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Vogel YB, Pham LN, Stam M, Ubbink RF, Coote ML, Houtepen AJ. Solvation Shifts the Band-Edge Position of Colloidal Quantum Dots by Nearly 1 eV. J Am Chem Soc 2024; 146:9928-9938. [PMID: 38530865 PMCID: PMC11009959 DOI: 10.1021/jacs.4c00402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2024] [Revised: 02/23/2024] [Accepted: 02/27/2024] [Indexed: 03/28/2024]
Abstract
The optoelectronic properties of colloidal quantum dots (cQDs) depend critically on the absolute energy of the conduction and valence band edges. It is well known these band-edge energies are sensitive to the ligands on the cQD surface, but it is much less clear how they depend on other experimental conditions, like solvation. Here, we experimentally determine the band-edge positions of thin films of PbS and ZnO cQDs via spectroelectrochemical measurements. To achieve this, we first carefully evaluate and optimize the electrochemical injection of electrons and holes into PbS cQDs. This results in electrochemically fully reversible electron injection with >8 electrons per PbS cQDs, allowing the quantitative determination of the conduction band energy for PbS cQDs with various diameters and surface compositions. Surprisingly, we find that the band-edge energies shift by nearly 1 eV in the presence of different solvents, a result that also holds true for ZnO cQDs. We argue that complexation and partial charge transfer between solvent and surface ions are responsible for this large effect of the solvent on the band-edge energy. The trend in the energy shift matches the results of density functional theory (DFT) calculations in explicit solvents and scales with the energy of complexation between surface cations and solvents. As a first approximation, the solvent Lewis basicity can be used as a good descriptor to predict the shift of the conduction and valence band edges of solvated cQDs.
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Affiliation(s)
- Yan B. Vogel
- Department
of Chemical Engineering, Delft University
of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands
| | - Le Nhan Pham
- Institute
for Nanoscale Science and Technology, College of Science and Engineering, Flinders University, Bedford Park, South Australia 5042, Australia
| | - Maarten Stam
- Department
of Chemical Engineering, Delft University
of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands
| | - Reinout F. Ubbink
- Department
of Chemical Engineering, Delft University
of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands
| | - Michelle L. Coote
- Institute
for Nanoscale Science and Technology, College of Science and Engineering, Flinders University, Bedford Park, South Australia 5042, Australia
| | - Arjan J. Houtepen
- Department
of Chemical Engineering, Delft University
of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands
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2
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Ubbink R, Gudjonsdottir S, Vogel YB, Houtepen AJ. Numerical Model to Simulate Electrochemical Charging of Nanocrystal Films. J Phys Chem C Nanomater Interfaces 2023; 127:9896-9902. [PMID: 37255927 PMCID: PMC10226107 DOI: 10.1021/acs.jpcc.3c01562] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Revised: 04/17/2023] [Indexed: 06/01/2023]
Abstract
Electrochemical charging of nanocrystal films opens up new possibilities for designing quantum dot-based device structures, but a solid theoretical framework of this process and its limitations is lacking. In this work, drift-diffusion simulations are employed to model the charging of nanocrystal films and gain insight into the electrochemical doping process. Through steady state simulations it is shown that the Fermi level and doping density in the nanocrystal film depend on the concentration of the electrolyte in addition to the value of the applied potential. Time-resolved simulations reveal that charging is often limited by transport of electrolyte ions. However, ion transport in the film is dominated by drift, rather than diffusion, and the concentration profile of ions differs substantially from concentration profiles of diffusing redox species at flat electrodes. Classical electrochemical theory cannot be used to model this type of mass transport limited behavior in films of nanocrystals, so a new model is developed. We show that the Randles-Ševčík equation, which is derived for electrochemical species diffusing in solution, but is often applied to films as well, results in a significant underestimation of the diffusion coefficients of the charge compensating electrolyte ions.
