simone ciampi

Reduced graphene oxide-silicon interface involving direct Si-O bonding as a conductive and mechanical stable ohmic contact

Publisher: Royal Society of Chemistry (RSC)

Date: 2020

DOI: 10.1039/D0CC02310H

Abstract: Electrochemically reduced graphene oxide, chemically bonded to silicon, lowers the contact resistance to metals and enables a tunable ohmic contact.

The corona of a surface bubble promotes electrochemical reactions

Publisher: Springer Science and Business Media LLC

Date: 10-12-2020

DOI: 10.1038/S41467-020-20186-0

Abstract: The evolution of gaseous products is a feature common to several electrochemical processes, often resulting in bubbles adhering to the electrode’s surface. Adherent bubbles reduce the electrode active area, and are therefore generally treated as electrochemically inert entities. Here, we show that this general assumption does not hold for gas bubbles masking anodes operating in water. By means of imaging electrochemiluminescent systems, and by studying the anisotropy of polymer growth around bubbles, we demonstrate that gas cavities adhering to an electrode surface initiate the oxidation of water-soluble species more effectively than electrode areas free of bubbles. The corona of a bubble accumulates hydroxide anions, unbalanced by cations, a phenomenon which causes the oxidation of hydroxide ions to hydroxyl radicals to occur at potentials at least 0.7 V below redox tabled values. The downhill shift of the hydroxide oxidation at the corona of the bubble is likely to be a general mechanism involved in the initiation of heterogeneous electrochemical reactions in water, and could be harnessed in chemical synthesis.

Sublayer-enhanced atomic sites of single atom catalysts through in situ atomization of metal oxide nanoparticles

Publisher: Royal Society of Chemistry (RSC)

Date: 2022

DOI: 10.1039/D1EE03311E

Abstract: The in situ atomization of carbon supported metal oxide nanoparticles provides a novel strategy to synthesize atomic sites supported on highly graphitized carbon materials with high metal loading and controlled atomic layers.

Covalent Linkages of Molecules and Proteins to Si-H Surfaces Formed by Disulfide Reduction.

Publisher: American Chemical Society (ACS)

Date: 03-12-2020

DOI: 10.1021/ACS.LANGMUIR.0C02391

Irreproducibility in the triboelectric charging of insulators: evidence of a non-monotonic charge versus contact time relationship

Publisher: Royal Society of Chemistry (RSC)

Date: 2020

DOI: 10.1039/D0CP01317J

Abstract: Contact electrification: irreproducibility of triboelectric charging magnitudes. Using Faraday pail measurements we show that a monotonous charging slope holds only left or right of a material-specific charge-peak point.

Mesoporous silicon photonic crystal microparticles: Towards single-cell optical biosensors

Publisher: Royal Society of Chemistry (RSC)

Date: 2011

DOI: 10.1039/C005340F

Microelectrode arrays with active-area geometries defined by spatial light modulation

Publisher: Elsevier BV

Date: 10-2020

DOI: 10.1016/J.ELECTACTA.2020.136849

Electrochemical and Electrostatic Cleavage of Alkoxyamines

Publisher: American Chemical Society (ACS)

Date: 08-01-2018

DOI: 10.1021/JACS.7B11628

Abstract: Alkoxyamines are heat-labile molecules, widely used as an in situ source of nitroxides in polymer and materials sciences. Here we show that the one-electron oxidation of an alkoxyamine leads to a cation radical intermediate that even at room temperature rapidly fragments, releasing a nitroxide and carbocation. Digital simulations of experimental voltammetry and current-time transients suggest that the unimolecular decomposition which yields the "unmasked" nitroxide (TEMPO) is exceedingly rapid and irreversible. High-level quantum computations indicate that the collapse of the alkoxyamine cation radical is likely to yield a neutral nitroxide radical and a secondary phenylethyl cation. However, this fragmentation is predicted to be slow and energetically very unfavorable. To attain qualitative agreement between the experimental kinetics and computational modeling for this fragmentation step, the explicit electrostatic environment within the double layer must be accounted for. Single-molecule break-junction experiments in a scanning tunneling microscope using solvent of low dielectric (STM-BJ technique) corroborate the role played by electrostatic forces on the lysis of the alkoxyamine C-ON bond. This work highlights the electrostatic aspects played by charged species in a chemical step that follows an electrochemical reaction, defines the magnitude of this catalytic effect by looking at an independent electrical technique in non-electrolyte systems (STM-BJ), and suggests a redox on/off switch to guide the cleavage of alkoxyamines at an electrified interface.

Tandem click reactions at acetylene-terminated Si(100) monolayers

Publisher: American Chemical Society (ACS)

Date: 10-05-2011

DOI: 10.1021/LA2013733

Abstract: We demonstrate a simple method for coupling alkynes to alkynes. The method involves tandem azide-alkyne cycloaddition reactions ("click" chemistry) for the immobilization of 1-alkyne species onto an alkyne modified surface in a one-pot procedure. In the case presented, these reactions take place on a nonoxidized Si(100) surface although the approach is general for linking alkynes to alkynes. The applicability of the method in the preparation of electrically well-behaved functionalized surfaces is demonstrated by coupling an alkyne-tagged ferrocene species onto alkyne-terminated Si(100) surfaces. The utility of the approach in biotechnology is shown by constructing a DNA sensing interface by derivatization of the acetylenyl surface with commercially available alkyne-tagged oligonucleotides. Cyclic voltametry, electrochemical impedance spectroscopy, X-ray photoelectron spectroscopy, and X-ray reflectometry are used to characterize the coupling reactions and performance of the final modified surfaces. These data show that this synthetic protocol gives chemically well-defined, electronically well-behaved, and robust (bio)functionalized monolayers on silicon semiconducting surfaces.

Electrochemical behavior of gold colloidal alkyl modified silicon surfaces

Publisher: American Chemical Society (ACS)

Date: 21-10-2009

DOI: 10.1021/AM900427W

Abstract: Herein, we report on the production of nanoelectrode arrays by attaching colloidal gold on silicon-bound mixed self-assembled monolayers of TFA-protected alkenylthiol (C(11)-S-TFA) and undecylenic acid (acid). Effective modification of the surface, tethering of the nanoparticles, and the direct influence of the deprotected alkenylthiol (C(11)-SH) /acid ratio on the number of adherent particles were demonstrated using X-ray photoelectron spectroscopy, electrochemistry, and atomic force microscopy. Cyclic voltammetry showed that the enhancement of electron transfer to the silicon surface by the presence of nanoparticles is influenced by the number of tethered nanoparticles.

Control over Near-Ballistic Electron Transport through Formation of Parallel Pathways in a Single-Molecule Wire

Publisher: American Chemical Society (ACS)

Date: 05-12-2018

DOI: 10.1021/JACS.8B09086

Abstract: This paper reports highly efficient coherent tunneling in single-molecule wires of oligo-ferrocenes with one to three Fc units. The Fc units were directly coupled to the electrodes, i.e., without chemical anchoring groups between the Fc units and the terminal electrodes. We found that a single Fc unit readily interacts with the metal electrodes of an STM break junction (STM = scanning tunneling microscope) and that the zero-voltage bias conductance of an in idual Fc molecular junction increased 5-fold, up to 80% of the conductance quantum G

Different functionalization of the internal and external surfaces in mesoporous materials for biosensing applications using click chemistry

Publisher: American Chemical Society (ACS)

Date: 09-12-2011

DOI: 10.1021/LA102599M

Multi-Responsive Photo- and Chemo-Electrical Single-Molecule Switches

Publisher: American Chemical Society (ACS)

Date: 12-2014

DOI: 10.1021/NL5034599

Abstract: Incorporating molecular switches as the active components in nanoscale electrical devices represents a current challenge in molecular electronics. It demands key requirements that need to be simultaneously addressed including fast responses to external stimuli and stable attachment of the molecules to the electrodes while mimicking the operation of conventional electronic components. Here, we report a single-molecule switching device that responds electrically to optical and chemical stimuli. A light pointer or a chemical signal can rapidly and reversibly induce the isomerization of bifunctional spiropyran derivatives in the bulk reservoir and, consequently, switch the electrical conductivity of the single-molecule device between a low and a high level. The spiropyran derivatives employed are chemically functionalized such that they can respond in fast but practical time scales. The unique multistimuli response and the synthetic versatility to control the switching schemes of this single-molecule device suggest spiropyran derivatives as key candidates for molecular circuitry.

