm maintenance of the structure of the polyanions of 2, while circular dichroism demonstrates that the chirality is also maintained. The combination of all of these features in a single modular family emphasizes the potential of such hybrid polyoxometalates to provide nanoscale molecular materials with tunable properties.
New Approach for Measuring Lateral Diffusion in Langmuir Monolayers by Scanning Electrochemical Microscopy (SECM): Theory and Application
Publisher: American Chemical Society (ACS)
Date: 20-10-2001
DOI: 10.1021/JP004592J
Unlocking the Electrocatalytic Activity of Antimony for CO2 Reduction by Two‐Dimensional Engineering of the Bulk Material
Publisher: Wiley
Date: 17-10-2017
Abstract: Two-dimensional (2D) materials are known to be useful in catalysis. Engineering 3D bulk materials into the 2D form can enhance the exposure of the active edge sites, which are believed to be the origin of the high catalytic activity. Reported herein is the production of 2D "few-layer" antimony (Sb) nanosheets by cathodic exfoliation. Application of this 2D engineering method turns Sb, an inactive material for CO
Fourier transformed alternating current voltammetry in electromaterials research: Direct visualisation of important underlying electron transfer processes
Publisher: Elsevier BV
Date: 08-2018
Evaluating Apps for Learning and Teaching
Publisher: International Association of Online Engineering (IAOE)
Date: 29-02-2012
Abstract: A growing number of educators and students are adopting mobile devices and using applications (apps). There are often no formal guidelines to assist with evaluating apps. A review of the literature was conducted to determine relevant criteria that could be applied to evaluating apps. Relevant ex les are included where appropriate. Evaluation criteria are offered to assist educators and students with determining the suitability of apps.
Study of the reaction of Rh(acac)(CO)2 with alkenes in polyethylene films under high-pressure hydrogen and the Rh-catalysed hydrogenation of alkenes
Publisher: Elsevier BV
Date: 07-2003
Polyoxometalate-Promoted Electrocatalytic CO2 Reduction at Nanostructured Silver in Dimethylformamide
Publisher: American Chemical Society (ACS)
Date: 27-03-2018
Abstract: Electrochemical reduction of CO
Models and Their Limitations in the Voltammmetric Parameterization of the Six‐Electron Surface‐Confined Reduction of [PMo12O40]3− at Glassy Carbon and Boron‐Doped Diam
Publisher: Wiley
Date: 31-10-2019
Electrode Material Dependence of the Electron Transfer Kinetics Associated with the [SVW11O40]3−/4− (VV/IV) and [SVW11O40]4−/5− (WVI/V) Processes in Dimethylformamide
Publisher: Elsevier BV
Date: 05-2016
Influence of 1-butyl-3-methylimidazolium on the electron transfer kinetics associated with the [SVW 11 O 40 ] 3−/4− (V V/IV ) and [SVW 11 O 40 ] 4−/5− (W VI/V ) processes in dimethylformamide
Publisher: Elsevier BV
Date: 10-2016
Phosphomolybdate-doped-poly(3,4-ethylenedioxythiophene) coated gold nanoparticles: Synthesis, characterization and electrocatalytic reduction of bromate
Publisher: Elsevier BV
Date: 11-2013
DOI: 10.1016/J.ACA.2013.04.036
Abstract: Phosphomolybdate, H3PMo12O40, (PMo12)-doped-poly(3,4-ethylenedioxythiophene) (PEDOT) coated gold nanoparticles have been synthesized in aqueous solution by reduction of AuCl4(-) using hydroxymethyl EDOT as a reducing agent in the presence of polystyrene sulfonate and PMo12. The resulting PMo12-doped-PEDOT stabilized Au nanoparticles are water soluble and have been characterized by UV-visible spectroscopy, scanning electron microscopy and electrochemistry. Glassy carbon electrodes modified with these Au nanoparticles show excellent stability and catalytic activity towards the reduction of bromate in an aqueous electrolyte solution containing 10mM H2SO4 and 0.1M Na2SO4.
Graphene-supported [{Ru4O4(OH)2(H2O)4}(γ-SiW10O36)2]10− for highly efficient electrocatalytic water oxidation
Publisher: Royal Society of Chemistry (RSC)
Date: 2013
DOI: 10.1039/C3EE41892H
Ultrasensitive Electrochemical DNA Biosensors Based on the Detection of a Highly Characteristic Solid‐State Process
Publisher: Wiley
Date: 08-06-2009
Cobalt selenide nanoflake decorated reduced graphene oxide nanocomposite for efficient glucose electro-oxidation in alkaline medium
Publisher: Royal Society of Chemistry (RSC)
Date: 2017
DOI: 10.1039/C7TA04742H
Abstract: A simple one pot hydrothermal procedure for the synthesis of cobalt selenide (CoSe) decorated reduced graphene oxide (rGO) is reported along with the application of this hybrid material as a new electrocatalyst for glucose oxidation.
Concentration and electrode material dependence of the voltammetric response of iodide on platinum, glassy carbon and boron-doped diamond in the room temperature ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide
Publisher: Elsevier BV
Date: 10-2013
Voltammetric studies in wet 1-butyl-1-methylpyrrolidinium bis (trifluoromethylsulfonyl)imide ionic liquid using electrodes with adhered microparticles
Publisher: Elsevier BV
Date: 03-2012
A chemist's guide to photoelectrode development for water splitting – the importance of molecular precursor design
Publisher: Royal Society of Chemistry (RSC)
Date: 2023
DOI: 10.1039/D3EY00176H
Mediator Enhanced Water Oxidation Using Rb4[RuII(bpy)3]5[{RuIII4O4(OH)2(H2O)4}(γ-SiW1
Publisher: American Chemical Society (ACS)
Date: 07-07-2014
DOI: 10.1021/IC500878W
Abstract: The water insoluble complex Rb4[Ru(II)(bpy)3]5[{Ru(III)4O4(OH)2(H2O)4}(γ-SiW10O36)2], ([Ru(II)bpy]5[Ru(III)4POM]), was synthesized from Rb8K2[{Ru(IV)4O4(OH)2(H2O)4}(γ-SiW10O36)2] and used for electrocatalytic water oxidation under both thin- and thick-film electrode conditions. Results demonstrate that the [Ru(II)bpy]5[Ru(III)4POM] modified electrode enables efficient water oxidation to be achieved at neutral pH using thin-film conditions, with [Ru(bpy)3](3+)([Ru(III)bpy]) acting as the electron transfer mediator and [Ru(V)4POM] as the species releasing O2. The rotating ring disc electrode (RRDE) method was used to quantitatively determine the turnover frequency (TOF) of the catalyst, and a value of 0.35 s(-1) was obtained at a low overpotential of 0.49 V (1.10 V vs Ag/AgCl) at pH 7.0. The postulated mechanism for the mediator enhanced catalytic water process in a pH 7 buffer containing 0.1 M LiClO4 as an additional electrolyte includes the following reactions (ion transfer for maintaining charge neutrality is omitted for simplicity): [Ru(II)bpy]5[Ru(III)4POM] → [Ru(III)bpy]5[Ru(V)4POM] + 13 e(-) and [Ru(III)bpy]5[Ru(V)4POM] + 2H2O → [Ru(III)bpy]5[Ru(IV)4POM] + O2 + 4H(+). The voltammetry of related water insoluble [Ru(II)bpy]2[S2M18O62] (M = W and Mo) and [Fe(II)Phen]x[Ru(III)4POM] materials has also been studied, and the lack of electrocatalytic water oxidation in these cases supports the hypothesis that [Ru(III)bpy] is the electron transfer mediator and [Ru(V)4POM] is the species responsible for oxygen evolution.
Investigation of Molecular Transfer Processes across Phospholipid Monolayers by the Combined Scanning Electrochemical Microscopy-Langmuir Trough Technique
Publisher: SAGE Publications
Date: 11-2007
Abstract: Scanning electrochemical microscopy (SECM) has emerged as a powerful techniquefor inducing and monitoring molecular transfer processes across water/air and liquid/liquid interfaces. At the same time, the Langmuir trough technique is a well established method for controlling the lateral pressure of molecular films of hiphilic molecules at interfaces. A combination of both methods allows the investigation of the permeability of monolayers in a defined state. A brief introduction of the SECM technique and the experimental set-up is presented. The application of the combined SECM- Langmuir trough technique to measure passive diffusion of small molecules (O2 and Br2) across phospholipid monolayers is then reviewed. Phospholipid monolayers at liquid/liquid and liquid/air interfaces serve as simple biomimetic models for biomembranes and the results of the combined SECM- Langmuir trough measurements have implications for understanding passive diffusion across cellular membranes.
Alloying strategies for tuning product selectivity during electrochemical CO2 reduction over Cu
Publisher: Royal Society of Chemistry (RSC)
Date: 2022
DOI: 10.1039/D2NR03539A
Abstract: Alloying is efficient for tuning product selectivity of copper in electrochemical reduction of CO 2 . Different alloying strategies and their impacts on product formation paths, the key challenges and future directions of the field have been reviewed.
Synthesis and characterization of diiron dithiolate complexes containing a quinoxaline bridge
Publisher: Royal Society of Chemistry (RSC)
Date: 2011
DOI: 10.1039/C1DT10953G
Abstract: A potential model complex for the hydrogenase active site, [Fe(2){(μ-CH(2)S)(2)R}(CO)(6)] (1) (R = quinoxaline), was synthesized by condensation of [(μ-LiS)(2)Fe(2)(CO)(6)] with 2,3-bis(bromomethyl)quinoxaline. Reactions of 1 with bis(diphenylphosphino)methane (dppm) under a range of conditions yielded substituted complexes [Fe(2){(μ-CH(2)S)(2)R}(CO)(5)(dppm)] (2), [Fe(2){(μ-CH(2)S)(2)R}(CO)(4)(k(2)-dppm)] (3) and [Fe(2){(μ-CH(2)S)(2)R}(CO)(4)(μ-dppm)] (4). X-ray crystallography confirms that in 2, the dppm is terminally bonded to an iron atom via one phosphorus atom, whereas in 3, it acts as a chelating ligand to coordinate to an iron center in a dibasal-substituted manner. In 4, the dppm bridges the two iron atoms in a cis basal/basal fashion with one phosphorus bonded to each iron atom. Treatment of 1 with various tertiary phosphines at room temperature in acetonitrile (MeCN) generates a range of mono-substituted products [Fe(2){(μ-CH(2)S)(2)R}(CO)(5)L] (5, L = PEt(3) 6, PMe(3) 7, PPh(3) 8, Me(2)PPh). With Bu(t)NC, mono- and di-substituted [Fe(2){(μ-CH(2)S)(2)R}(CO)(5)(Bu(t)NC)] (9) and [Fe(2){(μ-CH(2)S)(2)R}(CO)(4)(Bu(t)NC)(2)] (10) complexes are generated. All the complexes were characterized by elemental analysis, IR, MS and NMR spectroscopy. IR and NMR spectroscopic studies suggest that addition of excess HBF(4)·OEt(2) acid to 1-4 led to the protonation of quinoxaline nitrogen atoms. In contrast, 5-10 were not stable in acidic media. Electrochemistry of 1-4 was investigated in the acetonitrile medium (0.1 M Bu(4)NPF(6)). The electrochemical instability of the reduced ligand, quinoxaline, and the reduced forms of these complexes revealed from the electrochemical studies suggests that they do not provide ideal models of the hydrogenase active site.