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3
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Vogel YB, Stam M, Mulder JT, Houtepen AJ. Long-Range Charge Transport via Redox Ligands in Quantum Dot Assemblies. ACS Nano 2022; 16:21216-21224. [PMID: 36516407 PMCID: PMC9798906 DOI: 10.1021/acsnano.2c09192] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Accepted: 12/12/2022] [Indexed: 06/02/2023]
Abstract
We present a strategy to actively engineer long-range charge transport in colloidal quantum dot assemblies by using ligand functionalities that introduce electronic states and provide a path for carrier transfer. This is a shift away from the use of inactive spacers to modulate charge transport through the lowering of the tunneling barrier for interparticle carrier transfer. This is accomplished with the use of electronically coupled redox ligands by which a self-exchange chain reaction takes place and long-range charge transport is enabled across the film. We identified the different modes of charge transport in these quantum dot/redox ligand assemblies, their energetic position and kinetics, and explain how to rationally manipulate them through modulation of the Fermi level and redox ligand coverage.
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Zhang S, Ferrie S, Peiris CR, Lyu X, Vogel YB, Darwish N, Ciampi S. Common Background Signals in Voltammograms of Crystalline Silicon Electrodes are Reversible Silica-Silicon Redox Chemistry at Highly Conductive Surface Sites. J Am Chem Soc 2021; 143:1267-1272. [PMID: 33373229 DOI: 10.1021/jacs.0c10713] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The electrochemical reduction of bulk silica, due to its high electrical resistance, is of limited viability, namely, requiring temperatures in excess of 850 °C. By means of electrochemical and electrical measurements in atomic force microscopy, we demonstrate that at a buried interface, where silica has grown on highly conductive Si(110) crystal facets, the silica-silicon conversion becomes reversible at room temperature and accessible within a narrow potential window. We conclude that parasitic signals commonly observed in voltammograms of silicon electrodes originate from silica-silicon redox chemistry. While these findings do not remove the requirement of high temperature toward bulk silica electrochemical reduction, they redefine for silicon the potential window free from parasitic signals and, as such, significantly restrict the conditions where electroanalytical methods can be applied to the study of silicon surface reactivity.
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Affiliation(s)
- Song Zhang
- School of Molecular and Life Sciences, Curtin Institute of Functional Molecules and Interfaces, Curtin University, Bentley, Western Australia 6102, Australia
| | - Stuart Ferrie
- School of Molecular and Life Sciences, Curtin Institute of Functional Molecules and Interfaces, Curtin University, Bentley, Western Australia 6102, Australia
| | - Chandramalika R Peiris
- School of Molecular and Life Sciences, Curtin Institute of Functional Molecules and Interfaces, Curtin University, Bentley, Western Australia 6102, Australia
| | - Xin Lyu
- School of Molecular and Life Sciences, Curtin Institute of Functional Molecules and Interfaces, Curtin University, Bentley, Western Australia 6102, Australia
| | - Yan B Vogel
- School of Molecular and Life Sciences, Curtin Institute of Functional Molecules and Interfaces, Curtin University, Bentley, Western Australia 6102, Australia
| | - Nadim Darwish
- School of Molecular and Life Sciences, Curtin Institute of Functional Molecules and Interfaces, Curtin University, Bentley, Western Australia 6102, Australia
| | - Simone Ciampi
- School of Molecular and Life Sciences, Curtin Institute of Functional Molecules and Interfaces, Curtin University, Bentley, Western Australia 6102, Australia
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Dief EM, Vogel YB, Peiris CR, Le Brun AP, Gonçales VR, Ciampi S, Reimers JR, Darwish N. Covalent Linkages of Molecules and Proteins to Si-H Surfaces Formed by Disulfide Reduction. Langmuir 2020; 36:14999-15009. [PMID: 33271017 DOI: 10.1021/acs.langmuir.0c02391] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Thiols and disulfide contacts have been, for decades, key for connecting organic molecules to surfaces and nanoclusters as they form self-assembled monolayers (SAMs) on metals such as gold (Au) under mild conditions. In contrast, they have not been similarly deployed on Si owing to the harsh conditions required for monolayer formation. Here, we show that SAMs can be simply formed by dipping Si-H surfaces into dilute solutions of organic molecules or proteins comprising disulfide bonds. We demonstrate that S-S bonds can be spontaneously reduced on Si-H, forming covalent Si-S bonds in the presence of traces of water, and that this grafting can be catalyzed by electrochemical potential. Cyclic disulfide can be spontaneously reduced to form complete monolayers in 1 h, and the reduction can be catalyzed electrochemically to form full surface coverages within 15 min. In contrast, the kinetics of SAM formation of the cyclic disulfide molecule on Au was found to be three-fold slower than that on Si. It is also demonstrated that dilute thiol solutions can form monolayers on Si-H following oxidation to disulfides under ambient conditions; the supply of too much oxygen, however, inhibits SAM formation. The electron transfer kinetics of the Si-S-enabled SAMs on Si-H is comparable to that on Au, suggesting that Si-S contacts are electrically transmissive. We further demonstrate the prospect of this spontaneous disulfide reduction by forming a monolayer of protein azurin on a Si-H surface within 1 h. The direct reduction of disulfides on Si electrodes presents new capabilities for a range of fields, including molecular electronics, for which highly conducting SAM-electrode contacts are necessary and for emerging fields such as biomolecular electronics as disulfide linkages could be exploited to wire proteins between Si electrodes, within the context of the current Si-based technologies.
