ORCID Profile
0000-0002-6565-1723
Current Organisation
Curtin 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)
Nanotechnology | Colloid and Surface Chemistry | Electroanalytical Chemistry | Microelectronics and Integrated Circuits | Electrical and Electronic Engineering | Nanoscale Characterisation | Physical Chemistry not elsewhere classified | Compound Semiconductors | Microelectromechanical Systems (MEMS) | Photonic and electro-optical devices sensors and systems (excl. communications) | Electronics sensors and digital hardware | Electronic device and system performance evaluation testing and simulation | Molecular and Organic Electronics | Nanoelectronics
ANZSRC Socio-Economic Objective (SEO)
Expanding Knowledge in Technology | Environmentally Sustainable Manufacturing not elsewhere classified | Diagnostic Methods | Expanding Knowledge in the Chemical Sciences | Industrial Instruments | Scientific Instruments | Integrated Circuits and Devices | Integrated Systems |
Related Links
Publications
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.
Covalent Linkages of Molecules and Proteins to Si-H Surfaces Formed by Disulfide Reduction.
Publisher: American Chemical Society (ACS)
Date: 03-12-2020
Observation of electrochemically controlled quantum interference in a single anthraquinone-based norbornylogous bridge molecule
Publisher: Wiley
Date: 14-02-2012
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.
Switchable Interfaces: Redox Monolayers on Si(100) by Electrochemical Trapping of Alcohol Nucleophiles
Publisher: MDPI AG
Date: 20-07-2018
Abstract: Organic electrosynthesis is going through its renaissance but its scope in surface science as a tool to introduce specific molecular signatures at an electrode/electrolyte interface is under explored. Here, we have investigated an electrochemical approach to generate in situ surface-tethered and highly-reactive carbocations. We have covalently attached an alkoxyamine derivative on an Si(100) electrode and used an anodic bias stimulus to trigger its fragmentation into a diffusive nitroxide (TEMPO) and a surface-confined carbocation. As a proof-of-principle we have used this reactive intermediate to trap a nucleophile dissolved in the electrolyte. The nucleophile was ferrocenemethanol and its presence and surface concentration after its reaction with the carbocation were assessed by cyclic voltammetry. The work expands the repertoire of available electrosynthetic methods and could in principle lay the foundation for a new form of electrochemical lithography.
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.
Luciferase‐free Luciferin Electrochemiluminescence
Publisher: Wiley
Date: 25-10-2022
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.
Single molecular switches: Electrochemical gating of a single anthraquinone-based norbornylogous bridge molecule
Publisher: American Chemical Society (ACS)
Date: 20-09-2012
DOI: 10.1021/JP3066458
Cover Picture: Luciferase‐free Luciferin Electrochemiluminescence (Angew. Chem. Int. Ed. 46/2022)
Publisher: Wiley
Date: 27-10-2022
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.
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
The rise of self-assembled monolayers for fabricating electrochemical biosensors-an interfacial perspective
Publisher: Wiley
Date: 30-11-2012
Chemical mechanisms, one molecule at a time
Publisher: Springer Science and Business Media LLC
Date: 02-09-2021
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
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.