Multi-products (C1 and C2) Formation from Electrochemical Reduction of Carbon Dioxide Catalyzed by Oxide-Derived Coppers Prepared Using Varied Synthesis Conditions
Publisher: Springer Science and Business Media LLC
Date: 13-02-2023
Two‐Dimensional Electrocatalysts for Efficient Reduction of Carbon Dioxide
Publisher: Wiley
Date: 10-10-2020
Abstract: Two-dimensional (2D) materials are attractive catalysts for the electrochemical reduction of carbon dioxide reaction (eCO
Unlocking the Electrocatalytic Activity of Antimony for CO2 Reduction by Two‐Dimensional Engineering of the Bulk Material
Publisher: Wiley
Date: 17-10-2017
Room Temperature Electrodeposition of Metallic Magnesium from Ethylmagnesium Bromide in Tetrahydrofuran and Ionic Liquid Mixtures
Publisher: The Electrochemical Society
Date: 03-12-2015
DOI: 10.1149/2.0051604JES
CC Bond Formation via CH Activation and CN Bond Formation via Oxidative Amination Catalyzed by Palladium‐ Polyoxometalate Nanomaterials Using Dioxygen as the Terminal Oxidant
Publisher: Wiley
Date: 20-10-2011
A Systematic Study of the Mass Transport, Kinetic and Thermodynamic Properties of the Fe-III/II Process at Glassy Carbon and Boron-Doped Diamond Electrodes
Publisher: Elsevier BV
Date: 09-2017
Unique Layer-Doping-Induced Regulation of Charge Behavior in Metal-Free Carbon Nitride Photoanodes for Enhanced Performance
Publisher: Wiley
Date: 13-12-2020
Abstract: Photoinduced charge carrier behavior is critical in determining photoelectrocatalytic activity. In this study, a unique layer-doped metal-free polymeric carbon nitride (C
Polyethylenimine promoted electrocatalytic reduction of CO2to CO in aqueous medium by graphene-supported amorphous molybdenum sulphide
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C5EE02879E
Abstract: Amorphous molybdenum sulphide immobilized on polyethylenimine modified reduced graphene oxide can catalyse the electroreduction of CO 2 to CO or “syngas” in aqueous media with high efficiency.
Electrohydrogenation of Carbon Dioxide using a Ternary Pd/Cu2O–Cu Catalyst
Publisher: Wiley
Date: 03-09-2019
Abstract: A simple one-pot method has been developed to synthesize a palladium/cuprous oxide-copper (Pd/Cu
Selective laser sintering of TiO2 nanoparticle film on plastic conductive substrate for highly efficient flexible dye-sensitized solar cell application
Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C3TA14210H
Abstract: Fast and selective laser sintering is efficient for the treatment of TiO 2 nanoparticle film for flexible DSC applications.
pH-Dependent solution dynamics of a manganese(ii ) polyoxometalate, [Mn4(H2O)2(P2W15O56)2]16−, and [Mn
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C5DT03138A
Abstract: The NMR-determined pH-dependent water–ligand exchange rate of a Mn( ii )-polyoxometalate varies by more than an order of magnitude, in contrast with those of a hexa-aqua ion.
Is the Imidazolium Cation a Unique Promoter for Electrocatalytic Reduction of Carbon Dioxide?
Publisher: American Chemical Society (ACS)
Date: 13-10-2016
Two Cobalt(II) 5-Aminoisophthalate Complexes and Their Stable Supramolecular Microporous Frameworks
Publisher: American Chemical Society (ACS)
Date: 11-07-2006
DOI: 10.1021/IC0602244
Abstract: Two stable supramolecular microporous cobalt(II) polymers, namely [Co(HAIP)2]n.3nH2O (1) and [Co(AIP)(H2O)]n (2), AIP = 5-aminoisophthalate, were hydrothermally synthesized and characterized by single-crystal X-ray diffraction, IR spectra, thermogravimetric analyses, and variable-temperature magnetic susceptibility measurements. The two complexes are constructed from the same Co2(CO2)2 SBU, which is extended into a 1D chain in 1 and a 2D layer in 2. As a result, 1 and 2 are 2D and 3D coordination polymers, respectively. The 3D supramolecular network of complex 1 is held up by strong hydrogen bonds formed between carboxylate groups and shows very high stability when the free H2O molecules are removed, indicating an extraordinarily stable H-bonding system. Upon water ligands being liberated, complex 2 becomes a stable microporous solid with coordination-unsaturated Co centers. The behavior of the susceptibility curve of 1 suggests the occurrence of an interesting intrachain antiferromagnetic coupling between the Co(II) ions and the presence of a significant orbital contribution, whereas the features of 2 indicate an antiferromagnetic coupling with T(N) = 3.5 K and a long-range antiferromagnetic order with a field-induced magnetic transition.
Fourier Transform Large-Amplitude Alternating Current Cyclic Voltammetry of Surface-Bound Azurin
Publisher: American Chemical Society (ACS)
Date: 25-11-2003
DOI: 10.1021/AC034901C
Production of hydrogen peroxide in commercial orange juice products is related to proximate composition, processing conditions and storage time
Publisher: Elsevier BV
Date: 11-2022
Voltammetric Perspectives on the Acidity Scale and H+/H2 Process in Ionic Liquid Media
Publisher: Annual Reviews
Date: 12-06-2018
DOI: 10.1146/ANNUREV-ANCHEM-061417-010022
Abstract: Nonhaloaluminate ionic liquids (ILs) have received considerable attention as alternatives to molecular solvents in erse applications spanning the fields of physical, chemical, and biological science. One important and often overlooked aspect of the implementation of these designer solvents is how the properties of the IL formulation affect (electro)chemical reactivity. This aspect is emphasized herein, where recent (voltammetric) studies on the energetics of proton (H + ) transfer and electrode reaction mechanisms of the H + /H 2 process in IL media are highlighted and discussed. The energetics of proton transfer, quantified using the p K a (minus logarithm of acidity equilibrium constant, K a ) formalism, is strongly governed by the constituent IL anion, and to a lesser extent, the IL cation. The H + /H 2 process, a model inner-sphere reaction, also displays electrochemical characteristics that are strongly IL-dependent. Overall, these studies highlight the need to carry out systematic investigations to resolve IL structure and function relationships in order to realize the potential of these erse and versatile solvents.
Voltammetric Studies on the Reduction of Polyoxometalate Anions in Ionic Liquids
Publisher: American Chemical Society (ACS)
Date: 14-06-2005
DOI: 10.1021/IC050032T
Abstract: The electrochemical reduction of tetrabutylammonium salts of isostructural pairs of polyoxometalates [Bu4N]2[M6O19], [Bu4N]4[alpha-SiM12O40], and [Bu4N]4[alpha-S2M18O62] (M = Mo or W) has been investigated at glassy carbon electrodes in dissolved and surface-confined states in ionic liquids and other media. In the ionic liquid 1-n-butyl-3-methylimidazolium hexafluorophosphate [BMIM][PF(6)], between two and six reversible one-electron-transfer processes were detected. Detailed studies on the process [alpha-S2W18O62](4-/5-) in a range of ionic liquids, water, and conventional organic solvents (containing 0.1 M electrolyte) suggest that the polarity of the medium plays a key role in the determination of the reversible potential. Reduction processes involving very highly charged [alpha-S2W18O62](8-/9-/10-) species are strongly influenced by the purity of the medium.
Electroanalytical Applications of Semiintegral and Convolution Voltammetry in Room-Temperature Ionic Liquids
Publisher: Springer International Publishing
Date: 2015
Resolution of coupled electron transfer–ion transfer processes at liquid/liquid interfaces by visualisation of interfacial concentration profiles
Publisher: Royal Society of Chemistry (RSC)
Date: 1999
DOI: 10.1039/A904641K
Radio frequency alternating electromagnetic field enhanced tetraruthenium polyoxometalate electrocatalytic water oxidation
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C8CC07642A
Abstract: RF-enhanced electrocatalytic water oxidation by protonated tetraruthenium polyoxometalate.
Unprecedented Formation of a Binuclear Au(II)–Au(II) Complex through Redox State Cycling: Electrochemical Interconversion of Au(I)–Au(I), Au(II)–Au(II), and Au(I)–Au(III) in Binuclear Complexes Contai
Publisher: American Chemical Society (ACS)
Date: 10-2019
DOI: 10.1021/ACS.INORGCHEM.9B01983
Abstract: The rational design of binuclear Au(I)-Au(I), Au(II)-Au(II), and Au(I)-Au(III) complexes requires an understanding of how the redox states interconvert. Herein, the electrochemical interconversion of the three oxidation states I, II, and III is reported on the voltammetric (cyclic and rotating disk electrode) time scales for binuclear gold complexes containing C
Voltammetric studies on decaphenylferrocene, substituted decaphenylferrocenes, and their oxidized forms in dichloromethane and ionic liquids
Publisher: American Chemical Society (ACS)
Date: 24-03-2005
DOI: 10.1021/OM049117C
Dietary patterns associated with obesity outcomes in adults: An umbrella review of systematic reviews
Publisher: Cambridge University Press (CUP)
Date: 22-02-2021
DOI: 10.1017/S1368980021000823
Abstract: The aim of this umbrella review was to summarise the evidence from existing systematic reviews on the association between different dietary patterns (DP) and overweight or obesity outcomes in adults. We followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and searched the MEDLINE, EMBASE, CINAHL, Cochrane, Scopus, and Web of Science for systematic reviews reporting on DP and weight gain or overweight/obesity outcomes. We identified 16 systematic reviews with 143 unique studies published between 2001 and 2019. Overall quality scores ranged from 4 to 10. Six reviews in 2/11 cohort and 6/19 cross-sectional studies reported (statistically significant) decreased OR for obesity (range: 0·53 to 0·73 and 0·35 to 0·88, respectively) associated with the Mediterranean diet. Five reviews in 5/15 cohort and 10/45 cross-sectional studies reported an inverse association between diet quality and weight gain or BMI ( β range: –1·3 to –0·09). Two reviews in 1/3 cohort and 1/2 cross-sectional studies reported a decreased risk of obesity (OR = 0·76) and weight gain (OR = 0·26), respectively, with fruit and vegetable intake. Five reviews of mixed DP in 3/40 cross-sectional studies reported an increased prevalence of obesity (OR = 1·19) or abdominal obesity (OR range: 1·07 to 1·27) with the Korean diet pattern. Our umbrella review confirms the hypothesis that Mediterranean-type DP reduce the risk of obesity in adults. Although population-specific evidence of effective interventions is needed, characteristics of Mediterranean-type DP are important considerations for national obesity prevention strategies.
Electrochemical Reduction of Carbon Dioxide in a Monoethanolamine Capture Medium
Publisher: Wiley
Date: 19-09-2017
Abstract: The electrocatalytic reduction of CO
Ultra-small Cu nanoparticles embedded in N-doped carbon arrays for electrocatalytic CO2 reduction reaction in dimethylformamide
Publisher: Springer Science and Business Media LLC
Date: 07-2018
Prognostic Implications of High-Sensitivity Troponin T Levels Among Patients Attending Emergency Departments and Evaluated for an Acute Coronary Syndrome
Publisher: Elsevier BV
Date: 08-2021
Electrochemical Reduction of CO2 at Metal Electrodes in a Distillable Ionic Liquid
Publisher: Wiley
Date: 10-05-2016
Abstract: The electroreduction of CO2 in the distillable ionic liquid dimethylammonium dimethylcarbamate (dimcarb) has been investigated with 17 metal electrodes. Analysis of the electrolysis products reveals that aluminum, bismuth, lead, copper, nickel, palladium, platinum, iron, molybdenum, titanium and zirconium electroreduce the available protons in dimcarb to hydrogen rather than reducing CO2 . Conversely, indium, tin, zinc, silver and gold are able to catalyze the reduction of CO2 to predominantly carbon monoxide (CO) and to a lesser extent, formate ([HCOO](-) ). In all cases, the applied potential was found to have a minimal influence on the distribution of the reduction products. Overall, indium was found to be the best electrocatalyst for CO2 reduction in dimcarb, with faradaic efficiencies of approximately 45 % and 40 % for the generation of CO and [HCOO](-) , respectively, at a potential of -1.34 V versus Cc(+/0) (Cc(+) =cobaltocenium) employing a dimethylamine to CO2 ratio of less than 1.8:1.