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Affiliation(s)
- Essam M Dief
- School of Molecular and Life Sciences, Curtin Institute of Functional Molecules and Interfaces, Curtin University, Bentley, Western Australia 6102, Australia
| | - Yan B Vogel
- School of Molecular and Life Sciences, Curtin Institute of Functional Molecules and Interfaces, Curtin University, Bentley, Western Australia 6102, Australia
| | - Chandramalika R Peiris
- School of Molecular and Life Sciences, Curtin Institute of Functional Molecules and Interfaces, Curtin University, Bentley, Western Australia 6102, Australia
| | - Anton P Le Brun
- Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organization (ANSTO), Lucas Heights, New South Wales 2234, Australia
| | - Vinicius R Gonçales
- School of Chemistry, Australia Centre for NanoMedicine, ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, University of New South Wales, Sydney, New South Wales 2052, Australia
| | - Simone Ciampi
- School of Molecular and Life Sciences, Curtin Institute of Functional Molecules and Interfaces, Curtin University, Bentley, Western Australia 6102, Australia
| | - Jeffrey R Reimers
- International Centre for Quantum and Molecular Structures, School of Physics, Shanghai University, Shanghai 200444, China
- School of Mathematical and Physical Sciences, University of Technology Sydney, Ultimo, New South Wales 2007, Australia
| | - Nadim Darwish
- School of Molecular and Life Sciences, Curtin Institute of Functional Molecules and Interfaces, Curtin University, Bentley, Western Australia 6102, Australia
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Vogel YB, Evans CW, Belotti M, Xu L, Russell IC, Yu LJ, Fung AKK, Hill NS, Darwish N, Gonçales VR, Coote ML, Swaminathan Iyer K, Ciampi S. The corona of a surface bubble promotes electrochemical reactions. Nat Commun 2020; 11:6323. [PMID: 33303749 PMCID: PMC7729901 DOI: 10.1038/s41467-020-20186-0] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Accepted: 11/11/2020] [Indexed: 11/23/2022] Open
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. Gas bubbles forming on the surface of an electrode, a phenomenon common to several industrial electrolytic processes, are usually perceived as inert, passivating entities. Here, the authors show that that this general assumption does not hold for gas bubbles masking anodes operating in water.