Surface-bound norbornylogous bridges as molecular rulers for investigating interfacial electrochemistry and as single molecule switches
Publisher: American Chemical Society (ACS)
Date: 28-10-2014
DOI: 10.1021/AR400127G
Abstract: Electron transfer (ET) reactions through molecules attached to surfaces, whether they are through single molecules or ensembles, are the subject of much research in molecular electronics, bioelectronics, and electrochemistry. Therefore, understanding the factors that govern ET is of high importance. The availability of rigid hydrocarbon molecular scaffolds possessing well-defined configurations and lengths that can be systematically varied is crucial to the development of such devices. In this Account, we demonstrate how suitably functionalized norbornylogous (NB) systems can provide important insights into interfacial ET processes and electrical conduction through single molecules. To this end, we created NB bridges with vic-trans-bismethylenethiol groups at one end so they can assemble on gold electrodes and redox species at the distal ends. With these in hand, we then formed mixed self-assembled monolayers (SAMs) containing a small proportion of the NB bridges diluted with alkanethiols. As such, the NB bridges served as molecular rulers for probing the environment above the surface defined by the diluent species. Using this construct, we were able to measure the interfacial potential distribution above the diluent surface, and track how variation in the ionic distribution in the electrical double layer impacts ET kinetics. Using the same construct, but with a redox molecule that remains neutral in both oxidized and reduced states, we could explore the impact of the chemical environment near a surface on ET processes. These results are important, because with conventional surface constructs, ET occurs across this interfacial region. Such knowledge is therefore relevant to the design of molecular systems at surfaces involving ET. With a second family of molecules, we investigated aspects of single-molecule electrical conduction using NB bridges bearing vic-trans-bismethylenethiol groups at both ends of the bridge. This gave us insights into distance-dependent electron transport through single molecules and introduced a method of boosting the conductance of saturated molecules by incorporating aromatic moieties in their backbone. These partially conjugated NB molecules represent a new class of molecular wires with far greater stability than conventional completely conjugated molecular wires. Of particular note was our demonstration of a single molecule switch, using a NB bridge containing an embedded anthraquinone redox group, the switching mechanism being via electrochemically controlled quantum interference.
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.
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
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.
Sliding silicon-based Schottky diodes: Maximizing triboelectricity with surface chemistry
Publisher: Elsevier BV
Date: 03-2022
Ultrasonic Generation of Thiyl Radicals: A General Method of Rapidly Connecting Molecules to a Range of Electrodes for Electrochemical and Molecular Electronics Applications
Publisher: American Chemical Society (ACS)
Date: 23-12-2021
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.
Fabrication of broad area optical nanostructures for high throughput chemical sensing
Publisher: Elsevier BV
Date: 10-2013
Importance of the indium tin oxide substrate on the quality of self-assembled monolayers formed from organophosphonic acids
Publisher: American Chemical Society (ACS)
Date: 11-02-2011
DOI: 10.1021/LA104464W
Surface-bound molecular rulers for probing the electrical double layer
Publisher: American Chemical Society (ACS)
Date: 17-04-2012
DOI: 10.1021/JA301509H
Abstract: Herein, we report the first experimental investigation on the effect of varying the position of redox-active moieties, within the electrical double layer, on the apparent formal potential and on the electron transfer rate constant. This was achieved using a rigid class of molecules, norbornylogous bridges, to place redox species (ferrocene) at a fixed position above the surface of the electrode. Cyclic voltammetry and alternating current voltammetry were used to calculate the apparent formal potential and the electron transfer rate constant for the electron transfer between the ferrocene and the gold electrode. We use the effect of electric field on the apparent formal potential measurement of the surface-bound redox species to calculate the potential drop from the initiation of the electrical double layer to different distances above it. It was found that self-assembled monolayers formed from ω-hydroxyalkanethiol have a potential profile very similar to that described by classical theories for bare metal electrodes. A steep drop in potential in the Stern layer was observed followed by a smaller potential drop in the Gouy-Chapman layer. The electron transfer rate constant was found to decrease as the distance between the ferrocene moiety and the initiation of the double layer is increased. Thus, the electron transfer rate constant appears to be dependent on ion concentration.
Cover Feature: The Surface Potential of Zero Charge Controls the Kinetics of Diazonium Salts Electropolymerization (ChemElectroChem 17/2022)
Publisher: Wiley
Date: 08-2022
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.
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
Building Nanoscale Molecular Wires Exploiting Electrocatalytic Interactions
Publisher: Elsevier BV
Date: 10-2015
Nanocrystal Inks: Photoelectrochemical Printing of Cu2 O Nanocrystals on Silicon with 2D Control on Polyhedral Shapes
Publisher: Wiley
Date: 12-11-2018
Electrochemical grafting of organic films on silica
Publisher: Royal Society of Chemistry (RSC)
Date: 2022
DOI: 10.1039/D2CC03169H
Abstract: Silica becomes conducting in the presence of acid and can be electrochemically functionalized.