Organic Monolayers on Si(211) for Triboelectricity Generation: Etching Optimization and Relationship between the Electrochemistry and Current Output

Publisher: American Chemical Society (ACS)

Date: 28-09-2022

DOI: 10.1021/ACSANM.2C02006

Spontaneous S-Si bonding of alkanethiols to Si(111)-H: towards Si-molecule-Si circuits.

Publisher: Royal Society of Chemistry (RSC)

Date: 2020

DOI: 10.1039/D0SC01073A

Abstract: Spontaneously formed Si–S bonds enable monolayer and single-molecule Si–molecule–Si circuits.

Harnessing electrostatic catalysis in single molecule, electrochemical and chemical systems: a rapidly growing experimental tool box

Publisher: Royal Society of Chemistry (RSC)

Date: 2018

DOI: 10.1039/C8CS00352A

Abstract: Electrostatic catalysis, once considered theoretical daydreaming, is poised to enter mainstream chemistry, with viable platforms including single molecule experiments, electrified interfaces and pH-switchable charges.

Nanocrystal Inks: Photoelectrochemical Printing of Cu2O Nanocrystals on Silicon with 2D Control on Polyhedral Shapes

Publisher: Wiley

Date: 12-11-2018

DOI: 10.1002/ADFM.201804791

Depth-resolved chemical modification of porous silicon by wavelength-tuned irradiation

Publisher: American Chemical Society (ACS)

Date: 22-10-2012

DOI: 10.1021/LA303649U

Abstract: The ability to impart discrete surface chemistry to the inside and outside of mesoporous silicon is of great importance for a range of biomedical applications, from selective (bio)sensing to tissue-specific drug delivery. Here we present a generic strategy toward achieving depth-resolved functionalization of the external and internal porous surfaces by a simple change in the wavelength of the light being used to promote surface chemical reactions. UV-assisted hydrosilylation, limited by the penetration depth of UV light, is used to decorate the outside of the mesoporous structure with carboxylic acid molecules, and white light illumination triggers the attachment of dialkyne molecules to the inner porous matrix.

The molecular level modification of surfaces: From self-assembled monolayers to complex molecular assemblies

Publisher: Royal Society of Chemistry (RSC)

Date: 2011

DOI: 10.1039/C0CS00139B

Abstract: The modification of surfaces with self-assembled monolayers (SAMs) containing multiple different molecules, or containing molecules with multiple different functional components, or both, has become increasingly popular over the last two decades. This explosion of interest is primarily related to the ability to control the modification of interfaces with something approaching molecular level control and to the ability to characterise the molecular constructs by which the surface is modified. Over this time the level of sophistication of molecular constructs, and the level of knowledge related to how to fabricate molecular constructs on surfaces have advanced enormously. This critical review aims to guide researchers interested in modifying surfaces with a high degree of control to the use of organic layers. Highlighted are some of the issues to consider when working with SAMs, as well as some of the lessons learnt (169 references).

Comparing the reactivity of alkynes and alkenes on silicon 100 surfaces

Publisher: American Chemical Society (ACS)

Date: 09-07-2009

DOI: 10.1021/LA901526E

Functionalization of acetylene-terminated monolayers on Si(100) surfaces: A click chemistry approach

Publisher: American Chemical Society (ACS)

Date: 27-07-2007

DOI: 10.1021/LA701035G

Light-activated electrochemistry without surface-bound redox species

Publisher: Elsevier BV

Date: 10-2017

DOI: 10.1016/J.ELECTACTA.2017.08.127

Effect of Electric Fields on Silicon-Based Monolayers

Publisher: American Chemical Society (ACS)

Date: 27-02-2022

DOI: 10.1021/ACS.LANGMUIR.2C00015

Electrochemistry on Tribocharged Polymers Is Governed by the Stability of Surface Charges Rather than Charging Magnitude

Publisher: American Chemical Society (ACS)

Date: 18-03-2019

DOI: 10.1021/JACS.9B00297

Abstract: Electrically insulating objects gain a net electrical charge when brought in and out of contact. This phenomenon-triboelectricity-involves the flow of charged species, but conclusively establishing their nature has proven extremely difficult. Here, we demonstrate an almost linear relationship between a plastic s le's net negative charge and the amount of solution metal ions discharged to metallic particles with a coefficient of proportionality linked to its electron affinity (stability of anionic fragments). The maximum magnitude of reductive redox work is also material dependent: metallic particles grow to a larger extent over charged dielectrics that yield stable cationic fragments (smaller ionization energy). Importantly, the extent to which the s le can act as electron source greatly exceeds the net charging measured in a Faraday pail/electrometer set up, which brings direct evidence of triboeletricity being a mosaic of positive and negative charges rather than a homogeneous ensemble and defines for the first time their quantitative scope in electrochemistry.

Wet chemical routes to the assembly of organic monolayers on silicon surfaces via the formation of Si-C bonds: Surface preparation, passivation and functionalization

Publisher: Royal Society of Chemistry (RSC)

Date: 2010

DOI: 10.1039/B923890P

Probing the Effect of the Solution Environment around Redox-Active Moieties Using Rigid Anthraquinone Terminated Molecular Rulers

Publisher: American Chemical Society (ACS)

Date: 29-10-2012

DOI: 10.1021/JA307665K

Abstract: Herein, we report the influence of the position and the solution environment around surface-bound redox-active moieties on their redox reaction. The study was made possible by using rigid norbornylogous bridges, which possess anthraquinone (AQ) moieties. An L-shaped norbornylogous bridge (L-NB) and straight-shaped norbornylogous bridge (S-NB) were used to situate AQ moieties at well-defined position and environments above a mixed alkanethiol self-assembled monolayer (SAM) on Au (111) surfaces. Sum frequency generation (SFG) vibrational spectroscopy was employed to evaluate the interaction between the S-NB and L-NB with diluent molecules in the mixed SAMs. The SFG measurements demonstrated that hydrogen-bonding interactions were formed between AQ moieties of L-NB and diluent molecules terminated by hydroxyl group within a suitable separation. The SFG observations provided information about the relative position of the AQ moieties in each SAM, which significantly affects the thermodynamics and the kinetics of the electron transfer on the electrode/solution interface. The rate constant (k(et)) of the electron transfer between the AQ moiety and the gold surface and the apparent formal potential (E(0')) were studied using cyclic voltammetry (CV), alternating current voltammetry (ACV), and electrochemical impedance spectroscopy (EIS). It was found that the k(et) increases and E(0') shifts to more anodic values as the distance between the AQ moiety and the surface of the diluent was increased, for both methyl and hydroxyl terminated diluent. These results are discussed in relation to H-bonding interactions with water surrounding the AQ moieties.

Electrostatic catalysis of a Diels-Alder reaction

Publisher: Springer Science and Business Media LLC

Date: 03-2016

DOI: 10.1038/NATURE16989

Abstract: It is often thought that the ability to control reaction rates with an applied electrical potential gradient is unique to redox systems. However, recent theoretical studies suggest that oriented electric fields could affect the outcomes of a range of chemical reactions, regardless of whether a redox system is involved. This possibility arises because many formally covalent species can be stabilized via minor charge-separated resonance contributors. When an applied electric field is aligned in such a way as to electrostatically stabilize one of these minor forms, the degree of resonance increases, resulting in the overall stabilization of the molecule or transition state. This means that it should be possible to manipulate the kinetics and thermodynamics of non-redox processes using an external electric field, as long as the orientation of the approaching reactants with respect to the field stimulus can be controlled. Here, we provide experimental evidence that the formation of carbon-carbon bonds is accelerated by an electric field. We have designed a surface model system to probe the Diels-Alder reaction, and coupled it with a scanning tunnelling microscopy break-junction approach. This technique, performed at the single-molecule level, is perfectly suited to deliver an electric-field stimulus across approaching reactants. We find a fivefold increase in the frequency of formation of single-molecule junctions, resulting from the reaction that occurs when the electric field is present and aligned so as to favour electron flow from the dienophile to the diene. Our results are qualitatively consistent with those predicted by quantum-chemical calculations in a theoretical model of this system, and herald a new approach to chemical catalysis.