Electrochemistry of Iodide, Iodine, and Iodine Monochloride in Chloride Containing Nonhaloaluminate Ionic Liquids
Publisher: American Chemical Society (ACS)
Date: 15-01-2016
DOI: 10.1021/ACS.ANALCHEM.5B04332
Abstract: The electrochemical behavior of iodine remains a contemporary research interest due to the integral role of the I(-)/I3(-) couple in dye-sensitized solar cell technology. The neutral (I2) and positive (I(+)) oxidation states of iodine are known to be strongly electrophilic, and thus the I(-)/I2/I(+) redox processes are sensitive to the presence of nucleophilic chloride or bromide, which are both commonly present as impurities in nonhaloaluminate room temperature ionic liquids (ILs). In this study, the electrochemistry of I(-), I2, and ICl has been investigated by cyclic voltammetry at a platinum macrodisk electrode in a binary IL mixture composed of 1-butyl-3-methylimidazolium chloride ([C4mim]Cl) and 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([C2mim][NTf2]). In the absence of chloride (e.g., in neat [C2mim][NTf2]), I(-) is oxidized in an overall one electron per iodide ion process to I2 via an I3(-) intermediate, giving rise to two resolved I(-)/I3(-) and I3(-)/I2 processes, as per previous reports. In the presence of low concentrations of chloride ([Cl(-)] and [I(-)] are both <30 mM), an additional oxidation process appears at potentials less positive than the I3(-)/I2 process, which corresponds to the oxidation of I3(-) to the interhalide complex anion [ICl2](-), in an overall two electron per iodide ion process. In the presence of a large excess of Cl(-) ([I(-)] ≈ 10 mM and [Cl(-)] ≈ 3.7 M), I(-) is oxidized in an overall two electron per iodide ion process to [ICl2](-) via an [I2Cl](-) intermediate (confirmed by investigating the voltammetric response of ICl and I2 under these conditions). In summary, the I(-)/I2/I(+) processes in nonhaloaluminate ILs involve a complicated interplay between multiple electron transfer pathways and homogeneous chemical reactions which may not be at equilibrium on the voltammetric time scale.
A DNA biosensor based on the detection of doxorubicin-conjugated Ag nanoparticle labels using solid-state voltammetry
Publisher: Elsevier BV
Date: 10-2009
DOI: 10.1016/J.BIOS.2009.07.005
Abstract: This report describes an electrochemical biosensor for the detection of short DNA oligonucleotide of the avian flu virus H5N1 with sequence 5'-CCA AGC AAC AGA CTC AAA-3'. To fabricate this DNA biosensor, a gold (Au) electrode surface was modified with thiolated DNA probes with a sequence complementary to the target DNA. This modified Au electrode was incubated in a buffer solution containing the target DNA to form double-stranded DNA (ds-DNA) through hybridization. The ds-DNA on the electrode surface was then labeled with silver nanoparticles conjugated with a well-known DNA intercalator, doxorubicin. By performing cyclic voltammetry in an aqueous KCl solution (0.3M), the silver nanoparticle labels were detected as a result of the highly characteristic solid-state Ag/AgCl redox process. The signal obtained was subsequently used to quantify the amount of DNA. A detection limit of 1 pM has been achieved with this new DNA biosensor.
Lithium/bismuth co-functionalized phosphotungstic acid catalyst for promoting dinitrogen electroreduction with high Faradaic efficiency
Publisher: Elsevier BV
Date: 09-2021
Mixed-Metal Hybrid Polyoxometalates with Amino Acid Ligands: Electronic Versatility and Solution Properties
Publisher: American Chemical Society (ACS)
Date: 15-11-2016
DOI: 10.1021/ACS.INORGCHEM.6B02218
Abstract: Eight new members of a family of mixed-metal (Mo,W) polyoxometalates (POMs) with amino acid ligands have been synthesized and investigated in the solid state and solution using multiple physical techniques. While the peripheral POM structural framework is conserved, the different analogues vary in nuclearity of the central metal-oxo core, overall redox state, metal composition, and identity of the zwitterionic α-amino acid ligands. Structural investigations reveal site-selective substitution of Mo for W, with a strong preference for Mo to occupy the central metal-oxo core. This core structural unit is a closed tetrametallic loop in the blue reduced species and an open trimetallic loop in the colorless oxidized analogues. Density functional theory calculations suggest the core as the favored site of reduction and reveal that the corresponding molecular orbital is much lower in energy for a tetra- versus trimetallic core. The reduced species are diamagnetic, each with a pair of strongly antiferromagnetically coupled Mo
Advanced Composite 2D Energy Materials by Simultaneous Anodic and Cathodic Exfoliation
Publisher: Wiley
Date: 22-01-2018
Abstract: Composite materials based on graphene and other 2D materials are of considerable interest in the fields of catalysis, electronics, and energy conversion and storage because of the unique structural features and electronic properties of each component and the synergetic effects brought about by the compositing. Approaches to the mass production of 2D materials and their composites in a facile and affordable way are urgently needed to enable their implementation in practical applications. Here a novel electrochemical exfoliation approach to prepare 2D composites is proposed, which combines simultaneous anodic exfoliation of graphite and cathodic exfoliation of other 2D materials (namely MoS 2 , MnO 2 , and graphitic carbon nitride). The synthesis is carried out in a single‐compartment electrochemical cell to in situ produce functional 2D composite materials. Applications of the as‐prepared 2D composites are demonstrated as (i) effective hydrogen evolution catalysts and (ii) supercapacitor electrode materials. The method enables the compositing of semiconductive, or even insulating, 2D materials with conductive graphene in an easy, cheap, ecofriendly, yet efficient way, liberating the intrinsic functions of 2D materials, which are usually hindered by their poor conductivity. The method is believed to be widely applicable to the family of 2D materials.
A critical assessment of electrochemistry in a distillable room temperature ionic liquid, DIMCARB
Publisher: Royal Society of Chemistry (RSC)
Date: 2006
DOI: 10.1039/B512263E
Studies on monoxide flame emission spectrometry of rare-earth elements. Part 2. Determination of yttrium in rare-earth concentrates by the dual wavelength method
Publisher: Elsevier BV
Date: 06-1997
Bismuth Vanadate with Electrostatically Anchored 3D Carbon Nitride Nano‐networks as Efficient Photoanodes for Water Oxidation
Publisher: Wiley
Date: 16-07-2018
Abstract: In this study, we report a photoanode consisting of a polymeric/inorganic nanojunction between novel nanostructured 3D C
Voltammetric reduction of alpha- and gamma*- S2W18O62 (4-) and alpha-, beta-, and gamma- SiW12O40 (4-): Isomeric dependence of reversible potentials of polyoxometalate anions using data obtained by novel dissolution and conventional solution-phase processes
Publisher: American Chemical Society (ACS)
Date: 19-11-2004
DOI: 10.1021/IC049043X
Abstract: Comparative studies on the voltammetric reduction of the alpha and gamma isomers of Dawson [S(2)W(18)O(62)](4)(-) and alpha, beta, and gamma forms of Keggin [SiW(12)O(40)](4)(-) polyoxometalate anions have been undertaken. For the six reversible one-electron [S(2)W(18)O(62)](4)(-)(/5)(-)(/6)(-)(/7)(-)(/8)(-)(/9)(-)(/10)(-) processes in acetonitrile, reversible potentials (E(0)(')) were found to be independent of isomeric form within experimental error (+/-5 mV). However, because both the alpha and gamma* isomers of [Bu(4)N](4)[S(2)W(18)O(62)] are insoluble in water, solid-state voltammetric studies with microcrystals adhered to electrode surfaces in contact with aqueous Et(4)NCl and Bu(4)NCl electrolyte media were also possible. Although no isomeric distinction was again detected in the solid-state studies, it was found that reduction of adhered solid by four or more electron equivalents led to rapid dissolution. When Et(4)NCl was the electrolyte, this dissolution process coupled with potential cycling experiments enabled conventional solution-phase data to be obtained in water for the analogous six one-electron reduction steps previously detected in acetonitrile. A strong medium effect attributed to Lewis acidity effects was apparent upon comparison with E(0)(') data obtained in water and acetonitrile. In contrast, with the [SiW(12)O(40)](4)(-) system, E(0)(') values for the [SiW(12)O(40)](4)(-)(/5)(-)(/6)(-)(/7)(-) processes in acetonitrile exhibited a larger (about 70 mV) dependence on isomeric form, and the isomerization step, [gamma-SiW(12)O(40)](6)(-)--> [alpha-SiW(12)O(40)](6)(-), was detected on the voltammetric time scale. The influence of isomeric form on reversible potential data is considered in terms of structural and charge density differences exhibited in the [S(2)W(18)O(62)](4)(-) and [SiW(12)O(40)](4)(-) systems studied in this paper and published data available on the alpha, beta, gamma, and gamma isomers of [As(2)W(18)O(62)](6)(-) and [P(2)W(18)O(62)](6)(-) Dawson anions and Keggin systems.
AFM study of morphological changes associated with electrochemical solid-solid transformation of three-dimensional crystals of TCNQ to metal derivatives (metal∈=∈Cu, Co, Ni; TCNQ∈= ∈tetracyanoquinodimethane)
Publisher: Springer Science and Business Media LLC
Date: 27-09-2008
Changing the action of iron from stoichiometric to electrocatalytic in the hydrogenation of ketones in aqueous acidic media
Publisher: Wiley
Date: 18-09-2015
Abstract: Cyclohexanone, a model compound chosen to conveniently represent small oxygenates present in the aqueous phase of biomass hydrothermal upgrading streams, was hydrogenated in the presence of electrodeposited iron(0) using aqueous formic or sulfuric acid as a hydrogen donor. Under these conditions, zero-valent iron is consumed stoichiometrically and serves as both a formic acid decomposition site and a hydrogen transfer agent. However, the resulting iron(II) can be used to continuously regenerate iron(0) when a potential is applied to the glassy carbon working electrode. Controlled potential electrolysis experiments show a 17% conversion of cyclohexanone (over 1000 seconds) to cyclohexanol with >80% efficiency of iron deposition from an iron(II) sulfate solution containing formic or sulfuric acid. In the absence of electrodeposited iron, formation of cyclohexanol could not be detected.
Electrodeposition of lead on glassy carbon and mercury film electrodes from a distillable room temperature ionic liquid, DIMCARB
Publisher: Springer Science and Business Media LLC
Date: 12-09-2007
Investigation of cupric ion extraction kinetics in a two-phase organic/water system using microelectrochemical measurements at expanding droplets (MEMED)
Publisher: Elsevier BV
Date: 12-2002
Microelectrochemical measurements of electron transfer rates at the interface between two immiscible electrolyte solutions: Potential dependence of the ferro/ferricyanide-7,7,8,8-tetracyanoquinodimeth
Publisher: Royal Society of Chemistry (RSC)
Date: 04-07-2002
DOI: 10.1039/B108882C
Selective Electrochemical Hydrogenation of Phenol with Earth-abundant Ni−MoO2 Heterostructured Catalysts: Effect of Oxygen Vacancy on Product Selectivity
Publisher: Wiley
Date: 18-01-2023
Abstract: Herein, we report highly efficient carbon supported Ni−MoO 2 heterostructured catalysts for the electrochemical hydrogenation (ECH) of phenol in 0.10 M aqueous sulfuric acid (pH 0.7) at 60 °C. Highest yields for cyclohexanol and cyclohexanone of 95 % and 86 % with faradaic efficiencies of ∼50 % are obtained with catalysts bearing high and low densities of oxygen vacancy (O v ) sites, respectively. In situ diffuse reflectance infrared spectroscopy and density functional theory calculations reveal that the enhanced phenol adsorption strength is responsible for the superior catalytic efficiency. Furthermore, 1‐cyclohexene‐1‐ol is an important intermediate. Its hydrogenation route and hence the final product are affected by the O v density. This work opens a promising avenue to the rational design of advanced electrocatalysts for the upgrading of phenolic compounds.