CHAPTER 3. Experimentally Harnessing Electric Fields in Chemical Transformations
Publisher: Royal Society of Chemistry
Date: 2021
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.
Fine‐Tuning of Single‐Molecule Conductance by Tweaking Both Electronic Structure and Conformation of Side Substituents
Publisher: Wiley
Date: 02-04-2015
Abstract: Herein, we describe a method to fine-tune the conductivity of single-molecule wires by employing a combination of chemical composition and geometrical modifications of multiple phenyl side groups as conductance modulators embedded along the main axis of the electronic pathway. We have measured the single-molecule conductivity of a novel series of phenyl-substituted carotenoid wires whose conductivity can be tuned with high precision over an order of magnitude range by modulating both the electron-donating character of the phenyl substituent and its dihedral angle. It is demonstrated that the electronic communication between the phenyl side groups and the molecular wire is maximized when the phenyl groups are twisted closer to the plane of the conjugated molecular wire. These findings can be refined to a general technique for precisely tuning the conductivity of molecular wires.
The Effect of Interfacial Design on the Electrochemical Detection of DNA and MicroRNA Using Methylene Blue at Low‐Density DNA Films
Publisher: Wiley
Date: 02-12-2013
Strategies to Achieve Control over the Surface Ratio of Two Different Components on Modified Electrodes Using Aryldiazonium Salts
Publisher: American Chemical Society (ACS)
Date: 03-03-2016
DOI: 10.1021/ACS.LANGMUIR.5B04550
Abstract: Controlling the composition of an interface is very important in tuning the chemical and physical properties of a surface in many applications including biosensors, biomaterials, and chemical catalysis. Frequently, this requires one molecular component to a minor component in a mixed layer. Such subtle control of composition has been difficult to achieve using aryldiazonium salts. Herein, aryldiazonium salts of carboxyphenyl (CP) and phenylphosphorylcholine (PPC), generated in situ from their corresponding anilines, are electrografted to form molecular platform that are available for further functionalization. These two components are chosen because CP provides a convenient functionality for further coupling of biorecognition species while PPC offers resistance to nonspecific adsorption of proteins to the surface. Mixed layers of CP and PPC were prepared by grafting them either simultaneously or consecutively. The latter strategy allows an interface to be developed in a controlled way where one component is at levels of less than 1% of the total layer.
Step by step fabrication and characterization of Au (111) exposed single crystals
Publisher: IEEE
Date: 02-2010
Silicon - single molecule - silicon circuits.
Publisher: Royal Society of Chemistry (RSC)
Date: 2021
DOI: 10.1039/D1SC04943G
Abstract: Single-molecule circuits using silicon contacts are robust, conductive, controllable, and highly reproducible in blinking experiments, with enhanced conductance in break-junctions owing to residual dangling bonds.
Electroactive Self‐Assembled Monolayers of Unique Geometric Structures by Using Rigid Norbornylogous Bridges
Publisher: Wiley
Date: 23-11-2011
Abstract: Herein, we describe the synthesis of straight (S) and L-shaped (L) norbornylogous bridges (NBs) with an anthraquinone moiety at the distal end as the redox-active head group and two thiol feet at the proximal end, by which the molecules assemble on gold surfaces. The NB molecules were shown to form self-assembled monolayers (SAMs) with a well-behaved surface redox process. The SAMs were characterized by using in situ IR spectroscopy, cyclic voltammetry, scanning tunnelling microscopy and electrochemical impedance spectroscopy. The surface selection rules associated with the IR band intensities allowed the estimation of the position of the anthraquinone moiety with respect to the surface and the tilt of the bridge with respect to the surface normal, both in pure and diluted monolayers. It is shown that the S- and L-NBs hold the plane of the anthraquinone moiety close to the surface normal or the surface tangent, respectively. Neither NB molecule changes its orientation if spaced by diluents on the surface. The difference in the structure of the S- and L-NB SAMs provides a suitable framework for the investigation of factors that govern electron transfer of anthraquinone moieties across self-assembled monolayers with limited structural ambiguity, as compared with the commonly used structurally flexible alkanethiol monolayers.