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Affiliation(s)
- Yan B Vogel
- School of Molecular and Life Sciences, Curtin Institute of Functional Molecules and Interfaces, Curtin University, Bentley, WA, 6102, Australia
| | - Cameron W Evans
- School of Molecular Sciences, The University of Western Australia, Crawley, WA, 6009, Australia
| | - Mattia Belotti
- School of Molecular and Life Sciences, Curtin Institute of Functional Molecules and Interfaces, Curtin University, Bentley, WA, 6102, Australia
| | - Longkun Xu
- ARC Centre of Excellence for Electromaterials Science, Research School of Chemistry, Australian National University, Canberra, ACT, 2601, Australia
| | - Isabella C Russell
- ARC Centre of Excellence for Electromaterials Science, Research School of Chemistry, Australian National University, Canberra, ACT, 2601, Australia
| | - Li-Juan Yu
- ARC Centre of Excellence for Electromaterials Science, Research School of Chemistry, Australian National University, Canberra, ACT, 2601, Australia
| | - Alfred K K Fung
- ARC Centre of Excellence for Electromaterials Science, Research School of Chemistry, Australian National University, Canberra, ACT, 2601, Australia
| | - Nicholas S Hill
- ARC Centre of Excellence for Electromaterials Science, Research School of Chemistry, Australian National University, Canberra, ACT, 2601, Australia
| | - Nadim Darwish
- School of Molecular and Life Sciences, Curtin Institute of Functional Molecules and Interfaces, Curtin University, Bentley, WA, 6102, Australia
| | - Vinicius R Gonçales
- School of Chemistry, Australian Centre for NanoMedicine and Australian Research Council Centre of Excellence in Convergent Bio-Nano Science and Technology, University of New South Wales, Sydney, NSW, 2052, Australia
| | - Michelle L Coote
- ARC Centre of Excellence for Electromaterials Science, Research School of Chemistry, Australian National University, Canberra, ACT, 2601, Australia.
| | - K Swaminathan Iyer
- School of Molecular Sciences, The University of Western Australia, Crawley, WA, 6009, Australia.
| | - Simone Ciampi
- School of Molecular and Life Sciences, Curtin Institute of Functional Molecules and Interfaces, Curtin University, Bentley, WA, 6102, Australia.
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Gautam S, Lian J, R. Gonçales V, Vogel YB, Ciampi S, Tilley RD, Gooding JJ. Surface Patterning of Biomolecules Using Click Chemistry and Light‐Activated Electrochemistry to Locally Generate Cu(I). ChemElectroChem 2020. [DOI: 10.1002/celc.202001097] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Shreedhar Gautam
- School of Chemistry Australian Centre of NanoMedicine and ARC Centre of Excellence in Convergent Bio-Nano Science and Technology The University of New South Wales Sydney 2052 Australia
| | - Jiaxin Lian
- School of Chemistry Australian Centre of NanoMedicine and ARC Centre of Excellence in Convergent Bio-Nano Science and Technology The University of New South Wales Sydney 2052 Australia
| | - Vinicius R. Gonçales
- School of Chemistry Australian Centre of NanoMedicine and ARC Centre of Excellence in Convergent Bio-Nano Science and Technology The University of New South Wales Sydney 2052 Australia
| | - Yan B. Vogel
- School of Molecular and Life Sciences Curtin Institute of Functional Molecules and Interfaces Curtin University Bentley 6102 WA Australia
| | - Simone Ciampi
- School of Molecular and Life Sciences Curtin Institute of Functional Molecules and Interfaces Curtin University Bentley 6102 WA Australia
| | - Richard D. Tilley
- School of Chemistry Australian Centre of NanoMedicine and ARC Centre of Excellence in Convergent Bio-Nano Science and Technology The University of New South Wales Sydney 2052 Australia
- Electron Microscope Unit Mark Wainwright Analytical Centre The University of New South Wales Sydney 2052 Australia
| | - J. Justin Gooding
- School of Chemistry Australian Centre of NanoMedicine and ARC Centre of Excellence in Convergent Bio-Nano Science and Technology The University of New South Wales Sydney 2052 Australia
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Peiris CR, Vogel YB, Le Brun AP, Aragonès AC, Coote ML, Díez-Pérez I, Ciampi S, Darwish N. Metal-Single-Molecule-Semiconductor Junctions Formed by a Radical Reaction Bridging Gold and Silicon Electrodes. J Am Chem Soc 2019; 141:14788-14797. [PMID: 31455076 DOI: 10.1021/jacs.9b07125] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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.