Variation of Carbon Based Materials on the Electropolymerization of Tyramine
Publisher: Wiley
Date: 24-05-2018
Diminished Electron Transfer Kinetics for Ru(NH3)(6) (3+/2+), alpha-SiW12O40 (4-/5-), and alpha-SiW12O40 (5-/6-) Processes at Boron-Doped Diamond Electrodes
Publisher: American Chemical Society (ACS)
Date: 19-05-2015
Determination of ytterbium using electrothermal atomic absorption spectrometry with europium as chemical modifier
Publisher: Royal Society of Chemistry (RSC)
Date: 1995
DOI: 10.1039/AN9952001661
A randomised trial of intracavitary electrocardiography versus surface landmark measurement for central venous access device placement
Publisher: SAGE Publications
Date: 08-04-2022
DOI: 10.1177/11297298221085228
Abstract: Malpositioned central venous access devices (CVADs) can lead to significant patient injury including central vein thrombosis and dysrhythmias. Intra-cavitary electrocardiography (IC ECG) has been recommended by peak professional bodies as an accurate alternative for bedside CVAD insertion, to reduce risk of malposition and allowing immediate use of the device. Our objective was to compare the effect of IC ECG on CVAD malposition compared to traditional institutional practice for CVAD placement. Randomised controlled trial of IC ECG CVAD insertion verses traditional CVAD insertion (surface landmark measurement with post insertion x ray). Patient recruitment was from December 2016 to July 2018. The setting was a 900-bed tertiary referral hospital based in South Western Sydney, Australia. Three hundred and forty-four adult patients requiring CVAD insertion for intravenous therapy, were enrolled and randomly allocated (1:1 ratio) to either IC-ECG ( n = 172) or traditional ( n = 172) CVAD insertion. Our primary outcome of interest was the rate of catheters not requiring repositioning after insertion (ready for use). Secondary outcomes were comparison of procedure time and cost. Of the 172 patients allocated to the IC ECG method, 170 (99%) were ready for use immediately compared to 139 of the 172 (81%) in the traditional insertion group (difference, 95% confidence interval (CI): 18%, 11.9–24.1%). The total procedure time was mean 15 min (SD 8 min) for IC ECG and mean 36 min (SD 17 min) for traditional CVAD insertion (difference–19.9 min (95% CI–14.6 to −34.4). IC ECG guided CVAD insertion had a cost reduction of AUD $62.00 per procedure. Using IC-ECG resulted in nearly no requirement for post-insertion repositioning of CVADs resulting in savings in time and cost and virtually eliminating the need for radiographic confirmation. This trial is registered at the Australian New Zealand Clinical Trials Registry ( www.anzctr.org.au ). The registration number is ACTRN12620000919910.
Microelectrochemical measurements at expanding droplets (MEMED): investigation of cupric ion stripping kinetics in a two-phase oil/water system
Publisher: Royal Society of Chemistry (RSC)
Date: 2000
DOI: 10.1039/A909374E
Ionic liquids and their solid-state analogues as materials for energy generation and storage
Publisher: Springer Science and Business Media LLC
Date: 12-01-2016
Application of Bayesian Inference in Fourier-Transformed Alternating Current Voltammetry for Electrode Kinetic Mechanism Distinction
Publisher: American Chemical Society (ACS)
Date: 18-03-2019
DOI: 10.1021/ACS.ANALCHEM.9B00129
Abstract: Estimation of parameters of interest in dynamic electrochemical (voltammetric) studies is usually undertaken via heuristic or data optimization comparison of the experimental results with theory based on a model chosen to mimic the experiment. Typically, only single point parameter values are obtained via either of these strategies without error estimates. In this article, Bayesian inference is introduced to Fourier-transformed alternating current voltammetry (FTACV) data analysis to distinguish electrode kinetic mechanisms (reversible or quasi-reversible, Butler-Volmer or Marcus-Hush models) and quantify the errors. Comparisons between experimental and simulated data were conducted across all harmonics using public domain freeware (MECSim).
Utilization of nanoparticle labels for signal amplification in ultrasensitive electrochemical affinity biosensors: A review
Publisher: Elsevier BV
Date: 10-2013
DOI: 10.1016/J.ACA.2013.07.035
Abstract: Nanoparticles with desirable properties not exhibited by the bulk material can be readily synthesized because of rapid technological developments in the fields of materials science and nanotechnology. In particular their highly attractive electrochemical properties and electrocatalytic activity have facilitated achievement of the high level of signal lification needed for the development of ultrasensitive electrochemical affinity biosensors for the detection of proteins and DNA. This review article explains the basic principles of nanoparticle based electrochemical biosensors, highlights the recent advances in the development of nanoparticle based signal lification strategies, and provides a critical assessment of the likely drawbacks associated with each strategy. Finally, future perspectives for achieving advanced signal simplification in nanoparticles based biosensors are considered.
A doubly amplified electrochemical immunoassay for carcinoembryonic antigen
Publisher: Elsevier BV
Date: 03-2009
DOI: 10.1016/J.BIOS.2008.09.009
Abstract: An ultrasensitive electrochemical immunoassay (EIA) for the detection of carcinoembryonic antigen (CEA) is described in this report. The assay involves utilizing enzyme-catalyzed deposition of a redox polymer and electrocatalytic oxidation of ascorbic acid (AA) by the deposited redox polymer, a dual- lification scheme to enhance analytical signals. Briefly, CEA capturing antibody and redox polymer anchoring agent were covalently immobilized on a gold electrode. After incubating with CEA, the electrode was treated in detection antibody-glucose oxidase conjugate solution. Thereafter, it was dipped into the redox polymer solution. Upon the addition of glucose, the redox polymer was enzymatically reduced and deposited on the electrode surface. The deposited redox polymer exhibits excellent electrocatalytic activity towards the oxidation of AA. Consequently, CEA could be quantified erometrically. This electrochemical immunoassay combines the specificity of the immunological reaction with the sensitivity of the doubly lified electrochemical detection.
Microelectrochemical studies of charge transfer at the interface between two immiscible electrolyte solutions: electron transfer from decamethyl ferrocene to aqueous oxidants
Publisher: Elsevier BV
Date: 03-2000
An introduction to Bayes’ theorem and examples of its application to a diagnostic test and a clinical trial
Publisher: RCN Publishing Ltd.
Date: 10-03-2022
Influences of the operative parameters and the nature of the substrate on the electrocarboxylation of benzophenones
Publisher: Elsevier BV
Date: 2012
Microelectrochemical Measurements at Expanding Droplets: Effect of Surfactant Adsorption on Electron Transfer Kinetics at Liquid/Liquid Interfaces
Publisher: American Chemical Society (ACS)
Date: 06-01-2001
DOI: 10.1021/LA001113Z
Efficient strategy for quality control of screen-printed carbon ink disposable sensor electrodes based on simultaneous evaluation of resistance, capacitance and Faradaic current by Fourier transform AC voltammetry
Publisher: Springer Science and Business Media LLC
Date: 07-03-2008
The Origin of the Electrocatalytic Activity for CO2 Reduction Associated with Metal‐Organic Frameworks
Publisher: Wiley
Date: 07-04-2020
Formulations of selected Energy beverages promote pro-oxidant effects of ascorbic acid and long-term stability of hydrogen peroxide
Publisher: Elsevier BV
Date: 09-2022
Detailed analysis of the electron-transfer properties of azurin adsorbed on graphite electrodes using dc and large-amplitude Fourier transformed ac voltammetry
Publisher: American Chemical Society (ACS)
Date: 02-08-2007
DOI: 10.1021/AC070448J
Abstract: The analysis of dc cyclic voltammograms of surface-confined metalloproteins is complicated by large background currents, significant ohmic iRu drop, and frequency dispersion related to protein and electrode surface inhomogeneity. The use of large- litude Fourier transform ac voltammetry for the quantification of the electron-transfer properties of a thin film of redox-active protein azurin adsorbed onto edge-plane, basal-plane, and highly oriented pyrolytic graphite electrode surfaces has been evaluated and compared to results obtained by dc cyclic voltammetry. In principle, it has been established that fourth and higher harmonic sine-wave data are ideally suited for analysis of electron-transfer processes as they are almost completely devoid of background capacitance current contributions. However, uncompensated resistance has a higher impact on these components, as is the case with fast scan rate dc techniques, so strategies to include this term in the simulations have been investigated. Application of recommended strategies for the evaluation of the electron-transfer properties of azurin adsorbed onto three forms of graphite, each having different background or uncompensated resistance values, is described and compared to results obtained by traditionally used forms of cyclic voltammetry. The electron-transfer rate constant, k0', of azurin at a highly oriented pyrolytic graphite electrode surface was approximately 250 s(-1), compared with > or =1000 s(-1) at edge-plane and basal-plane graphite electrodes. The significantly lower k0' value found at the highly oriented pyrolytic graphite electrode was related to the relatively low level of edge-plane defect sites present at the surface of this electrode. However, analysis of high ac harmonics suggests that frequency dispersion is substantial at all electrode surfaces. Such effects in these diffusionless situations are significantly enhanced relative to solution-phase voltammetry, where overlay of diffusion layers minimizes the impact of heterogeneity.
Detailed Electrochemical Studies of the Tetraruthenium Polyoxometalate Water Oxidation Catalyst in Acidic Media: Identification of an Extended Oxidation Series using Fourier Transformed Alternating Cu
Publisher: American Chemical Society (ACS)
Date: 23-10-2012
DOI: 10.1021/IC301370Y
Abstract: The electrochemistry of the water oxidation catalyst, Rb(8)K(2)[{Ru(4)O(4)(OH)(2)(H(2)O)(4)}(γ-SiW(10)O(36))(2)] (Rb(8)K(2)-1(0)) has been studied in the presence and absence of potassium cations in both hydrochloric and sulfuric acid solutions by transient direct current (dc) cyclic voltammetry, a steady state dc method in the rotating disk configuration and the kinetically sensitive technique of Fourier transformed large- litude alternating current (ac) voltammetry. In acidic media, the presence of potassium ions affects the kinetics (apparent rate of electron transfer) and thermodynamics (reversible potentials) of the eight processes (A'/A to H/H') that are readily detected under dc voltammetric conditions. The six most positive processes (A'/A to F/F'), each involve a one electron ruthenium based charge transfer step (A'/A, B'/B are Ru(IV/V) oxidation and C/C' to F/F' are Ru(IV/III) reduction). The apparent rate of electron transfer of the ruthenium centers in sulfuric acid is higher than in hydrochloric acid. The addition of potassium cations increases the apparent rates and gives rise to a small shift of reversible potential. Simulations of the Fourier transformed ac voltammetry method show that the B'/B, E/E', and F/F' processes are quasi-reversible, while the others are close to reversible. A third Ru(IV/V) oxidation process is observed just prior to the positive potential limit via dc methods. Importantly, the ability of the higher harmonic components of the ac method to discriminate against the irreversible background solvent process allows this (process I) as well as an additional fourth reversible ruthenium based process (J) to be readily identified. The steady-state rotating disk electrode (RDE) method confirmed that all four Ru-centers in Rb(8)K(2)-1(0) are in oxidation state IV. The dc and ac data indicate that reversible potentials of the four ruthenium centers are evenly spaced, which may be relevant to understanding of the water oxidation electrocatalysis. A profound effect of the potassium cation is observed for the one-electron transfer process (G/G') assigned to Ru(III/II) reduction and the multiple electron transfer reduction process (H/H') that arise from the tungstate polyoxometalate framework. A significant shift of E°' to a more positive potential value for process H/H' was observed on removal of K(+) (~100 mV in H(2)SO(4) and ~50 mV in HCl).