Effect of Electric Fields on Silicon-Based Monolayers
Publisher: American Chemical Society (ACS)
Date: 27-02-2022
Continuous flow fabrication of green graphene oxide in aqueous hydrogen peroxide
Publisher: Royal Society of Chemistry (RSC)
Date: 2022
DOI: 10.1039/D2NA00310D
Abstract: Herein, we have established a sequential two step continuous flow process for generating graphene oxide with properties comparable to the conventional Hummers' GO. The process is high yielding and with a dramatic reduction in the generation of waste.
Tuning the electrical conductance of metalloporphyrin supramolecular wires
Publisher: Springer Science and Business Media LLC
Date: 21-11-2016
DOI: 10.1038/SREP37352
Abstract: In contrast with conventional single-molecule junctions, in which the current flows parallel to the long axis or plane of a molecule, we investigate the transport properties of M(II)-5,15-diphenylporphyrin (M-DPP) single-molecule junctions (M=Co, Ni, Cu, or Zn alent metal ions), in which the current flows perpendicular to the plane of the porphyrin. Novel STM-based conductance measurements combined with quantum transport calculations demonstrate that current-perpendicular-to-the-plane (CPP) junctions have three-orders-of-magnitude higher electrical conductances than their current-in-plane (CIP) counterparts, ranging from 2.10 −2 G 0 for Ni-DPP up to 8.10 −2 G 0 for Zn-DPP. The metal ion in the center of the DPP skeletons is strongly coordinated with the nitrogens of the pyridyl coated electrodes, with a binding energy that is sensitive to the choice of metal ion. We find that the binding energies of Zn-DPP and Co-DPP are significantly higher than those of Ni-DPP and Cu-DPP. Therefore when combined with its higher conductance, we identify Zn-DPP as the favoured candidate for high-conductance CPP single-molecule devices.
Electroconductive Hydrogel Based on Functional Poly(Ethylenedioxy Thiophene)
Publisher: American Chemical Society (ACS)
Date: 26-08-2016
Electrochemically Generated Luminescence of Luminol and Luciferin in Ionic Liquids
Publisher: Wiley
Date: 22-12-2022
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.
SARS-CoV-2 spike proteins react with Au and Si, are electrically conductive and denature at 3 × 108 V m−1: a surface bonding and a single-protein circuit study
Publisher: Royal Society of Chemistry (RSC)
Date: 2023
DOI: 10.1039/D2SC06492H
Abstract: SARS-CoV-2 spike proteins react with Au and Si, are electrically conductive as demonstrated by single-molecule scanning tunnelling break junction approaches, change structure at 1.5 × 10 8 V m −1 and denature at 3 × 10 8 V m −1 .
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.
Using reactivity predictors for enhancing the electrocatalytic activity of MN4 molecular catalysts for the oxygen reduction reaction: The role of the N-pyridinium functional group in the porphyrazine-derivative ligands
Publisher: Elsevier BV
Date: 11-2023
High shear in situ exfoliation of 2D gallium oxide sheets from centrifugally derived thin films of liquid gallium
Publisher: Royal Society of Chemistry (RSC)
Date: 2021
DOI: 10.1039/D1NA00598G
Abstract: Ultrathin gallium oxide sheets formed under continuous flow from gallium metal are highly insulating with electrocatalytic activity for hydrogen evolution.
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.
CHAPTER 5. Principles of Molecular Devices Operated by Electric Fields
Publisher: Royal Society of Chemistry
Date: 2021
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
Investigation of the Antifouling Properties of Phenyl Phosphorylcholine-Based Modified Gold Surfaces
Publisher: Wiley
Date: 19-05-2014
Advances in single-molecule junctions as tools for chemical and biochemical analysis
Publisher: Springer Science and Business Media LLC
Date: 27-04-2023
Chemically and Mechanically Controlled Single-Molecule Switches Using Spiropyrans
Publisher: American Chemical Society (ACS)
Date: 16-09-2019
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.