Common Background Signals in Voltammograms of Crystalline Silicon Electrodes are Reversible Silica-Silicon Redox Chemistry at Highly Conductive Surface Sites

Publisher: American Chemical Society (ACS)

Date: 29-12-2021

DOI: 10.1021/JACS.0C10713

Spatiotemporal Control of Electrochemiluminescence Guided by a Visible Light Stimulus

Publisher: Elsevier BV

Date: 07-2020

DOI: 10.1016/J.XCRP.2020.100107

Nanoscale Water Condensation on Click-Functionalized Self-Assembled Monolayers

Publisher: American Chemical Society (ACS)

Date: 04-08-2011

DOI: 10.1021/LA202359C

Abstract: We have examined the nanoscale adsorption of molecular water under ambient conditions onto a series of well-characterized functionalized surfaces produced by Cu(I)-catalyzed alkyne-azide cycloaddition (CuAAC or "click") reactions on alkyne-terminated self-assembled monolayers on silicon. Water contact angle (CA) measurements reveal a range of macroscopic hydrophilicity that does not correlate with the tendency of these surfaces to adsorb water at the molecular level. X-ray reflectometry has been used to follow the kinetics of water adsorption on these "click"-functionalized surfaces, and also shows that dense continuous molecular water layers are formed over 30 h. For ex le, a highly hydrophilic surface, functionalized by an oligo(ethylene glycol) moiety (with a CA = 34°) showed 2.9 Å of adsorbed water after 30 h, while the almost hydrophobic underlying alkyne-terminated monolayer (CA = 84°) showed 5.6 Å of adsorbed water over the same period. While this study highlights the capacity of X-ray reflectometry to study the structure of adsorbed water on these surfaces, it should also serve as a warning for those intending to characterize self-assembled monolayers and functionalized surfaces to avoid contamination by even trace amounts of water vapor. Moreover, contact angle measurements alone cannot be relied upon to predict the likely degree of moisture uptake on such surfaces.

Light-addressable electrochemistry at semiconductor electrodes: redox imaging, mask-free lithography and spatially resolved chemical and biological sensing

Publisher: Royal Society of Chemistry (RSC)

Date: 2019

DOI: 10.1039/C8CS00762D

Abstract: Electrochemical reactions in 2D with one electrical lead and a single-channel potentiostat.

Mechanism of Oxidative Alkoxyamine Cleavage: The Surprising Role of the Solvent and Supporting Electrolyte

Publisher: American Chemical Society (ACS)

Date: 06-04-2019

DOI: 10.1021/ACS.JPCC.9B01832

Electric Field Modulation of Silicon upon Tethering of Highly Charged Nucleic Acids. Capacitive Studies on DNA‐modified Silicon (111)

Publisher: Wiley

Date: 10-2016

DOI: 10.1002/ELAN.201600285

Chemically and Mechanically Controlled Single-Molecule Switches Using Spiropyrans

Publisher: American Chemical Society (ACS)

Date: 16-09-2019

DOI: 10.1021/ACSAMI.9B11044

Abstract: Developing molecular circuits that can function as the active components in electrical devices is an ongoing challenge in molecular electronics. It demands mechanical stability of the single-molecule circuit while simultaneously being responsive to external stimuli mimicking the operation of conventional electronic components. Here, we report single-molecule circuits based on spiropyran derivatives that respond electrically to chemical and mechanical stimuli. The merocyanine that results from the protonation/ring-opening of the spiropyran form showed single-molecule diode characteristics, with an average current rectification ratio of 5 at ±1 V, favoring the orientation where the positively charged end of the molecule is attached to the negative terminal of the circuit. Mechanical pulling of a single spiropyran molecule drives a switch to a more conducting merocyanine state. The mechanical switching is enabled by the strong Au-C covalent bonding between the molecule and the electrodes, which allows the tensile force delivered by the STM piezo to break the molecule at its spiropyran C-O bond.

DNA-Hybridization Detection on Si(100) Surfaces Using Light-Activated Electrochemistry: A Comparative Study between Bovine Serum Albumin and Hexaethylene Glycol as Antifouling Layers

Publisher: American Chemical Society (ACS)

Date: 05-09-2018

DOI: 10.1021/ACS.LANGMUIR.8B02222

Abstract: Light can be used to spatially resolve electrochemical measurements on a semiconductor electrode. This phenomenon has been explored to detect DNA hybridization with light-addressable potentiometric sensors and, more recently, with light-addressable erometric sensors based on organic-monolayer-protected Si(100). Here, a contribution to the field is presented by comparing sensing performances when bovine serum albumin (BSA) and hexaethylene glycol (OEG

Impermeable Graphene Oxide Protects Silicon from Oxidation

Publisher: American Chemical Society (ACS)

Date: 03-08-2021

DOI: 10.1021/ACSAMI.1C06495

Oxidative acetylenic coupling reactions as a surface chemistry tool

Publisher: Royal Society of Chemistry (RSC)

Date: 2011

DOI: 10.1039/C1CP21450K

Distance-dependent electron transfer at passivated electrodes decorated by gold nanoparticles

Publisher: American Chemical Society (ACS)

Date: 20-12-2013

DOI: 10.1021/AC3029486

Abstract: The phenomenon of nanoparticles attached to an electrode passivated by an organic layer allowing efficient electron transfer between redox species in solution and the underlying electrode to be restored has resulted in Chazalviel and Allongue proposing a theory [Chazalviel, J.-N. Allongue, P. J. Am. Chem. Soc.2011, 133, 762-764] to explain this phenomenon. The theory suggests that with electrode-organic layer-nanoparticle constructs, high exchange current densities, compared with when the nanoparticles are absent, results in the rate of electron transfer being independent of the thickness of the organic layer until a threshold thickness is exceeded. Thereafter, the thicker the organic layer, the slower the rate of electron transfer. Herein we provide the first experimental data to support this theory using a single experimental system that can show the transition from thickness independent electron transfer kinetics to distant dependent kinetics. This was achieved using ethylenediamine electrodeposited on a glassy carbon electrode. Different numbers of deposition cycles were applied in order to fabricate different thicknesses of the organic film. The deposited films showed progressively greater blocking abilities toward ruthenium hexamine, as a redox active probe in solution, as the films got thicker. Electron transfer kinetics of nanoparticle-decorated surfaces showed a change from thickness independent to thickness dependent as the organic layer exceeded an average thickness of 20 Å. Electrochemical impedance spectroscopy, cyclic voltammetry, scanning electron microscopy, ellipsometry, and atomic force microscopy were used to characterize the fabricated surfaces.

Electrochemical switching of Si(100) modular assemblies

Publisher: American Chemical Society (ACS)

Date: 22-12-2012

DOI: 10.1021/JA210048X

Abstract: We report on a modular approach for producing well-defined and electrochemically switchable surfaces on Si(100). The switching of these surfaces is shown to change a Si(100) surface from resistant to cell adsorption to promoting cell adhesion. The electrochemical conversion of the modified electrode surface is demonstrated by X-ray photoelectron spectroscopy, X-ray reflectometry, contact angle and cell adhesion studies.