Resistance, Capacitance, and Electrode Kinetic Effects in Fourier-Transformed Large-Amplitude Sinusoidal Voltammetry: Emergence of Powerful and Intuitively Obvious Tools for Recognition of Patterns o
Publisher: American Chemical Society (ACS)
Date: 25-09-2004
DOI: 10.1021/AC0495337
Abstract: Large- litude sinusoidal ac voltammetric techniques, when analyzed in the frequency domain using the Fourier transform-inverse Fourier transform sequence, produce the expected dc and fundamental harmonic ac responses in addition to very substantial second, third, and higher ac harmonics that arise from the presence of significant nonlinearity. A full numerical simulation of the process, Red right arrow over left arrow Ox + e(-), incorporates terms for the uncompensated resistance (R(u)), capacitance of the double layer (C(dl)), and slow electron transfer kinetics (in particular, the reversible potential (E degrees ), rate constant (k(0)), and charge transfer coefficient (alpha) from the Butler-Volmer model). Identification of intuitively obvious patterns of behavior (with characteristically different sensitivity regimes) in dc, fundamental, and higher harmonic terms enables simple protocols to be developed to estimate R(u), C(dl), E degrees , k(0), and alpha. Thus, if large- litude sinusoidal cyclic voltammograms are obtained for two concentrations of the reduced species, data obtained from analysis of the recovered signals provide initial estimates of parameters as follows: (a) the dc cyclic component provides an estimate of E degrees (because the R(u) and k(0) effects are minimized) (b) the fundamental harmonic provides an estimate of C(dl) (because it has a high capacitance-to-faradaic current ratio) and (c) the second harmonic provides an estimate of R(u), k(0), and alpha (because the C(dl) effect is minimized). Methods of refining the initial estimates are then implemented. As a check on the fidelity of the parameters (estimated on the basis of an essentially heuristic approach that solely utilizes the dc, fundamental, and second harmonic voltammograms), comparison of the predicted simulated and experimental third (or higher) harmonic voltammograms can be made to verify that agreement between theory and experiment has been achieved at a predetermined level. The use of the heuristic pattern recognition approach to evaluate the oxidation of ferrocene at a platinum electrode (a reversible process) in the very high resistance solvent dichloromethane (0.1 M Bu(4)NPF(6)) and the reduction of [Fe(CN(6))](3)(-) at a glassy carbon electrode (a quasi-reversible process) in much lower resistance but higher capacitance conditions found in aqueous (0.5 M KCl) media is described and verifies the inherent advantages of employing large- litude sinusoidal techniques in quantitative studies of electrode processes.
Inclusion of multiple cycling of potential in the deep neural network classification of voltammetric reaction mechanisms
Publisher: Royal Society of Chemistry (RSC)
Date: 2021
DOI: 10.1039/D1FD00050K
Abstract: Deep neural networks applied to three cycle voltammograms showed significant advantages in classifying difficult simulated E, EC 1 st and EC 2 nd processes.
Atomic nickel cluster decorated defect-rich copper for enhanced C2 product selectivity in electrocatalytic CO2 reduction
Publisher: Elsevier BV
Date: 08-2021
Voltammetric studies of polyoxometalate microparticles in contact with the reactive distillable ionic liquid DIMCARB
Publisher: Elsevier BV
Date: 12-2005
Interfacial polymerisation of anilinium at Langmuir monolayers
Publisher: Royal Society of Chemistry (RSC)
Date: 2004
DOI: 10.1039/B312858J
Abstract: Anilinium is strongly adsorbed at monolayers of the phospholipid L-alpha-dimyristoylphosphatidic acid (DMPA) and hexadecanesulfonic acid (HDSA) at the air-water interface, and undergoes chemical polymerisation under conditions where bulk polymerisation does not occur.
Electrochemical Hydrogenation of Furfural in Aqueous Acetic Acid Media with Enhanced 2‐Methylfuran Selectivity Using CuPd Bimetallic Catalysts
Publisher: Wiley
Date: 03-02-2022
Abstract: Herein, we report a series of CuPd catalysts for electrochemical hydrogenation (ECH) of furfural to 2‐methylfuran (MF or FurCH 3 where Fur=furyl) in aqueous 0.1 M acetic acid (pH 2.9). The highest faradaic efficiency (FE) for MF reached 75 % at −0.58 V vs. reversible hydrogen electrode with an average partial current density of 4.5 mA cm −2 . In situ surface‐enhanced Raman spectroscopic and kinetic isotopic experiments suggested that electrogenerated adsorbed hydrogen (H ads ) was involved in the reaction and incorporation of Pd enhanced the surface coverage of H ads and optimized the adsorption pattern of furfural, leading to a higher FE for MF. Density functional theory calculations revealed that Pd incorporation reduced the energy barrier for the hydrogenation of FurCH 2 * to FurCH 3 *. Our study demonstrates that catalyst surface structure/composition plays a crucial role in determining the selectivity in ECH and provides a new strategy for designing advanced catalysts for ECH of bio‐derived oxygenates.
Conditions required to achieve the apparent equivalence of adhered solid- and solution-phase voltammetry for ferrocene and other redox-active solids in ionic liquids
Publisher: American Chemical Society (ACS)
Date: 03-05-2003
DOI: 10.1021/AC026329F
Abstract: The voltammetry of ferrocene (Fc) and Fc+ in the room-temperature ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate (BMIM x PF6) has been studied when solid is adhered to glassy carbon or platinum disk electrodes. Due to the slow dissolution kinetics and small diffusion coefficients in the viscous BMIM x PF6 ionic liquid, it is possible to obtain voltammograms of adhered Fc or Fc+ solid that are essentially indistinguishable (except for the current magnitude) from the reversible solution-phase Fc(0/+) process widely employed to provide a reference potential scale. However, the nature of the voltammetry obtained from the adhered solid is governed by the thickness (mass of the solid) of the particle layer. The mechanism proposed to explain the equivalence to solution-phase data involves dissolution at the particle/ionic liquid interface and is supported by electrochemical quartz microbalance measurements and a numerical simulation. Extensive studies on other redox-active solids suggest that voltammograms of solid particles adhered to the electrode surface in contact with ionic liquids frequently exhibit classical behavior associated with solution-phase diffusion-controlled voltammetry. Consequently, the method of adhering microparticles onto an electrode surface can frequently provide an efficient method of establishing ionic liquid solution-phase redox data using extremely small quantities of solid.
Using Purely Sinusoidal Voltammetry for Rapid Inference of Surface-Confined Electrochemical Reaction Parameters
Publisher: American Chemical Society (ACS)
Date: 08-01-2021
Oxomolybdate anchored on copper for electrocatalytic hydrogen production over the entire pH range
Publisher: Elsevier BV
Date: 07-2019
Changing the Look of Voltammetry
Publisher: American Chemical Society (ACS)
Date: 05-2005
DOI: 10.1021/AC053370K
Systematic evaluation of electrode kinetics and impact of surface heterogeneity for surface-confined proteins using analysis of harmonic components available in sinusoidal large-amplitude Fourier tran
Publisher: Elsevier BV
Date: 10-2009
DOI: 10.1016/J.ACA.2009.05.015
Abstract: A systematic approach to quantifying the electrode kinetics of surface-confined proteins and identifying the impact of surface heterogeneity is presented. The evaluation approach is based on analysis of in idual harmonics derived from Fourier transformed large- litude ac voltammetry, and their peak current magnitude, I(p)(nomegat) versus frequency, f, relationships. Effectively, variability in the time-scale of each harmonic is expected, and advantage is taken of the fact that each in idual harmonic displays a different level of sensitivity with respect to the kinetic evaluation. The data strategy protocols have been examined for the azurin Cu(II)/Cu(I) process when this metalloprotein is immobilized on gold electrodes modified alkanethiols having different chain lengths, using both pure and mixed thiol systems. I(p)(nomegat) versusf relationships also offer the advantage of the ability to detect and allow for the ohmic IR(u) drop effect and allow analyses that are independent of protein surface coverage. Estimation of an electron transfer rate is achievable from this form of analysis. However, experimentally observed waveshapes for each in idual harmonic are consistently broader than that deduced theoretically on the basis of their rate constants because of kinetic and/or thermodynamic dispersion. In the mixed thiol systems, and with use of the ac method, kinetic discrimination is achieved for fast processes. This systematic study based on a model protein indicates that a more comprehensive level of evaluation of electrode kinetics can be derived from analysis of the ac harmonics available in large- litude ac voltammetry, by initially using I(p)(nomegat)-f data to evaluate the electrode kinetics followed by waveshape analysis to detect heterogeneity effects that give rise to kinetic or thermodynamic dispersion.
TiO2 nanocrystal rods on titanium microwires: growth, vacuum annealing, and photoelectrochemical oxygen evolution
Publisher: Royal Society of Chemistry (RSC)
Date: 2022
DOI: 10.1039/D2NJ00045H
Abstract: Titania nanocrystal rods grown hydrothermally onto titanium microwire are mechanically robust and photoelectrochemically active.
Investigation of the kinetics of electron transfer processes involving fullerenes at liquid–liquid interfaces using scanning electrochemical microscopy: evidence for Marcus inverted region behaviour
Publisher: Royal Society of Chemistry (RSC)
Date: 2001
DOI: 10.1039/B102734B
Simplifying the Evaluation of Graphene Modified Electrode Performance Using Rotating Disk Electrode Voltammetry
Publisher: American Chemical Society (ACS)
Date: 07-03-2012
DOI: 10.1021/LA205013N
Abstract: Graphene modified electrodes have been fabricated by electrodeposition from an aqueous graphene oxide solution onto conducting Pt, Au, glassy carbon, and indium tin dioxide substrates. Detailed investigations of the electrochemistry of the [Ru(NH(3))(6)](3+/2+) and [Fe(CN)(6)](3-/4-) and hydroquinone and uric acid oxidation processes have been undertaken at glassy carbon and graphene modified glassy carbon electrodes using transient cyclic voltammetry at a stationary electrode and near steady-state voltammetry at a rotating disk electrode. Comparisons of the data with simulation suggest that the transient voltammetric characteristics at graphene modified electrodes contain a significant contribution from thin layer and surface confined processes. Consequently, interpretations based solely on mass transport by semi-infinite linear diffusion may result in incorrect conclusions on the activity of the graphene modified electrode. In contrast, steady-state voltammetry at a rotating disk electrode affords a much simpler method for the evaluation of the performance of graphene modified electrode since the relative importance of the thin layer and surface confined processes are substantially diminished and mass transport is dominated by convection. Application of the rotated electrode approach with carbon nanotube modified electrodes also should lead to simplification of data analysis in this environment.