Impermeable Graphene Oxide Protects Silicon from Oxidation
Publisher: American Chemical Society (ACS)
Date: 03-08-2021
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.
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.
Spontaneous Grafting of OH-Terminated Molecules on Si−H Surfaces via Si–O–C Covalent Bonding
Publisher: MDPI AG
Date: 05-03-2021
Abstract: The surface functionalization of oxide-free hydrogen-terminated silicon (Si−H) enables predictably tuning its electronic properties, by incorporating tailored functionality for applications such as photovoltaics, biosensing and molecular electronics devices. Most of the available chemical functionalization approaches require an external radical initiator, such as UV light, heat or chemical reagents. Here, we report forming organic monolayers on Si–H surfaces using molecules comprising terminal alcohol (–OH) groups. Self-assembled monolayer (SAM) formation is spontaneous, requires no external stimuli–and yields Si–O–C covalently bound monolayers. The SAMs were characterized by X-ray photoelectron spectroscopy (XPS) to determine the chemical bonding, by X-ray reflectometry (XRR) to determine the monolayers thicknesses on the surface and by atomic force microscopy (AFM) to probe surface topography and surface roughness. The redox activity and the electrochemical properties of the SAMs were studied using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The availability and the ease of incorporating OH groups in organic molecules, makes this spontaneous grafting as a reliable method to attach molecules to Si surfaces in applications ranging from sensing to molecular electronics where incorporating radical initiator setups is not accessible.
Controlling piezoresistance in single molecules through the isomerisation of bullvalenes
Publisher: Springer Science and Business Media LLC
Date: 21-09-0008
Switching of Current Rectification Ratios within a Single Nanocrystal by Facet-Resolved Electrical Wiring
Publisher: American Chemical Society (ACS)
Date: 06-07-2018
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
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
Highly Conductive Single-Molecule Wires with Controlled Orientation by Coordination of Metalloporphyrins
Publisher: American Chemical Society (ACS)
Date: 03-07-2014
DOI: 10.1021/NL501884G
Electrochemically fabricated molecule–electrode contacts for molecular electronics
Publisher: Elsevier BV
Date: 08-2022
Terminal Deuterium Atoms Protect Silicon from Oxidation
Publisher: American Chemical Society (ACS)
Date: 28-09-2023
On-Surface Azide–Alkyne Cycloaddition Reaction: Does It Click with Ruthenium Catalysts?
Publisher: American Chemical Society (ACS)
Date: 26-04-2022
Vortex fluidic mediated transformation of graphite into highly conducting graphene scrolls
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C9NA00184K
Abstract: A facile one step process has been developed to fabricate high yield graphene scrolls directly from graphite flakes using a sustainable metrics, with the 3D nanomaterial having remarkable properties, unraveling into buckled graphene sheets °C and forming highly conducting electrical contacts.
Harnessing silicon facet-dependent conductivity to enhance the direct-current produced by a sliding Schottky diode triboelectric nanogenerator
Publisher: Elsevier BV
Date: 12-2020
Luciferase‐free Luciferin Electrochemiluminescence
Publisher: Wiley
Date: 25-10-2022
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
The Surface Potential of Zero Charge Controls the Kinetics of Diazonium Salts Electropolymerization
Publisher: Wiley
Date: 22-07-2022
Abstract: One of the central fundamental properties of solid/liquid interfaces is the potential of zero charge (pzc), where no excess charge prevails at the electrode surface. Applying potential on either side of the pzc can control adsorption of molecules on surfaces and is paramount for any interfacial process. However, the impact of pzc on electrode processes has been only demonstrated for reactions involving the adsorption of inorganic ions and gases. Here, the direct relationship between the pzc and electropolymerization rate of a small organic molecule was reported. The electrochemical reduction of diazonium salts, which are the most commonly used molecules to form thin films of molecules on electrode surfaces, was tested. The kinetics of the surface reaction and the reduction potential in electrochemical measurements depended on the pzc of the surface following the order of gold latinum carbon indium‐tin‐oxide fluorine‐doped tin‐oxide silicon hydride. The immediate consequence of this finding was that the concentration of the diazonium salt molecules became critical in defining the electrochemical reduction mechanism. At higher concentrations, the mechanism was pzc‐controlled adsorption‐dominated inner‐sphere electron transfer whereas at lower concentrations, diffusion‐based outer‐sphere electron transfer dominated.