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Affiliation(s)
- Chandramalika R Peiris
- School of Molecular and Life Sciences, Curtin Institute of Functional molecules and Interfaces , Curtin University , Bentley , Western Australia 6102 , Australia
| | - Yan B Vogel
- School of Molecular and Life Sciences, Curtin Institute of Functional molecules and Interfaces , Curtin University , Bentley , Western Australia 6102 , Australia
| | - Anton P Le Brun
- Australian Centre for Neutron Scattering , Australian Nuclear Science and Technology Organization (ANSTO) , Lucas Heights , New South Wales 2234 , Australia
| | - Albert C Aragonès
- Department of Chemistry, Faculty of Natural & Mathematical Sciences , King's College London , Britannia House, 7 Trinity Street , London SE1 1DB , United Kingdom
| | - Michelle L Coote
- ARC Centre of Excellence for Electromaterials Science, Research School of Chemistry , Australian National University , Canberra , Australian Capital Territory 2601 , Australia
| | - Ismael Díez-Pérez
- Department of Chemistry, Faculty of Natural & Mathematical Sciences , King's College London , Britannia House, 7 Trinity Street , London SE1 1DB , United Kingdom
| | - Simone Ciampi
- School of Molecular and Life Sciences, Curtin Institute of Functional molecules and Interfaces , Curtin University , Bentley , Western Australia 6102 , Australia
| | - Nadim Darwish
- School of Molecular and Life Sciences, Curtin Institute of Functional molecules and Interfaces , Curtin University , Bentley , Western Australia 6102 , Australia
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9
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Vogel YB, Gooding JJ, Ciampi S. Light-addressable electrochemistry at semiconductor electrodes: redox imaging, mask-free lithography and spatially resolved chemical and biological sensing. Chem Soc Rev 2019; 48:3723-3739. [PMID: 31143897 DOI: 10.1039/c8cs00762d] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Spatial confinement of electrochemical reactions at solid/liquid interfaces is a mature area of research, and a central theme from cell biology to analytical chemistry. Monitoring or manipulating the kinetics of a charge transfer reaction in 2D is generally achieved using scanning electrochemical microscopy or multielectrode arrays, techniques that rely on moving physical probes or on a network of electrical connections. This tutorial is introducing concepts and instruments to confine faradaic electrochemical reactions in 2D without resorting to the mechanical movement of a probe, and with the simple design of one semiconducting electrode, one electrical lead and a single-channel potentiostat. We provide a theoretical background of semiconductor electrochemistry, and describe the use of localised visible light stimuli on photoconductor/liquid and semiconductor/liquid interfaces to address electrical conductivity - hence chemical reactivity - only at one specific site defined by the experimentalist. This enables shifting of the tenet of one electrode/one wire towards one wire/many electrodes. We discuss the applications of this emerging platform in the context of surface chemistry patterning, redox imaging, chemical and biological sensing, generating chemical gradients, electrocatalysis, nanotechnology and cell biology.
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Affiliation(s)
- Yan B Vogel
- Department of Chemistry, Curtin Institute of Functional Molecules and Interfaces, Curtin University, Bentley, Western Australia 6102, Australia.
| | - J Justin Gooding
- School of Chemistry, The Australian Centre for NanoMedicine and the Centre of Excellence in Convergent Bio-Nano Science and Technology, The University of New South Wales, Sydney, New South Wales 2052, Australia.
| | - Simone Ciampi
- Department of Chemistry, Curtin Institute of Functional Molecules and Interfaces, Curtin University, Bentley, Western Australia 6102, Australia.
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Vogel YB, Molina A, Gonzalez J, Ciampi S. Quantitative Analysis of Cyclic Voltammetry of Redox Monolayers Adsorbed on Semiconductors: Isolating Electrode Kinetics, Lateral Interactions, and Diode Currents. Anal Chem 2019; 91:5929-5937. [PMID: 30938142 DOI: 10.1021/acs.analchem.9b00336] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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.