Combined scanning electrochemical microscopy–Langmuir trough technique for investigating phase transfer kinetics across liquid/liquid interfaces modified by a molecular monolayer
Publisher: Elsevier BV
Date: 02-2003
Polystyrenesulfonate doped poly(Hydroxymethyl 3,4-Ethylenedioxythiophene) stabilized Au nanoparticle modified glassy carbon electrode as a reusable sensor for mercury(II) detection in chloride media
Publisher: Elsevier BV
Date: 09-2013
Direct Detection of Electron Transfer Reactions Underpinning the Tin-Catalyzed Electrochemical Reduction of CO2 using Fourier-Transformed ac Voltammetry
Publisher: American Chemical Society (ACS)
Date: 23-06-2017
Comparison of voltammetric data obtained for the trans- Mn(CN)(CO)(2){P(OPh)3}(Ph2PCH2PPh2) (0/+) process in BMIM center dot PF6 ionic liquid under microchemical and conventional conditions
Publisher: American Chemical Society (ACS)
Date: 11-11-2003
DOI: 10.1021/AC034921E
Abstract: Conventional cyclic voltammetric studies on the oxidation of millimolar concentrations (mg masses) of trans-[Mn(CN)(CO)(2)[P(OPh)(3)](Ph(2)PCH(2)PPh(2))] (trans-Mn) dissolved in milliliter volumes of bulk ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate (BMIM.PF(6)), give rise to a reversible [trans-Mn](0/+) process. In this study, it is shown that equally well-defined reversible voltammetry can be more economically obtained under microchemical ionic liquid conditions by employing a chemically modified electrode (microg quantities of trans-Mn adhered to a glassy carbon electrode covered with microliter volumes of water-immiscible BMIM.PF(6)) in contact with aqueous (0.1 M KPF(6)) electrolyte. The ability to obtain electrochemical data that are directly relatable to bulk ionic liquid media under these microchemical conditions is principally associated with the dissolution of electrogenerated solid [trans-Mn](+) in the layer of water-immiscible BMIM.PF(6) present at the electrode/ionic liquid/aqueous electrolyte interface. If the BMIM.PF(6) layer is sufficiently thick, mass transport of the dissolved species is governed by semi-infinite linear diffusion. Under these conditions, the voltammetric waveshape and position, but not the current magnitude are the same as those found when conventional bulk ionic liquid conditions are employed. In contrast, use of very thin layers produces voltammograms that exhibit the characteristics expected for a reversible process in which the mass transport process is predominantly governed by finite rather than semi-infinite diffusion. A theoretical model has been developed that describes the transformation from thick- to thin-layer type behavior as the thickness of the ionic liquid layer is decreased.
On choosing a reference redox system for electrochemical measurements: a cautionary tale
Publisher: Springer Science and Business Media LLC
Date: 24-07-2013
Stepping towards Solar Water Splitting: Recent Progress in Bismuth Vanadate Photoanodes
Publisher: Wiley
Date: 15-05-2019
Impact of the Lithium Cation on the Voltammetry and Spectroscopy of [XVM11O40]n− (X = P, As (n = 4), S (n = 3); M = Mo, W): Influence of Charge an
Publisher: American Chemical Society (ACS)
Date: 17-06-2020
Formation of lattice-dislocated bismuth nanowires on copper foam for enhanced electrocatalytic CO2 reduction at low overpotential
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C9EE00018F
Abstract: Twisted bismuth nanowire (BiNW) with abundant crystal lattice dislocations is a highly active electrocatalyst for CO 2 reduction to formate at low overpotential.
Integration of Heuristic and Automated Parametrization of Three Unresolved Two‐Electron Surface‐Confined Polyoxometalate Reduction Processes by AC Voltammetry
Publisher: Wiley
Date: 11-10-2018
Practical considerations associated with voltammetric studies in room temperature ionic liquids
Publisher: Royal Society of Chemistry (RSC)
Date: 2005
DOI: 10.1039/B504721H
Abstract: Recent developments associated with voltammetric studies in ionic liquid media have been critically reviewed. Initially, advantageous electrochemical properties of ionic liquids are summarised, as are limitations encountered by the presence of impurities and problems related to purification and recovery of ionic liquids. Subsequently, the use of IUPAC recommended ferrocene oxidation and cobalticenium reduction processes as potential reference scales in ionic liquids and the application of voltammetry of adhered solid and microchemical approaches to the measurement of formal potentials and kinetics of coupled first order chemical reactions are discussed. Finally, the possible use of volatile ionic liquids is considered as an alternative to use of the non-volatile ionic liquids media, presently emphasized in most studies.
Electrolyte cation dependence of the electron transfer kinetics associated with the [SVW11O40]3–/4– (VV/IV) and [SVW11O40]4–/5– (WVI/V) processes in propylene carbonate
Publisher: Elsevier BV
Date: 06-2018
Electrochemical studies on the modular podand 1,3,5-tris(3-((ferrocenylmethyl)amino)pyridiniumyl)-2,4,6-triethylbenzen e hexafluorophosphate in conventional solvents and ionic liquids
Publisher: American Chemical Society (ACS)
Date: 24-05-2003
DOI: 10.1021/JP027699A
Fourier-Transformed Large-Amplitude AC Voltammetric Study of Tetrathiafulvalene (TTF): Electrode Kinetics of the TTF0/TTFC center dot+ and TTFC center dot+/TTF2+ Processes
Publisher: Wiley
Date: 06-11-2014
Conversion of dinitrogen to ammonia on Ru atoms supported on boron sheets: a DFT study
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C8TA08219G
Abstract: By first-principles computations, nitrogen becomes activated via distal pathway on the single Ru-atom-embedded two boron monolayers, exhibiting relatively low reaction energy barriers of 0.42 and 0.44 eV, respectively.
Towards a better Sn: Efficient electrocatalytic reduction of CO 2 to formate by Sn/SnS 2 derived from SnS 2 nanosheets
Publisher: Elsevier BV
Date: 2017
Advanced Spatiotemporal Voltammetric Techniques for Kinetic Analysis and Active Site Determination in the Electrochemical Reduction of CO2
Publisher: American Chemical Society (ACS)
Date: 12-01-2022
DOI: 10.1021/ACS.ACCOUNTS.1C00617
Abstract: ConspectusElectrochemical reduction of the greenhouse gas CO
Use of Bayesian Inference for Parameter Recovery in DC and AC Voltammetry
Publisher: Wiley
Date: 19-10-2017
Determination of fast electrode kinetics facilitated by use of an internal reference
Publisher: American Chemical Society (ACS)
Date: 06-08-2015
DOI: 10.1021/ACS.ANALCHEM.5B01667
Abstract: The concept of using an internal reversible reference process as a calibration in the determination of fast electrode kinetics has been developed and applied with the technique of Fourier transformed large litude ac voltammetry to minimize the influence of errors arising from uncertainties in parameters such as electrode area (A), concentration (C), diffusion coefficient (D), and uncompensated resistance (Ru). Since kinetic parameters (electron transfer rate constant, k(0), and electron transfer coefficient, α) are irrelevant in the voltammetric characterization of a reversible reaction, parameters such as A, C, D, and Ru can be calibrated using the reversible process prior to quantification of the electrode kinetics associated with the fast quasi-reversible process. If required, new values of parameters derived from the calibration exercise can be used for the final determination of k(0) and α associated with the process of interest through theory-experimental comparison exercises. Reference to the reversible process is of greatest significance in diminishing the potentially large impact of systematic errors on the measurement of electrode kinetics near the reversible limit. Application of this method is demonstrated with respect to the oxidation of tetrathiafulvalene (TTF), where the TTF(0/•+) process is used as a reversible internal reference for the measurement of the quasi-reversible kinetics of the TTF(•+/2+) process. The more generalized concept is demonstrated by use of the Fc(0/+) (Fc = ferrocene) reversible process as an internal reference for measurement of the kinetics of the Cc(+/0) (Cc(+) = cobaltocenium) process. Via the internal reversible reference approach, a k(0) value of 0.55 cm s(-1) was obtained for the TTF(•+/2+) process at a glassy carbon electrode and 2.7 cm s(-1) for the Cc(+/0) one at a carbon fiber microelectrode in acetonitrile (0.1 M Bu4NPF6).
Prediction of disability-free survival in healthy older people
Publisher: Springer Science and Business Media LLC
Date: 14-04-2022
DOI: 10.1007/S11357-022-00547-X
Abstract: Prolonging survival in good health is a fundamental societal goal. However, the leading determinants of disability-free survival in healthy older people have not been well established. Data from ASPREE, a bi-national placebo-controlled trial of aspirin with 4.7 years median follow-up, was analysed. At enrolment, participants were healthy and without prior cardiovascular events, dementia or persistent physical disability. Disability-free survival outcome was defined as absence of dementia, persistent disability or death. Selection of potential predictors from amongst 25 biomedical, psychosocial and lifestyle variables including recognized geriatric risk factors, utilizing a machine-learning approach. Separate models were developed for men and women. The selected predictors were evaluated in a multivariable Cox proportional hazards model and validated internally by bootstrapping. We included 19,114 Australian and US participants aged ≥65 years (median 74 years, IQR 71.6–77.7). Common predictors of a worse prognosis in both sexes included higher age, lower Modified Mini-Mental State Examination score, lower gait speed, lower grip strength and abnormal (low or elevated) body mass index. Additional risk factors for men included current smoking, and abnormal eGFR. In women, diabetes and depression were additional predictors. The biased-corrected areas under the receiver operating characteristic curves for the final prognostic models at 5 years were 0.72 for men and 0.75 for women. Final models showed good calibration between the observed and predicted risks. We developed a prediction model in which age, cognitive function and gait speed were the strongest predictors of disability-free survival in healthy older people. Trial registration Clinicaltrials.gov (NCT01038583)
Scanning Electrochemical Microscopy (SECM) Studies of Oxygen Transfer across Phospholipid Monolayers under Surface Pressure Control: Comparison of Monolayers at Air/Water and Oil/Water Interfaces
Publisher: American Chemical Society (ACS)
Date: 08-01-2004
DOI: 10.1021/LA034943W
Abstract: Scanning electrochemical microscopy has been used in combination with a specially designed Langmuir trough to compare the kinetics of oxygen transfer across an L-alpha-phosphatidylethanolamine, distearoyl monolayer spread at three different interfaces: air/water, air/water in contact with an oil lens, and oil/water. The monolayer is shown to reduce the kinetics of interfacial transport, and rate constants for the transport of oxygen across each interface, at different surface pressures, have been evaluated. The results obtained for each interface are compared, and the implications for studies of passive diffusion across cell membranes are discussed.
Production of hydrogen peroxide in formulated beverages is associated with the presence of ascorbic acid combined with selected redox-active functional ingredients
Publisher: Elsevier BV
Date: 02-2021
Double-Layer Capacitance at Ionic Liquid-Boron-Doped Diamond Electrode Interfaces Studied by Fourier Transformed Alternating Current Voltammetry
Publisher: American Chemical Society (ACS)
Date: 10-05-2018
Electrode Kinetics Associated with Tetracyanoquinodimethane (TCNQ), TCNQ(center dot-), and TCNQ(2-) Redox Chemistry in Acetonitrile As Determined by Analysis of Higher Harmonic Components Derived from Fourier Transformed Large Amplitude ac Voltammetry
Publisher: American Chemical Society (ACS)
Date: 15-11-2011
DOI: 10.1021/JP2072793
PdCu@Pd Nanocube with Pt-like Activity for Hydrogen Evolution Reaction
Publisher: American Chemical Society (ACS)
Date: 27-02-2017
Abstract: The electronic properties of metal surfaces can be modulated to weaken the binding energy of adsorbed H-intermediates on the catalyst surface, thus enhancing catalytic activity for the hydrogen evolution reaction (HER). Here we first prepare PdCu alloy nanocubes (NCs) by coreduction of Cu(acac)
Controllable Synthesis of Few‐Layer Bismuth Subcarbonate by Electrochemical Exfoliation for Enhanced CO2 Reduction Performance
Publisher: Wiley
Date: 03-09-2018
Abstract: Two‐dimensional (2D) engineering of materials has been recently explored to enhance the performance of electrocatalysts by reducing their dimensionality and introducing more catalytically active ones. In this work, controllable synthesis of few‐layer bismuth subcarbonate nanosheets has been achieved via an electrochemical exfoliation method. These nanosheets catalyse CO 2 reduction to formate with high faradaic efficiency and high current density at a low overpotential owing to the 2D structure and co‐existence of bismuth subcarbonate and bismuth metal under catalytic turnover conditions. Two underlying fast electron transfer processes revealed by Fourier‐transformed alternating current voltammetry (FTacV) are attributed to CO 2 reduction at bismuth subcarbonate and bismuth metal. FTacV results also suggest that protonation of CO 2 .− is the rate determining step for bismuth catalysed CO 2 reduction.