Hydrogen evolution during the electrodeposition of gold nanoparticles at Si(100) photoelectrodes impairs the analysis of current-time transients

Publisher: Elsevier BV

Date: 09-2017

DOI: 10.1016/J.ELECTACTA.2017.06.126

Heterojunctions Based on Amorphous Silicon: A Versatile Surface Engineering Strategy To Tune Peak Position of Redox Monolayers on Photoelectrodes

Publisher: American Chemical Society (ACS)

Date: 12-12-2019

DOI: 10.1021/ACS.JPCC.9B11252

The Position of Solid Carbon Dioxide in the Triboelectric Series

Publisher: CSIRO Publishing

Date: 2019

DOI: 10.1071/CH19239

Abstract: The process of releasing liquid carbon dioxide from a fire extinguisher is accompanied by a strong static charging of the plastic material making up the extinguisher discharge horn. Firefighters often report an electric shock when operating CO2 extinguishers, but the origin of this electrostatic hazard is largely unknown. Here, we begin to investigate this phenomenon, and test the hypothesis of plastic s les being tribocharged on contact with rapidly flowing solid CO2. Using Faraday pail measurements, we show that non-conductive polymers gain a net static charge when brought in and out of contact with dry ice (solid CO2). These measurements of charge sign and magnitude give indirect evidence helping to place solid CO2 for the first time on the triboelectric series. Polydimethylsiloxane (PDMS), polytetrafluoroethylene (PTFE), and polyvinyl chloride (PVC) s les acquire a negative charge when rubbed against dry ice, whereas poly(methyl methacrylate) (PMMA), glass, and nylon surfaces become positively charged. Therefore, we suggest the position of dry ice in the triboelectric series to be close to that of materials with stable cations and unstable anions, possibly locating it between PMMA and PVC.

Terminal Deuterium Atoms Protect Silicon from Oxidation

Publisher: American Chemical Society (ACS)

Date: 28-09-2023

DOI: 10.1021/ACSAMI.3C11598

Light-activated electrochemistry on alkyne-terminated Si(100) surfaces towards solution-based redox probes

Publisher: Elsevier BV

Date: 09-2016

DOI: 10.1016/J.ELECTACTA.2016.07.120

Luciferase‐free Luciferin Electrochemiluminescence

Publisher: Wiley

Date: 25-10-2022

DOI: 10.1002/ANIE.202209670

Abstract: Luciferin is one of Nature's most widespread luminophores, and enzymes that catalyze luciferin luminescence are the basis of successful commercial “glow” assays for gene expression and metabolic ATP formation. Herein we report an electrochemical method to promote firefly's luciferin luminescence in the absence of its natural biocatalyst—luciferase. We have gained experimental and computational insights on the mechanism of the enzyme‐free luciferin electrochemiluminescence, demonstrated its spectral tuning from green to red by means of electrolyte engineering, proven that the colour change does not require, as still debated, a keto/enol isomerization of the light emitter, and gained evidence of the electrostatic‐assisted stabilization of the charge‐transfer excited state by double layer electric fields. Luciferin's electrochemiluminescence, as well as the in situ generation of fluorescent oxyluciferin, are applied towards an optical measurement of diffusion coefficients.

Redox-active monolayers in mesoporous silicon

Publisher: American Chemical Society (ACS)

Date: 20-07-2012

DOI: 10.1021/JP303980X

Nanoscale Silicon Oxide Reduces Electron Transfer Kinetics of Surface-Bound Ferrocene Monolayers on Silicon

Publisher: American Chemical Society (ACS)

Date: 12-12-2021

DOI: 10.1021/ACS.JPCC.1C07788

One-pot synthesis of colloidal silicon quantum dots and surface functionalization via thiol-ene click chemistry

Publisher: Royal Society of Chemistry (RSC)

Date: 2012

DOI: 10.1039/C2CC35954E

Abstract: A solution method for preparing surface functionalized colloidal silicon quantum dots (SiQDs) is presented. SiQDs prepared by this method are reasonably monodispersed and can be further functionalized via thiol-ene click reactions to introduce specific functionalities (i.e. -NH(2), -COOH, -SO(3)(-), alkane, alkene).

Electrostatics and Electrochemistry: Mechanism and Scope of Charge-Transfer Reactions on the Surface of Tribocharged Insulators

Publisher: American Chemical Society (ACS)

Date: 18-02-2021

DOI: 10.1021/JACS.0C11006

A novel route to copper(ii) detection using 'click' chemistry-induced aggregation of gold nanoparticles

Publisher: Royal Society of Chemistry (RSC)

Date: 2012

DOI: 10.1039/C1AN15693D

Abstract: A simple colorimetric method for the detection of copper ions in water is described. This method is based on the 'click' copper(I)-catalyzed azide-alkyne cycloaddition reaction and its use in promoting the aggregation of azide-tagged gold nanoparticles by a dialkyne cross-linker is described. Nanoparticle cross-linking, evidenced as a colour change, is used for the detection of copper ions. The lowest detected concentration by the naked eye was 1.8 μM, with the response linear with log(concentration) between 1.8-200 μM. The selectivity relative to other potentially interfering ions was evaluated.

Spontaneous Formation of Diazonium Salts Thin Films on Silicon Electrodes

Publisher: The Electrochemical Society

Date: 09-2019

DOI: 10.1149/MA2019-02/46/2126

Abstract: Future of electronics will require using single molecule as the active component in electric circuitry. In that vein our group and others have developed single molecule switches 1,2 , single molecular diodes 3 , single molecular resistors and transistors 4 . All these previous studies utilized alkynes, amines, thiols as anchoring groups to metals (mostly on gold (Au)). Despite the popularity of the S-Au linkers, they are mechanically unstable and their contact resistance is variable which complicates device fabrication. To realize molecular electronics devices a change towards more robust contacts is needed. In this study, we show that molecular contacts of o -Dianisidine bis(diazotized) zinc double salt (bis diazo) on silicon (Si) can be made electrochemically and also spontaneously without the need of external electric field (Figure 1a) and can be potentially extended to other types of electrodes. The thin films were characterized electrochemically by spontaneously attaching ferreocene to the distal end of the bis diazo molecule and by using X-ray Photoelectron Spectroscopy (XPS), X-ray Reflectometry (XRR), Atomic Force Microscopy (AFM). Furthermore, electrochemical reduction of bis diazo molecule on different crystalline faces of Si were studied (Figure 1b). We found that Si reduction wave occurs at more positive potential then that observed for Si . To confirm these assignments we have created Si pyramids on Si surface by anisotropic etching in 20% KOH solution. By doing so, we have created a mixed /100 surface that can probe in-situ the difference in the electrochemical reduction between the two crystal faces (Figure 1 c). These types of diazonium salts could be used as molecular diodes, devices since they can spontaneously attach to both gold and silicon. References N. Darwish, M. N. Paddon-Row and J. J. Gooding, Acc. Chem. Res. , 47 , 385 (2013). N. Darwish, A. C. Aragonès, T. Darwish, S. Ci i and I. Díez-Pérez, Nano Lett. , 14 , 7064 (2014). A. C. Aragonès, N. Darwish, S. Ci i, F. Sanz, J. J. Gooding and I. Diéz-Pérez, Nat. Commun. , 8 (2017). M. L. Perrin, E. Burzurí and H. S. J. van der Zant, Chem. Soc. Rev. , 44 , 902 (2015). Figure 1. a) Cyclic voltammogram of a thin film of bis diazo spontaneously grafted on n-type Si (resting in a solution of bis diazo for 2 h on Si surface and then exposed to a solution of ferreocene, scan at 0.2 V/s) b) Cyclic voltammetry of a the reduction of bis diazo on n-type Si (red line (a)) and (black line (b)) at scan rate 0.05 V/ s c) Potential difference in the electrochemical reduction between the two crystal faces on the pyramid surface . Figure 1

Reversible potential-induced structural changes of alkanethiol monolayers on gold surfaces

Publisher: Elsevier BV

Date: 05-2011

DOI: 10.1016/J.ELECOM.2011.01.025

Silicon (100) electrodes resistant to oxidation in aqueous solutions: An unexpected benefit of surface acetylene moieties

Publisher: American Chemical Society (ACS)