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Affiliation(s)
- Yan B Vogel
- Curtin Institute of Functional Molecules and Interfaces , Curtin University , Bentley , Western Australia 6102 , Australia
| | - Angela Molina
- Departamento de Quimica Fisica , Universidad de Murcia , Murcia 30003 , Spain
| | - Joaquin Gonzalez
- Departamento de Quimica Fisica , Universidad de Murcia , Murcia 30003 , Spain
| | - Simone Ciampi
- Curtin Institute of Functional Molecules and Interfaces , Curtin University , Bentley , Western Australia 6102 , Australia
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Zhang J, Rogers FJM, Darwish N, Gonçales VR, Vogel YB, Wang F, Gooding JJ, Peiris MCR, Jia G, Veder JP, Coote ML, Ciampi S. Electrochemistry on Tribocharged Polymers Is Governed by the Stability of Surface Charges Rather than Charging Magnitude. J Am Chem Soc 2019; 141:5863-5870. [DOI: 10.1021/jacs.9b00297] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- Jinyang Zhang
- School of Molecular and Life Sciences, Curtin Institute of Functional Molecules and Interfaces, Curtin University, Bentley, Western Australia 6102, Australia
| | - Fergus J. M. Rogers
- ARC Centre of Excellence for Electromaterials Science, Research School of Chemistry, Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Nadim Darwish
- School of Molecular and Life Sciences, Curtin Institute of Functional Molecules and Interfaces, Curtin University, Bentley, Western Australia 6102, Australia
| | - Vinicius R. Gonçales
- School of Chemistry, The Australian Centre for NanoMedicine and the Centre of Excellence in Convergent Bio-Nano Science and Technology, The University of New South Wales, Sydney, New South Wales 2052, Australia
| | - Yan B. Vogel
- School of Molecular and Life Sciences, Curtin Institute of Functional Molecules and Interfaces, Curtin University, Bentley, Western Australia 6102, Australia
| | - Fei Wang
- School of Molecular and Life Sciences, Curtin Institute of Functional Molecules and Interfaces, Curtin University, Bentley, Western Australia 6102, Australia
| | - J. Justin Gooding
- School of Chemistry, The Australian Centre for NanoMedicine and the Centre of Excellence in Convergent Bio-Nano Science and Technology, The University of New South Wales, Sydney, New South Wales 2052, Australia
| | - M. Chandramalika. R. Peiris
- School of Molecular and Life Sciences, Curtin Institute of Functional Molecules and Interfaces, Curtin University, Bentley, Western Australia 6102, Australia
| | - Guohua Jia
- School of Molecular and Life Sciences, Curtin Institute of Functional Molecules and Interfaces, Curtin University, Bentley, Western Australia 6102, Australia
| | - Jean-Pierre Veder
- John de Laeter Centre, Curtin University, Bentley, Western Australia 6102, Australia
| | - Michelle L. Coote
- ARC Centre of Excellence for Electromaterials Science, Research School of Chemistry, Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Simone Ciampi
- School of Molecular and Life Sciences, Curtin Institute of Functional Molecules and Interfaces, Curtin University, Bentley, Western Australia 6102, Australia
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Vogel YB, Zhang J, Darwish N, Ciampi S. Switching of Current Rectification Ratios within a Single Nanocrystal by Facet-Resolved Electrical Wiring. ACS Nano 2018; 12:8071-8080. [PMID: 29979571 DOI: 10.1021/acsnano.8b02934] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
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 individual p-n rectifier (a Cu2O nanocrystal on silicon) the degree of current asymmetry can be modulated predictably by a set of geometric considerations. We demonstrate the concept of a single nanoscale entity displaying an in-built range of discrete electrical signatures and address fundamental questions in the direction of "landing" contacts in single-particle diodes. This concept is scalable to large 2D arrays, up to millimeters in size, with implications in the design and understanding of nanoparticle circuitry.
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Affiliation(s)
- Yan B Vogel
- Department of Chemistry, Curtin Institute of Functional Molecules and Interfaces , Curtin University , Bentley , Western Australia 6102 , Australia
| | - Jinyang Zhang
- Department of Chemistry, Curtin Institute of Functional Molecules and Interfaces , Curtin University , Bentley , Western Australia 6102 , Australia
| | - Nadim Darwish
- Department of Chemistry, Curtin Institute of Functional Molecules and Interfaces , Curtin University , Bentley , Western Australia 6102 , Australia
| | - Simone Ciampi
- Department of Chemistry, Curtin Institute of Functional Molecules and Interfaces , Curtin University , Bentley , Western Australia 6102 , Australia
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Vogel YB, Darwish N, Kashi MB, Gooding JJ, Ciampi S. Hydrogen evolution during the electrodeposition of gold nanoparticles at Si(100) photoelectrodes impairs the analysis of current-time transients. Electrochim Acta 2017. [DOI: 10.1016/j.electacta.2017.06.126] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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