Oxidation of 4-Methylanisole by Aqueous Cerium(IV) in a Two−Phase Immiscible Liquid/Liquid System: Interfacial versus Homogeneous Control
Publisher: American Chemical Society (ACS)
Date: 26-02-2002
DOI: 10.1021/JP013818V
Mass-Transport and Heterogeneous Electron-Transfer Kinetics Associated with the Ferrocene/Ferrocenium Process in Ionic Liquids
Publisher: American Chemical Society (ACS)
Date: 20-07-2016
Hydrophobicity Graded Gas Diffusion Layer for Stable Electrochemical Reduction of CO2
Publisher: Wiley
Date: 23-08-2022
Abstract: To mitigate flooding associated with the gas diffusion layer (GDL) during electroreduction of CO 2 , we report a hydrophobicity‐graded hydrophobic GDL (HGGDL). Coating uniformly dispersed polytetrafluoroethylene (PTFE) binders on the carbon fiber skeleton of a hydrophilic GDL uniformizes the hydrophobicity of the GDL and also alleviates the gas blockage of pore channels. Further adherence of the PTFE macroporous layer (PMPL) to one side of the hydrophobic carbon fiber skeleton was aided by sintering. The introduced PMPL shows an appropriate pore size and enhanced hydrophobicity. As a result, the HGGDL offers spatial control of the hydrophobicity and hence water and gas transport over the GDL. Using a nickel‐single‐atom catalyst, the resulting HGGDL electrode provided a CO faradaic efficiency of over 83 % at a constant current density of 75 mA cm −2 for 103 h operation in a membrane electrode assembly, which is more than 16 times that achieved with a commercial GDL.
Effect of Surface Pressure on the Insulator to Metal Transition of a Langmuir Polyaniline Monolayer
Publisher: American Chemical Society (ACS)
Date: 15-07-2003
DOI: 10.1021/JA036146Q
Abstract: A remarkable change in the conductivity of a polyaniline (PAN) Langmuir monolayer in the conducting state, as a function of surface pressure, has been observed using scanning electrochemical microscopy (SECM). The film conductivity, as expressed by the SECM current response of a redox mediator, was measured in-situ in a Langmuir film balance. The conductivity of the film increases significantly with surface pressure, above a threshold value of ca. 20 mN m-1.
The role of dissolution in the voltammetry of microdroplets and microparticles adhered to electrode surfaces in contact with aqueous electrolytes or ionic liquids
Publisher: Elsevier BV
Date: 2005
Prospects for a widely applicable reference potential scale in ionic liquids based on ideal reversible reduction of the cobaltocenium cation
Publisher: Elsevier BV
Date: 02-2008
Advantages available in the application of the semi-integral electroanalysis technique for the determination of diffusion coefficients in the highly viscous ionic liquid 1-methyl-3-octylimidazolium hexafluorophosphate
Publisher: American Chemical Society (ACS)
Date: 30-01-2013
DOI: 10.1021/AC303042R
Spectroscopic Insights into the Mechanism of Selective Catalytic Reduction of NO by Ammonia on Sulfuric Acid‐modified Fe2O3 Surface
Publisher: Wiley
Date: 11-06-2019
Electrochemical reduction of CO2on defect-rich Bi derived from Bi2S3with enhanced formate selectivity
Publisher: Royal Society of Chemistry (RSC)
Date: 2018
DOI: 10.1039/C8TA00023A
Abstract: An urchin-like sulphide-derived bismuth electrocatalyst was synthesised for CO 2 reduction and a maximum of 84.0% faradaic efficiency for formate formation was achieved. The origin of the activity of the sulphide-derived bismuth catalyst was explored and its defect-rich structure was responsible for the high formate selectivity.
Recent advances and future perspectives for automated parameterisation, Bayesian inference and machine learning in voltammetry
Publisher: Royal Society of Chemistry (RSC)
Date: 2021
DOI: 10.1039/D0CC07549C
Abstract: Advanced data analysis tools such as mathematical optimisation, Bayesian inference and machine learning have the capability to revolutionise the field of quantitative voltammetry.
Bioinspired Electrocatalytic CO2 Reduction by Bovine Serum Albumin‐Capped Silver Nanoclusters Mediated by [α‐SiW12O40]4−
Publisher: Wiley
Date: 10-12-2015
Abstract: Silver nanoclusters capped with bovine serum albumin (AgNC@BSA) were synthesized and applied for the electrocatalytic reduction of CO2 . Inspired by the fact that many enzymes function only in the presence of coenzymes/cofactors that transfer electrons rotons or other groups, an electron transfer mediator was introduced to facilitate the electrical communication between the electrode and the strongly protected catalyst. The AgNC@BSA catalyst mediated by [α-SiW12 O40](4-) anions showed high electrocatalytic activity for CO2 reduction, which was not observed with either component on its own, in dimethylformamide containing 1 % (v/v) water. CO was the major product with excellent faradaic efficiency (>75 %). The onset potential for this catalytic CO2 reduction process is about 400 mV more positive than that found at a bulk silver electrode. This mediator-enhanced catalysis concept provides a general approach to investigate the electrocatalytic activities of nanoclusters, which remain largely unexplored.
A unique proton coupled electron transfer pathway for electrochemical reduction of acetophenone in the ionic liquid [BMIM][BF(4)] under a carbon dioxide atmosphere
Publisher: Royal Society of Chemistry (RSC)
Date: 2011
DOI: 10.1039/C1GC15929A
Discrimination and Evaluation of the Effects of Uncompensated Resistance and Slow Electrode Kinetics from the Higher Harmonic Components of a Fourier Transformed Large-Amplitude Alternating Current Vo
Publisher: American Chemical Society (ACS)
Date: 09-02-2007
DOI: 10.1021/AC061859N
Abstract: The influence of uncompensated resistance (also called the IRu effect, where I is current and Ru is uncompensated resistance) and slow electrode kinetics have been assessed for the dc and first five ac harmonics derived from Fourier transformed large- litude ac voltammetry. Resistance and rate constant conditions emphasized correspond to those where separation of effects attributable to either parameter is essentially impossible under conditions of dc cyclic voltammetry. Results derived from simulations and experiments demonstrate that it is relatively easy to discriminate and quantify contributions from these two effects over a wide range of values using the fourth and fifth harmonic ac components derived from single large- litude ac voltammetric measurement. Furthermore, these ac components also are essentially devoid of background charging current. Concepts developed initially from simulations are confirmed by experimental studies on the following: (a) the oxidation of ferrocene, in moderately resistive CH3CN and highly resistive CH2Cl2 (represents ex les of IRu effect on a reversible electron-transfer process) (b) the reduction of a low 0.2 mM concentration of [Fe(CN)6]3- in the highly conductive 3 M KCl electrolyte media (case of slow kinetics with negligible IRu effect) (c) and reduction of a high 10 mM concentration of [Fe(CN)6]3- in less conductive aqueous 0.5 M KCl electrolyte media (ex le where the simultaneous effects of both IRu and slow kinetics need to be resolved).
Kinetics of IrCl62- Ion Transfer across the Water/1,2-Dichloroethane Interface and the Effect of a Phospholipid Monolayer
Publisher: American Chemical Society (ACS)
Date: 21-02-2002
DOI: 10.1021/LA011511H
Remarkable sensitivity of the electrochemical reduction of benzophenone to proton availability in ionic liquids
Publisher: Wiley
Date: 15-03-2012
Abstract: The reduction of benzophenone was investigated in five different ionic liquids by using transient cyclic voltammetry, near steady-state voltammetry, and numerical simulation. Two reversible, well-resolved one-electron-reduction processes were observed in dry (≤20 ppm water, ca. 1 mM)) 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide ([Bmpyrd][NTf(2)]) and 1-butyl-1-methylpiperidinium bis(trifluoromethylsulfonyl)imide ([Bmpipd][NTf(2)]), which did not contain any readily available proton source. Upon addition of water, the second process became chemically irreversible and shifted to a more positive potential by approximately 600 mV moreover, the two reduction processes merged into a single two-electron proton-coupled process when about 0.6 M H(2)O was present. This large dependence of potential on water content, which was not observed in molecular solvents (electrolyte), was explained by a reaction mechanism that incorporated protonation and hydrogen-bonding interactions of the benzophenone dianion with as many as seven water molecules. In the three imidazolium-based ionic liquids used herein, the first benzophenone-reduction process was again reversible, whilst the second reduction process became chemically irreversible owing to the availability of the C2-H imidazolium protons in these ionic liquids. The reversible potentials for benzophenone reduction were remarkably independent of the identity of the ionic liquids, thereby implying either weak interactions with the ionic liquids or relatively insignificant differences in the levels of ion-pairing. Thus, the magnitude of the separation of the potentials of the reversible first and irreversible second reduction processes mainly reflected the proton availability from either the ionic liquid itself or from adventitious water. Consequently, voltammetric reduction of benzophenone provides a sensitive tool for the determination of proton availability in ionic liquids.
Potential Dependence of Electron-Transfer Rates at the Interface between Two Immiscible Electrolyte Solutions: Reduction of 7,7,8,8-Tetracyanoquinodimethane in 1,2-Dichloroethane by Aqueous Ferrocyan
Publisher: American Chemical Society (ACS)
Date: 31-12-1999
DOI: 10.1021/JP993374R
Aerosol-assisted chemical vapour deposition of highly efficient mixed anatase-rutile TiO2 for photoelectrochemical water splitting
Publisher: Royal Society of Chemistry (RSC)
Date: 2023
DOI: 10.1039/D3MA00364G
Abstract: New and bespoke precursors have been used to fabricate mixed anatase-rutile TiO 2 with exceptional photoelectrochemical performance towards water splitting.
Synthesis, characterization and morphology of reduced graphene oxide–metal–TCNQ nanocomposites
Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C3TC32178A
Effect of phospholipids on the kinetics of dioxygen transfer across a 1,2-dichloroethane/water interface
Publisher: Royal Society of Chemistry (RSC)
Date: 04-12-2001
DOI: 10.1039/B106753B
Identification of a new substrate effect that enhances the electrocatalytic activity of dendritic tin in CO2 reduction
Publisher: Royal Society of Chemistry (RSC)
Date: 2018
DOI: 10.1039/C7CP07723H
Abstract: A Sn electrocatalyst for CO 2 reduction to formate with enhanced selectivity has been developed based on a new substrate effect.
Size Controllable Metal Nanoparticles Anchored on Nitrogen Doped Carbon for Electrocatalytic Energy Conversion
Publisher: Wiley
Date: 04-02-2019
Direct Electrodeposition of Graphene-Gold Nanocomposite Films for Ultrasensitive Voltammetric Determination of Mercury(II)
Publisher: Wiley
Date: 25-09-2014
Probing Electrode Heterogeneity using Fourier-Transformed Alternating Current Voltammetry: Protocol Development
Publisher: Elsevier BV
Date: 06-2017
Controllable Synthesis of Few-Layer Bismuth Subcarbonate by Electrochemical Exfoliation for Enhanced CO2 Reduction Performance
Publisher: Wiley
Date: 03-09-2018
Abstract: Two‐dimensional (2D) engineering of materials has been recently explored to enhance the performance of electrocatalysts by reducing their dimensionality and introducing more catalytically active ones. In this work, controllable synthesis of few‐layer bismuth subcarbonate nanosheets has been achieved via an electrochemical exfoliation method. These nanosheets catalyse CO 2 reduction to formate with high faradaic efficiency and high current density at a low overpotential owing to the 2D structure and co‐existence of bismuth subcarbonate and bismuth metal under catalytic turnover conditions. Two underlying fast electron transfer processes revealed by Fourier‐transformed alternating current voltammetry (FTacV) are attributed to CO 2 reduction at bismuth subcarbonate and bismuth metal. FTacV results also suggest that protonation of CO 2 .− is the rate determining step for bismuth catalysed CO 2 reduction.