Date: 20-10-2016

DOI: 10.1021/LA803710D

Static Electrification of Plastics under Friction: The Position of Engineering‐Grade Polyethylene Terephthalate in the Triboelectric Series

Publisher: Wiley

Date: 13-12-2020

DOI: 10.1002/ADEM.201901201

Separating Convective from Diffusive Mass Transport Mechanisms in Ionic Liquids by Redox Pro-fluorescence Microscopy

Publisher: American Chemical Society (ACS)

Date: 20-06-2023

DOI: 10.1021/ACS.ANALCHEM.3C00168

Electrochemical microscopy based on spatial light modulators: A projection system to spatially address Electrochemical reactions at semiconductors

Publisher: The Electrochemical Society

Date: 30-12-2018

DOI: 10.1149/2.0111804JES

Luciferase‐free Luciferin Electrochemiluminescence

Publisher: Wiley

Date: 25-10-2022

DOI: 10.1002/ANGE.202209670

Abstract: Luciferin is one of Nature's most widespread luminophores, and enzymes that catalyze luciferin luminescence are the basis of successful commercial “glow” assays for gene expression and metabolic ATP formation. Herein we report an electrochemical method to promote firefly's luciferin luminescence in the absence of its natural biocatalyst—luciferase. We have gained experimental and computational insights on the mechanism of the enzyme‐free luciferin electrochemiluminescence, demonstrated its spectral tuning from green to red by means of electrolyte engineering, proven that the colour change does not require, as still debated, a keto/enol isomerization of the light emitter, and gained evidence of the electrostatic‐assisted stabilization of the charge‐transfer excited state by double layer electric fields. Luciferin's electrochemiluminescence, as well as the in situ generation of fluorescent oxyluciferin, are applied towards an optical measurement of diffusion coefficients.

Cover Picture: Luciferase‐free Luciferin Electrochemiluminescence (Angew. Chem. Int. Ed. 46/2022)

Publisher: Wiley

Date: 27-10-2022

DOI: 10.1002/ANIE.202215120

The spontaneous formation of single-molecule junctions via terminal alkynes

Publisher: IOP Publishing

Date: 28-08-2015

DOI: 10.1088/0957-4484/26/38/381001

Abstract: Herein, we report the spontaneous formation of single-molecule junctions via terminal alkyne contact groups. Self-assembled monolayers that form spontaneously from diluted solutions of 1, 4-diethynylbenzene (DEB) were used to build single-molecule contacts and assessed using the scanning tunneling microscopy-break junction technique (STM-BJ). The STM-BJ technique in both its dynamic and static approaches was used to characterize the lifetime (stability) and the conductivity of a single-DEB wire. It is demonstrated that single-molecule junctions form spontaneously with terminal alkynes and require no electrochemical control or chemical deprotonation. The alkyne anchoring group was compared against typical contact groups exploited in single-molecule studies, i.e. amine (benzenediamine) and thiol (benzendithiol) contact groups. The alkyne contact showed a conductance magnitude comparable to that observed with amine and thiol groups. The lifetime of the junctions formed from alkynes were only slightly less than that of thiols and greater than that observed for amines. These findings are important as (a) they extend the repertoire of chemical contacts used in single-molecule measurements to 1-alkynes, which are synthetically accessible and stable and (b) alkynes have a remarkable affinity toward silicon surfaces, hence opening the door for the study of single-molecule transport on a semiconducting electronic platform.

Single-Electrode Electrochemistry: Chemically Engineering Surface Adhesion and Hardness to Maximize Redox Work Extracted from Tribocharged Silicon

Publisher: American Chemical Society (ACS)

Date: 28-10-2019

DOI: 10.1021/ACSANM.9B01726

Non-Ideal Cyclic Voltammetry of Redox Monolayers on Silicon Electrodes: Peak Splitting is Caused by Heterogeneous Photocurrents and Not by Molecular Disorder

Publisher: American Chemical Society (ACS)

Date: 06-01-2022

DOI: 10.1021/ACS.LANGMUIR.1C02723

Abstract: Over the last three decades, research on redox-active monolayers has consolidated their importance as advanced functional material. For widespread monolayer systems, such as alkanethiols on gold, non-ideal multiple peaks in cyclic voltammetry are generally taken as indication of heterogeneous intermolecular interactions─namely, disorder in the monolayer. Our findings show that, contrary to metals, peak multiplicity of silicon photoelectrodes is not diagnostic of heterogeneous intermolecular microenvironments but is more likely caused by photocurrent being heterogeneous across the monolayer. This work is an important step toward understanding the cause of electrochemical non-idealities in semiconductor electrodes so that these can be prevented and the redox behavior of molecular monolayers, as photocatalytic systems, can be optimized.

Antifouling behaviour of silicon surfaces modified with self-assembled monolayers containing both ethylene glycol and charged moieties

Publisher: Elsevier BV

Date: 08-2010

DOI: 10.1016/J.SUSC.2010.04.025

Light-Activated Electrochemistry for the Two-Dimensional Interrogation of Electroactive Regions on a Monolithic Surface with Dramatically Improved Spatial Resolution

Publisher: American Chemical Society (ACS)

Date: 09-06-2016

DOI: 10.1021/ACS.JPCC.6B02289

Electrochemistry on Tribocharged Polymers

Publisher: The Electrochemical Society

Date: 09-2019

DOI: 10.1149/MA2019-02/54/2415

Abstract: Static electrification of insulators is a familiar topic: hair attracted by a party balloon or ink or laser printers transferred to a toner 1 . Contact electrification develops on the surface of insulators which are brought in and out of. Statically charged surfaces has been known to mediate redox work, but the scope in electrochemistry of charged dielectrics remains poorly understood. In 2008, Liu and Bard demonstrated that metal ions can be reduced to elemental metal on a charged polytetrafluoroethylene surface and they proposed that charge carries are electrons 2 . However, in 2011, Bartosz A. Grzybowski demonstrated a random “mosaic” of each polymer surface after contact and separated, suggesting that polymer fragments are responsible of the electrification process 3 . Here we report that the magnitude of electrochemical work on electrostatically-charged polydimethylsiloxane (PDMS), polytetrafluoroethylene (PTFE) and polyvinyl chloride (PVC) s les is material-dependent. We show that the magnitude of redox work mediated by a charge insulator is governed by a trade-off between its ionization energy (IE) and electron affinity (EA) 4 . Using XPS, AFM and TEM we have quantified metal deposition on electrostatically-charged PDMS, PTFE and PVC s les. Quantum chemical methods are used to show that anions are the effector of the redox work and polymer, with plastics of the largest negative value of EA (making negative charges unstable) but that at the same time it will ionize into cationic fragments with relative ease, leads to surfaces able to mediate redox work to the largest extent. This work extends our understanding of the molecular nature of static electricity and may find applications in single-electrode electrochemistry and in the study of electrostatic catalysis on chemical reactivity. References Childress, C. O. Kabell, L. J., Electrostatic Printing System. US Patent No. 3,081,698, 163: 1963. Liu, C.-Y. Bard, A. J., Electrostatic Electrochemistry at Insulators. Nat. Mater. 2008, 7 (6), 505–509. Baytekin, H. Patashinski, A. Branicki, M. Baytekin, B. Soh, S. Grzybowski, B. A., The Mosaic of Surface Charge in Contact Electrification. Science 2011, 333 (6040), 308–312. Zhang, J. Rogers, F. Darwish, N. Gonçales, V. R. Vogel, Y. B. Wang, F. Gooding, J. J. Peiris, M. C. Jia, G. Veder, J.-P., Electrochemistry on tribocharged polymers is governed by the stability of surface charges rather than charging magnitude. Journal of the American Chemical Society 2019 . Figure 1

Coupled Thermodynamic and Kinetic Changes in the Electrochemistry of Ferrocenyl Monolayers Induced by Light

Publisher: American Chemical Society (ACS)