Nanoscale Silicon Oxide Reduces Electron Transfer Kinetics of Surface-Bound Ferrocene Monolayers on Silicon
Publisher: American Chemical Society (ACS)
Date: 12-12-2021
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
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.
Ultra-Small Fatty Acid-Stabilized Magnetite Nanocolloids Synthesized byIn SituHydrolytic Precipitation
Publisher: Hindawi Limited
Date: 2015
DOI: 10.1155/2015/620672
Abstract: Simple, fast, large-scale, and cost-effective preparation of uniform controlled magnetic nanoparticles remains a major hurdle on the way towards magnetically targeted applications at realistic technical conditions. Herein, we present a unique one-pot approach that relies on simple basic hydrolytic in situ coprecipitation of inexpensive metal salts (Fe 2+ and Fe 3+ ) compartmentalized by stabilizing fatty acids and aided by the presence of alkylamines. The synthesis was performed at relatively low temperatures (~80°C) without the use of high-boiling point solvents and elevated temperatures. This method allowed for the production of ultra-small, colloidal, and hydrophobically stabilized magnetite metal oxide nanoparticles readily dispersed in organic solvents. The results reveal that the obtained magnetite nanoparticles exhibit narrow size distributions, good monodispersities, high saturation magnetizations, and excellent colloidal stabilities. When the [fatty acid] : [Fe] ratio was varied, control over nanoparticle diameters within the range of 2–10 nm was achieved. The amount of fatty acid and alkylamine used during the reaction proved critical in governing morphology, dispersity, uniformity, and colloidal stability. Upon exchange with water-soluble polymers, the ultra-small sized particles become biologically relevant, with great promise for theranostic applications as imaging and magnetically targeted delivery vehicles.
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
Static Electrification of Plastics under Friction: The Position of Engineering‐Grade Polyethylene Terephthalate in the Triboelectric Series
Publisher: Wiley
Date: 13-12-2020
Titelbild: Luciferase‐free Luciferin Electrochemiluminescence (Angew. Chem. 46/2022)
Publisher: Wiley
Date: 27-10-2022
Nucleic-acid recognition interfaces: how the greater ability of RNA duplexes to bend towards the surface influences electrochemical sensor performance
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C5CC05450H
Abstract: Faster electron transfer kinetics were observed for redox labelled nucleic-acids duplexes containing RNA, suggesting a more flexibility, compared to DNA/DNA.
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Single-molecule Circuitry For Nanoscale Electronic Devices
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End Date: 2019
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View Funded ActivityDeveloping Single-molecule Switches For Applications In Nanoscale Organic Devices
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End Date: 2015
Funder: European Commission
View Funded ActivityLinkage Infrastructure, Equipment And Facilities - Grant ID: LE230100019
Start Date: 2023
End Date: 12-2023
Amount: $690,000.00
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View Funded ActivityDiscovery Projects - Grant ID: DP190100735
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End Date: 12-2022
Amount: $310,000.00
Funder: Australian Research Council
View Funded ActivityDiscovery Early Career Researcher Award - Grant ID: DE160101101
Start Date: 05-2016
End Date: 04-2019
Amount: $348,741.00
Funder: Australian Research Council
View Funded ActivityLinkage Infrastructure, Equipment And Facilities - Grant ID: LE210100126
Start Date: 07-2021
End Date: 07-2022
Amount: $527,638.00
Funder: Australian Research Council
View Funded Activity