Dual-Frequency Alternating Current Designer Waveform for Reliable Voltammetric Determination of Electrode Kinetics Approaching the Reversible Limit
Publisher: American Chemical Society (ACS)
Date: 02-02-2016
DOI: 10.1021/ACS.ANALCHEM.5B04354
Abstract: Alternating current (ac) voltammetry provides access to faster electrode kinetics than direct current (dc) methods. However, difficulties in ac and other methods arise when the heterogeneous electron-transfer rate constant (k(0)) approaches the reversible limit, because the voltammetric characteristics become insensitive to electrode kinetics. Thus, in this near-reversible regime, even small uncertainties associated with bulk concentration (C), diffusion coefficient (D), electrode area (A), and uncompensated resistance (Ru) can lead to significant systematic error in the determination of k(0). In this study, we have introduced a kinetically sensitive dual-frequency designer waveform into the Fourier-transformed large- litude alternating current (FTAC) voltammetric method that is made up of two sine waves having the same litude but with different frequencies (e.g., 37 and 615 Hz) superimposed onto a dc r to quantify the close-to-reversible Fc(0/+) process (Fc = ferrocene) in two nonhaloaluminate ionic liquids. The concept is that from a single experiment the lower-frequency data set, collected on a time scale where the target process is reversible, can be used as an internal reference to calibrate A, D, C, and Ru. These calibrated values are then used to calculate k(0) from analysis of the harmonics of the higher-frequency data set, where the target process is quasi-reversible. With this approach, k(0) values of 0.28 and 0.11 cm·s(-1) have been obtained at a 50 μm diameter platinum microdisk electrode for the close-to-diffusion-controlled Fc(0/+) process in two ionic liquids, 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide and 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, respectively.
Theoretical Assessment of Binding and Mass‐Transport Effects in Electrochemical Affinity Biosensors That Utilize Nanoparticle Labels for Signal Amplification
Publisher: Wiley
Date: 27-09-2012
Abstract: This paper presents a theoretical study of electrochemical affinity biosensors for the detection of DNA rotein that utilize nanoparticle labels for signal lification. This study analyzes the effects of binding and mass transport of the analytes on biosensor performance by using numerical simulations. Four cases were considered: 1) nanoparticles used to increase the loading of an electroactive species, or used as catalysts under pseudo-first-order conditions 2) nanoparticles used as ultramicroelectrode arrays for the electrolysis of large concentrations of substrate 3) nanoparticles used as seeds to deposit electrochemically detectable species and 4) nanoparticles used to mediate the deposition of electrocatalysts. By using nanoparticle labels, high sensitivity is possible under all conditions considered. However, theoretical findings suggested that nonspecific adsorption could be more problematic in cases 2-4 due to the mismatch between the chemistry of surface binding and the principle of signal lification that originates from the effect of mass transport. Under these conditions, any given signal would plateau at a much lower analyte concentration, well before the analyte binding had actually reached a plateau. Views on possible solutions to the above limitations are also presented.
Mass Transport Studies and Hydrogen Evolution at a Platinum Electrode Using Bis(trifluoromethanesulfonyl)imide as the Proton Source in Ionic Liquids and Conventional Solvents
Publisher: American Chemical Society (ACS)
Date: 03-12-2014
DOI: 10.1021/JP510754M
Electrochemical transformation of biomass-derived oxygenates
Publisher: Springer Science and Business Media LLC
Date: 03-02-2023
Electrooxidation of Ethanol and Methanol Using the Molecular Catalyst [{Ru4O4(OH)2(H2O)4}(γ-SiW10O36)2]10–<
Publisher: American Chemical Society (ACS)
Date: 22-02-2016
DOI: 10.1021/JACS.5B11408
Abstract: Highly efficient electrocatalytic oxidation of ethanol and methanol has been achieved using the ruthenium-containing polyoxometalate molecular catalyst, [{Ru4O4(OH)2(H2O)4}(γ-SiW10O36)2](10-) ([1(γ-SiW10O36)2](10-)). Voltammetric studies with dissolved and surface-confined forms of [1(γ-SiW10O36)2](10-) suggest that the oxidized forms of 1 can act as active catalysts for alcohol oxidation in both aqueous (over a wide pH range covering acidic, neutral, and alkaline) and alcohol media. Under these conditions, the initial form of 1 also exhibits considerable reactivity, especially in neutral solution containing 1.0 M NaNO3. To identify the oxidation products, preparative scale bulk electrolysis experiments were undertaken. The products detected by NMR, gas chromatography (GC), and GC-mass spectrometry from oxidation of ethanol are 1,1-diethoxyethane and ethyl acetate formed from condensation of acetaldehyde or acetic acid with excess ethanol. Similarly, the oxidation of methanol generates formaldehyde and formic acid which then condense with methanol to form dimethoxymethane and methyl formate, respectively. These results demonstrate that electrocatalytic oxidation of ethanol and methanol occurs via two- and four-electron oxidation processes to yield aldehydes and acids. The total faradaic efficiencies of electrocatalytic oxidation of both alcohols exceed 94%. The numbers of aldehyde and acid products per catalyst were also calculated and compared with the literature reported values. The results suggest that 1 is one of the most active molecular electrocatalysts for methanol and ethanol oxidation.
An integrated instrumental and theoretical approach to quantitative electrode kinetic studies based on large amplitude Fourier transformed a.c. voltammetry: A mini review
Publisher: Elsevier BV
Date: 08-2015
Impact of sp2 Carbon Edge Effects on the Electron-Transfer Kinetics of the Ferrocene/Ferricenium Process at a Boron-Doped Diamond Electrode in an Ionic Liquid
Publisher: American Chemical Society (ACS)
Date: 19-06-2019
Interpreting the results of clinical trials, embracing uncertainty: A Bayesian approach
Publisher: Wiley
Date: 24-10-2020
DOI: 10.1111/AAS.13725
Abstract: Most clinical trials use null hypothesis significance testing with frequentist statistical inference to report P values and confidence intervals for effect estimates. This method leads to a dichotomisation of results as ‘significant’ or ‘non‐significant’. A more nuanced interpretation may often be considered and in particular when the majority of the confidence interval for the effect estimate suggests benefit or harm. In contrast to the frequentist dichotomised approach based on a P value, the application of Bayesian statistics allocates credibility to a continuous spectrum of possibilities and for this reason a Bayesian approach to inference is often warranted as it will incorporate uncertainty when updating our current belief with information from a new trial. The use of Bayesian statistics is introduced in this paper for a hypothetical sepsis trial with worked ex les in the R language for Statistical Computing environment and the open‐source statistical software JASP. It is hoped that this general introduction to Bayesian inference stimulates some interest and confidence among clinicians to consider applying these methods to the interpretation of new evidence for interventions relevant to anaesthesia and intensive care medicine.
Voltammetry of Adhered Microparticles in Contact with Ionic Liquids: Principles and Applications
Publisher: Springer International Publishing
Date: 2015
Two-Dimensional Boron Sheets as Metal-Free Catalysts for Hydrogen Evolution Reaction
Publisher: American Chemical Society (ACS)
Date: 26-07-2018
Proton Diffusion at Phospholipid Assemblies
Publisher: American Chemical Society (ACS)
Date: 16-02-2002
DOI: 10.1021/JA012074W
Abstract: A new scanning electrochemical microscopy proton feedback method has been developed for investigating lateral proton diffusion at phospholipid assemblies: specifically Langmuir monolayers at the water/air interface. In this approach, a base is electrogenerated by the reduction of a weak acid (producing hydrogen) at a "submarine" ultramicroelectrode (UME) placed in the aqueous subphase of a Langmuir trough close to a monolayer. The electrogenerated base diffuses to and titrates monolayer-bound protons and is converted back to its initial form, so enhancing the current response at the UME. Local deprotonation of the monolayer creates a concentration gradient for lateral proton diffusion. A numerical model has been developed, taking into account the potential-dependent association/dissociation constant of the interfacial acid groups. A comparison is made of monolayers comprising either acidic DL-alpha-phosphatidyl-L-serine, dipalmitoyl (DPPS) or zwitterionic L-alpha-phosphatidylcholine, dipalmitoyl (DPPC) monolayers at a range of surface pressures. It is demonstrated that lateral proton fluxes at DPPS are significant, but the lateral proton diffusion coefficient is lower than in bulk solution. In contrast, lateral proton diffusion cannot be detected at DPPC, suggesting that the acid/base character of the phospholipid is important in determining the magnitude of interfacial proton fluxes.
Thermodynamics, Electrode Kinetics, and Mechanistic Nuances Associated with the Voltammetric Reduction of Dissolved [n-Bu4N]4[PW11O39{Sn(C6
Publisher:
American Chemical Society (ACS)
Date:
31-03-2020
Demonstration of anti-oxidant properties of mustard seed (Brassica juncea) protein isolate in orange juice
Publisher: Elsevier BV
Date: 12-2022
Probing Electrode Heterogeneity Using Fourier-Transformed Alternating Current Voltammetry: Application to a Dual-Electrode Configuration
Publisher: American Chemical Society (ACS)
Date: 13-02-2017
DOI: 10.1021/ACS.ANALCHEM.6B03924
Abstract: Quantitative studies of electron transfer processes at electrode/electrolyte interfaces, originally developed for homogeneous liquid mercury or metallic electrodes, are difficult to adapt to the spatially heterogeneous nanostructured electrode materials that are now commonly used in modern electrochemistry. In this study, the impact of surface heterogeneity on Fourier-transformed alternating current voltammetry (FTACV) has been investigated theoretically under the simplest possible conditions where no overlap of diffusion layers occurs and where numerical simulations based on a 1D diffusion model are sufficient to describe the mass transport problem. Experimental data that meet these requirements can be obtained with the aqueous [Ru(NH
Rhodium-Catalyzed Hydroformylation of Alkenes Using in Situ High-Pressure IR and Polymer Matrix Techniques
Publisher: American Chemical Society (ACS)
Date: 12-03-2003
DOI: 10.1021/OM020854N
Ultrasensitive electrochemical immunosensor employing glucose oxidase catalyzed deposition of gold nanoparticles for signal amplification
Publisher: Elsevier BV
Date: 09-2011
DOI: 10.1016/J.BIOS.2011.06.007
Abstract: This paper describes a novel enzymatic lification strategy for ultrasensitive electrochemical immunosensing. This approach utilizes glucose oxidase for the enzymatic deposition of gold nanoparticles onto an indium tin oxide (ITO) electrode surface using a novel gold developer solution consisting of 20 mM of glucose, 20 mM of NaSCN, 0.5 M of p-benzoquinone (PBQ) and 1 mM of AuCl(4)(-) dissolved in 0.1 M of pH 7.5 phosphate buffer solution. The amount of gold deposited was quantified electrochemically by monitoring the reduction of gold oxide in an aqueous solution of 0.5 M of H(2)SO(4), which was correlated to the amount of antigens in the solution. The effectiveness of this strategy was demonstrated experimentally through the construction of an immunosensor for the detection of mouse IgG using a sandwich immunoassay in a linear dynamic range of 5 pg/ml to 50 ng/ml. A good mean apparent recovery in the range of 88-102% was obtained over the entire linear dynamic range of the sensor response in the serum s les. This suggested that the immunosensor would be useful for the testing of proteins in real clinical s les.
Related Organisations
University Of Warwick
Location: United Kingdom of Great Britain and Northern Ireland
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