Date: 03-2017

DOI: 10.1021/ACS.LANGMUIR.6B04106

Abstract: We report on the light-induced systematic changes to the thermodynamics and kinetics of ferrocene units attached to a n-type silicon(100) photoelectrode. Both the reaction rate and the energetics of the charge transfer are simultaneously affected by changes in the intensity of the incident light. Cyclic voltammetry shows that increases in the intensity of illumination can drive the redox process toward less positive potentials, with a downhill shift in E

A multimodal optical and electrochemical device for monitoring surface reactions: Redox active surfaces in porous silicon Rugate filters

Publisher: Royal Society of Chemistry (RSC)

Date: 2012

DOI: 10.1039/C2CP43461J

Abstract: Herein, mesoporous silicon (PSi) is configured as a single sensing device that has dual readouts as a photonic crystal sensor in a Rugate filter configuration, and as a high surface area porous electrode. The as-prepared PSi is chemically modified to provide it with stability in aqueous media and to allow for the subsequent coupling of chemical species, such as via Cu(I)-catalyzed cycloaddition reactions between 1-alkynes and azides ("click" reactions). The utility of the bimodal capabilities of the PSi sensor for monitoring surface coupling procedures is demonstrated by the covalent coupling of a ferrocene derivative, as well as by demonstrating ligand-exchange reactions (LER) at the PSi surface. Both types of reactions were monitored through optical reflectivity measurements, as well as electrochemically via the oxidation/reduction of the surface tethered redox species.

Facet-resolved electrochemistry: From single particles to macroscopic crystals

Publisher: Elsevier BV

Date: 10-2022

DOI: 10.1016/J.COELEC.2022.101085

Absence of a Relationship between Surface Conductivity and Electrochemical Rates: Redox-Active Monolayers on Si(211), Si(111), and Si(110)

Publisher: American Chemical Society (ACS)

Date: 12-08-2021

DOI: 10.1021/ACS.JPCC.1C05023

Photolithographic strategy for patterning preformed, chemically modified, porous silicon photonic crystal using click chemistry

Publisher: American Chemical Society (ACS)

Date: 03-07-2013

DOI: 10.1021/AM4006012

Abstract: Porous silicon (PSi) is an ideal platform for label-free biosensing, and the development of porous silicon patterning will open a pathway to the development of highly parallel PSi biochips for detecting multiple analytes. The optical response of PSi photonic crystal is determined by the changes in the effective bulk refractive index resulting from reactions/events occurring within the internal pore space. Therefore, introducing precise chemical functionalities in the pores of PSi is essential to ensure device selectivity. Here we describe the fabrication of PSi patterns that possess discrete chemical functionalities that are restricted to precise locations. The key difference to previous patterning protocols for PSi is that the entire porous material is first modified with a self-assembled monolayer of a α,ω-diyne adsorbate prior to patterning using a microfabricated titanium mask. The distal alkyne moieties in the monolayer are then amenable to further selective modification by the archetypal "click" reaction, the copper catalyzed alkyne-azide cycloaddition (CuAAC), using the titanium mask as a resist. This type of patterning is suitable for further immobilization of biological recognition elements, and presents a new platform for highly parallel PSi biosensor for multiple detections.

Memristor Arrays Formed by Reversible Formation and Breakdown of Nanoscale Silica Layers on Si–H Surfaces

Publisher: American Chemical Society (ACS)

Date: 19-04-2022

DOI: 10.1021/ACSANM.2C00663

Nanoscale condensation of water on self-assembled monolayers

Publisher: Royal Society of Chemistry (RSC)

Date: 2011

DOI: 10.1039/C1SM05096F

Antibody modified porous silicon microparticles for the selective capture of cells

Publisher: American Chemical Society (ACS)

Date: 10-06-2014

DOI: 10.1021/BC500144U

Abstract: Herein, the ability of porous silicon (PSi) particles for selectively binding to specific cells is investigated. PSi microparticles with a high reflectance band in the reflectivity profile are fabricated, and subsequently passivated and modified with antibodies via the Cu(I)-catalyzed alkyne-azide cycloaddition reaction and succimidyl activation. To demonstrate the ability of the antibody-modified PSi particles to selectively bind to one cell type over others, HeLa cells were transfected with surface epitopes fused to fluorescent proteins. The antibody-functionalized PSi particles showed good selectivity for the corresponding surface protein on HeLa cells, with no significant cross-reactivity. The results are important for the application of PSi particles in cell sensing and drug delivery.

Using an Electrical Potential to Reversibly Switch Surfaces between Two States for Dynamically Controlling Cell Adhesion

Publisher: Wiley

Date: 22-06-2012

DOI: 10.1002/ANIE.201202118

Abstract: Smart surfaces presenting both antifouling molecules with a charged functional group at their distal end, and molecules that are terminated by RGD peptides for cell adhesion, were fabricated and characterized (see picture). By applying potentials of +300 or -300 mV, the surfaces could be dynamically switched to make the peptide accessible or inaccessible to cells.

Studies on the effect of solvents on self-assembled monolayers formed from organophosphonic acids on indium tin oxide

Publisher: American Chemical Society (ACS)

Date: 07-06-2012

DOI: 10.1021/LA3010129

Abstract: The preparation of self-assembled monolayers (SAMs) of organophosphonic acids on indium tin oxide (ITO) surfaces from different solvents (triethylamine, ethyl ether, tetrahydofuran (THF), pyridine, acetone, methanol, acetonitrile, dimethyl sulfoxide (DMSO), or water) has been performed with some significant differences observed. Cyclic voltammetry (CV), X-ray photoelectron spectroscopy (XPS), scanning tunneling microscopy (STM), and contact angle measurement demonstrated that the quality of SAMs depends critically on the choice of solvents. Higher density, more stable monolayers were formed from solvents with low dielectric constants and weak interactions with the ITO. It was concluded low dielectric solvents that were inert to the ITO gave monolayers that were more stable with a higher density of surface bound molecules because higher dielectric constant solvents and solvents that coordinate with the surface disrupted SAM formation.

Reproducible flaws unveil electrostatic aspects of semiconductor electrochemistry

Publisher: Springer Science and Business Media LLC

Date: 12-12-2017

DOI: 10.1038/S41467-017-02091-1

Abstract: Predicting or manipulating charge-transfer at semiconductor interfaces, from molecular electronics to energy conversion, relies on knowledge generated from a kinetic analysis of the electrode process, as provided by cyclic voltammetry. Scientists and engineers encountering non-ideal shapes and positions in voltammograms are inclined to reject these as flaws. Here we show that non-idealities of redox probes confined at silicon electrodes, namely full width at half maximum .6 mV and anti-thermodynamic inverted peak positions, can be reproduced and are not flawed data. These are the manifestation of electrostatic interactions between dynamic molecular charges and the semiconductor’s space-charge barrier. We highlight the interplay between dynamic charges and semiconductor by developing a model to decouple effects on barrier from changes to activities of surface-bound molecules. These findings have immediate general implications for a correct kinetic analysis of charge-transfer at semiconductors as well as aiding the study of electrostatics on chemical reactivity.

Metal–Single-Molecule–Semiconductor Junctions Formed by a Radical Reaction Bridging Gold and Silicon Electrodes

Publisher: American Chemical Society (ACS)

Date: 27-08-2019

DOI: 10.1021/JACS.9B07125

Abstract: Here we report molecular films terminated with diazonium salts moieties at both ends which enables single-molecule contacts between gold and silicon electrodes at open circuit via a radical reaction. We show that the kinetics of film grafting is crystal-facet dependent, being more favorable on ⟨111⟩ than on ⟨100⟩, a finding that adds control over surface chemistry during the device fabrication. The impact of this spontaneous chemistry in single-molecule electronics is demonstrated using STM-break junction approaches by forming metal-single-molecule-semiconductor junctions between silicon and gold source and drain, electrodes. Au-C and Si-C molecule-electrode contacts result in single-molecule wires that are mechanically stable, with an average lifetime at room temperature of 1.1 s, which is 30-400% higher than that reported for conventional molecular junctions formed between gold electrodes using thiol and amine contact groups. The high stability enabled measuring current-voltage properties during the lifetime of the molecular junction. We show that current rectification, which is intrinsic to metal-semiconductor junctions, can be controlled when a single-molecule bridges the gap in the junction. The system changes from being a current rectifier in the absence of a molecular bridge to an ohmic contact when a single molecule is covalently bonded to both silicon and gold electrodes. This study paves the way for the merging of the fields of single-molecule and silicon electronics.

Experimental Evidence of Long-Lived Electric Fields of Ionic Liquid Bilayers

Publisher: American Chemical Society (ACS)

Date: 16-10-2021

DOI: 10.1021/JACS.1C06385

Abstract: Herein we demonstrate that ionic liquids can form long-lived double layers, generating electric fields detectable by straightforward open circuit potential (OCP) measurements. In imidazolium-based ionic liquids an external negative voltage pulse leads to an exceedingly stable near-surface dipolar layer, whose field manifests as long-lived (∼1-100 h) discrete plateaus in OCP versus time traces. These plateaus occur within an ionic liquid-specific and sharp potential window, defining a simple experimental method to probe the onset of interfacial ordering phenomena, such as overscreening and crowding. Molecular dynamics modeling reveals that the OCP arises from the alignment of the in idual ion dipoles to the external electric field pulse, with the magnitude of the resulting OCP correlating with the product of the projected dipole moment of the cation and the ratio between the cation diffusion coefficient and its volume. Our findings also reveal that a stable overscreened structure is more likely to form if the interface is first forced through crowding, possibly accounting for the scattered literature data on relaxation kinetics of near-surface structures in ionic liquids.

Grafting of Poly(ethylene glycol) on Click Chemistry Modified Si(100) Surfaces

Publisher: American Chemical Society (ACS)

Date: 21-06-2013

DOI: 10.1021/LA400721C

Abstract: Poly(ethylene glycol) (PEG) is one of the most extensively studied antifouling coatings due to its ability to reduce protein adsorption and improve biocompatibility. Although the use of PEG for antifouling coatings is well established, the stability and density of PEG layers are often inadequate to provide optimum antifouling properties. To improve on these shortcomings, we employed the stepwise construction of PEG layers onto a silicon surface. Acetylene-terminated alkyl monolayers were attached to nonoxidized crystalline silicon surfaces via a one-step hydrosilylation procedure with 1,8-nonadiyne. The acetylene-terminated surfaces were functionalized via a copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction of the surface-bound alkynes with an azide to produce an amine terminated layer. The amine terminated layer was then further conjugated with PEG to produce an antifouling surface. The antifouling surface properties were investigated by testing adsorption of human serum albumin (HSA) and lysozyme (Lys) onto PEG layers from phosphate buffer solutions. Detailed characterization of protein fouling was carried out with X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) combined with principal component analysis (PCA). The results revealed no fouling of albumin onto PEG coatings whereas the smaller protein lysozyme adsorbed to a very low extent.

Erratum: Single-Electrode Electrochemistry: Chemically Engineering Surface Adhesion and Hardness to Maximize Redox Work Extracted from Tribocharged Silicon (ACS Appl. Nano Mater. (2019) 2:11 (7230-7236) DOI: 10.1021/acsanm.9b01726)

Publisher: American Chemical Society (ACS)

Date: 13-12-2019

DOI: 10.1021/ACSANM.9B02390

Optimization of click chemistry of ferrocene derivatives on acetylene-functionalized silicon(100) surfaces

Publisher: Wiley

Date: 07-2008

DOI: 10.1002/ELAN.200804241

Electrochemically Generated Luminescence of Luminol and Luciferin in Ionic Liquids

Publisher: Wiley

Date: 22-12-2022

DOI: 10.1002/CELC.202201033

Abstract: Electrochemiluminescence (ECL) is the generation of light triggered by an electrochemical reaction. ECL has been extensively studied in solvent‐based electrolytes, but there is a lack of data on using electrode reactions to populate an excited‐state light emitter in room temperature ionic liquids (RTILs). This work explores the current response, light intensity (photon counting), and spectral signatures of the cathodic ECL of luminol and firefly's luciferin in imidazolium‐based RTILs. We have demonstrated that the cathodic (superoxide‐triggered) ECL of both luminol and adenylate‐ester of firefly's luciferin is viable in RTILs, explored the effect of water contaminations, and importantly, shown that the ECL signal persists for up to about 700 s after the removal of the external cathodic pulse, which is probably due to the stabilization of superoxide by double‐layer cation‐rich structures. Long‐lived RTIL double‐layer structures and their endogenous fields are detected as stable and discrete open‐circuit potential plateaus.

Click chemistry in mesoporous materials: Functionalization of porous silicon rugate filters

Publisher: American Chemical Society (ACS)

Date: 02-05-2008

DOI: 10.1021/LA800435D

Investigation of the Antifouling Properties of Phenyl Phosphorylcholine-Based Modified Gold Surfaces

Publisher: Wiley

Date: 19-05-2014

DOI: 10.1002/ELAN.201400102

Improving the performances of direct-current triboelectric nanogenerators with surface chemistry

Publisher: Elsevier BV

Date: 10-2022

DOI: 10.1016/J.COCIS.2022.101627

Stability of Chemically Passivated Silicon Electrodes in Aqueous Solutions: Interplay between Bias Voltage and Hydration of the Electrolyte

Publisher: American Chemical Society (ACS)

Date: 22-02-2016

DOI: 10.1021/ACS.JPCC.5B12454

Single-molecule electrical contacts on silicon electrodes under ambient conditions

Publisher: Springer Science and Business Media LLC

Date: 13-04-2017

DOI: 10.1038/NCOMMS15056

Abstract: The ultimate goal in molecular electronics is to use in idual molecules as the active electronic component of a real-world sturdy device. For this concept to become reality, it will require the field of single-molecule electronics to shift towards the semiconducting platform of the current microelectronics industry. Here, we report silicon-based single-molecule contacts that are mechanically and electrically stable under ambient conditions. The single-molecule contacts are prepared on silicon electrodes using the scanning tunnelling microscopy break-junction approach using a top metallic probe. The molecular wires show remarkable current–voltage reproducibility, as compared to an open silicon/nano-gap/metal junction, with current rectification ratios exceeding 4,000 when a low-doped silicon is used. The extension of the single-molecule junction approach to a silicon substrate contributes to the next level of miniaturization of electronic components and it is anticipated it will pave the way to a new class of robust single-molecule circuits.

Target DNA recognition using electrochemical impedance spectroscopy

Publisher: IEEE

Date: 02-2010

DOI: 10.1109/ICONN.2010.6045241

Shape and Charge: Faraday’s Ice Pail Experiment Revisited

Publisher: American Chemical Society (ACS)

Date: 04-2020

DOI: 10.1021/ACSCENTSCI.0C00298

Switching of Current Rectification Ratios within a Single Nanocrystal by Facet-Resolved Electrical Wiring

Publisher: American Chemical Society (ACS)

Date: 06-07-2018

DOI: 10.1021/ACSNANO.8B02934

Abstract: Here we show that within a single polyhedral metal oxide nanoparticle a nanometer-scale lateral or vertical sliding of a small metal top contact ( e. g., <50 nm) leads to a 10-fold change in current rectification ratios. Electron tunneling imaging and constant-force current-potential analysis in atomic force microscopy demonstrate that within an in idual p-n rectifier (a Cu

Harnessing silicon facet-dependent conductivity to enhance the direct-current produced by a sliding Schottky diode triboelectric nanogenerator

Publisher: Elsevier BV

Date: 12-2020

DOI: 10.1016/J.NANOEN.2020.105210

Quantitative Analysis of Cyclic Voltammetry of Redox Monolayers Adsorbed on Semiconductors: Isolating Electrode Kinetics, Lateral Interactions, and Diode Currents

Publisher: American Chemical Society (ACS)

Date: 02-04-2019

DOI: 10.1021/ACS.ANALCHEM.9B00336

Abstract: The design of devices whose functions span from sensing their environments to converting light into electricity or guiding chemical reactivity at surfaces often hinges around a correct and complete understanding of the factors at play when charges are transferred across an electrified solid-liquid interface. For semiconductor electrodes in particular, published values for charge-transfer kinetic constants are scattered. Furthermore, received wisdom suggests slower charge-transfer kinetics for semiconductors than for metal electrodes. We have used cyclic voltammetry of ferrocene-modified silicon photoanodes and photocathodes as the experimental model system and described a systematic analysis to separate charge-transfer kinetics from diode effects and interactions between adsorbed species. Our results suggest that literature values of charge-transfer kinetic constants at semiconductor electrodes are likely to be underestimates of their actual values. This is revealed by experiments and analytical models showing that the description of the potential distribution across the semiconductor-monolayer-electrolyte interface has been largely oversimplified.

The influence of organic-film morphology on the efficient electron transfer at passivated polymer-modified electrodes to which nanoparticles are attached

Publisher: Wiley

Date: 12-04-2013

DOI: 10.1002/CPHC.201300047

Abstract: The impact of polymer-film morphology on the electron-transfer process at electrode/organic insulator/nanomaterial architectures is studied. The experimental data are discussed in the context of the most recent theory modelling the nanoparticle-mediated electron-transfer process at electrode/insulator/nanomaterial architectures proposed by Chazalviel and Allongue [J. Am. Chem. Soc. 2011, 133, 762-764]. A previous report [Anal. Chem. 2013, 85, 1073-1080] by us qualitatively verified the theory and demonstrates a transition from thickness-independent to thickness-dependent electron transfer as the layer thickness exceeds a certain threshold. This follow-up study explores a different polymer, poly(phenylenediamine), and focuses on the effect of the uniformity of organic film on electron transfer at these hybrid structures. Electron-transfer kinetics of modified surfaces, which were assessed using the redox species Ru(NH3)6(3+) in aqueous solution, showed that a thickness-dependent electron-transfer regime is achieved with poly(phenylenediamine). This is attributed to the sufficiently thin films never being fabricated with this polymer. Rather, it is suggested that thin poly(phenylenediamine) layers have a globular structure with poor film homogeneity and pinhole defects.

TEMPO Monolayers on Si(100) Electrodes: Electrostatic Effects by the Electrolyte and Semiconductor Space-Charge on the Electroactivity of a Persistent Radical

Publisher: American Chemical Society (ACS)

Date: 19-07-2016

DOI: 10.1021/JACS.6B04788

Abstract: This work demonstrates the effect of electrostatic interactions on the electroactivity of a persistent organic free radical. This was achieved by chemisorption of molecules of 4-azido-2,2,6,6-tetramethyl-1-piperdinyloxy (4-azido-TEMPO) onto monolayer-modified Si(100) electrodes using a two-step chemical procedure to preserve the open-shell state and hence the electroactivity of the nitroxide radical. Kinetic and thermodynamic parameters for the surface electrochemical reaction are investigated experimentally and analyzed with the aid of electrochemical digital simulations and quantum-chemical calculations of a theoretical model of the tethered TEMPO system. Interactions between the electrolyte anions and the TEMPO grafted on highly doped, i.e., metallic, electrodes can be tuned to predictably manipulate the oxidizing power of surface nitroxide/oxoammonium redox couple, hence showing the practical importance of the electrostatics on the electrolyte side of the radical monolayer. Conversely, for monolayers prepared on the poorly doped electrodes, the electrostatic interactions between the tethered TEMPO units and the semiconductor-side, i.e., space-charge, become dominant and result in drastic kinetic changes to the electroactivity of the radical monolayer as well as electrochemical nonidealities that can be explained as an increase in the self-interaction "a" parameter that leads to the Frumkin isotherm.

Versatile click chemistry Approach to functionalizing silicon quantum dots: Applications toward fluorescent cellular imaging

Publisher: American Chemical Society (ACS)

Date: 28-04-2014

DOI: 10.1021/LA500945F

Abstract: In this study, we describe a solution procedure for the preparation and surface modification of photostable colloidal silicon quantum dots (SiQDs) for imaging of cancer cells. Photoluminescent SiQDs were synthesized by reduction of halogenated silane precursors using a microemulsion process. It was shown that 1,8-nonadiyne molecules could be grafted onto the surface of hydrogen-terminated SiQDs via ultraviolet (UV)-promoted hydrosilylation, demonstrated by Fourier transform infrared spectroscopy (FTIR) measurements. In addition, various azide molecules were coupled onto nonadiyne-functionalized particles, rendering particles dispersible in selected polar and nonpolar solvents. The photoluminescence of functionalized SiQDs was stable against photobleaching and did not vary appreciably within biologically applicable pH and temperature ranges. To demonstrate compatibility with biological systems, water-soluble SiQDs were used for fluorescent imaging of HeLa cells. In addition, the SiQDs were shown to be non-cytotoxic at concentrations up to 240 μg/mL. The results presented herein provide good evidence for the versatility of functionalized SiQDs for fluorescent bioimaging application.

Direct electrochemistry of cytochrome c at modified Si(100) electrodes

Publisher: Wiley

Date: 14-05-2010

DOI: 10.1002/CHEM.200903316

Abstract: This paper demonstrates the direct electron transfer between the heme moiety of horse hearth cytochrome c and a pyridinyl group on self-assembled-monolayer-modified Si(100) electrodes. Self-assembled monolayers (SAMs) containing the putative receptor ligand were prepared by a step-wise procedure using "click" reactions of acetylene-terminated alkyl monolayers and isonicotinic acid azide derivatives. Unoxidized Si(100) electrodes, possessing either isonicotinate or isonicotinamide receptor ligands, were characterized using X-ray photoelectron spectroscopy, contact-angle goniometry, cyclic voltammetry, and electrochemical impedance spectroscopy. The ability of isonicotinic acid terminated layers to coordinatively bind the redox center of cytochrome c was found to be restricted to pyridinyl assemblies with a para-ester linkage present. The protocol detailed here offers an experimentally simple modular approach to producing chemically well-defined SAMs on silicon surfaces for direct electrochemistry of a well-studied model redox protein.

Preparation of thiol-terminated monolayers on silicon(100) surfaces using thioacetyl-protected alkynethiol

Publisher: IEEE

Date: 02-2010

DOI: 10.1109/ICONN.2010.6045195

Silicon (100) surfaces modified by osmium bipyridine complexes

Publisher: IEEE

Date: 02-2010

DOI: 10.1109/ICONN.2010.6045234

Titelbild: Luciferase‐free Luciferin Electrochemiluminescence (Angew. Chem. 46/2022)

Publisher: Wiley

Date: 27-10-2022

DOI: 10.1002/ANGE.202215120

Effect of Chemical Structure on the Electrochemical Cleavage of Alkoxyamines

Publisher: American Chemical Society (ACS)

Date: 13-02-2019

DOI: 10.1021/ACS.JPCC.8B12545

ARC Future Fellowships - Grant ID: FT190100148

Start Date: 05-2020

End Date: 05-2024

Amount: $880,383.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP150103065

Start Date: 2015

End Date: 04-2018

Amount: $419,700.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE230100019

Start Date: 2023

End Date: 12-2023

Amount: $690,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP190100735

Start Date: 2019

End Date: 12-2022

Amount: $310,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE210100126

Start Date: 07-2021

End Date: 07-2022

Amount: $527,638.00

Funder: Australian Research Council

Discovery Early Career Researcher Award - Grant ID: DE160100732

Start Date: 06-2016

End Date: 06-2019

Amount: $359,544.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP220100553

Start Date: 12-2022

End Date: 12-2025

Amount: $300,000.00

Funder: Australian Research Council

Industrial Transformation Training Centres - Grant ID: IC190100034

Start Date: 12-2020

End Date: 12-2025

Amount: $3,574,272.00

Funder: Australian Research Council