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Richard G. Compton - One of the best experts on this subject based on the ideXlab platform.
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nanoparticle Modified Electrodes can show an apparent increase in electrode kinetics due solely to altered surface geometry the effective electrochemical rate constant for non flat and non uniform electrode surfaces
Journal of Electroanalytical Chemistry, 2013Co-Authors: Kristopher R Ward, Matthew Gara, Nathan S Lawrence, Seth R Hartshorne, Richard G. ComptonAbstract:Abstract The voltammetry of micro- and nano-particle Modified Electrodes and other Electrodes of partially covered and non-planar geometry is investigated by simulation. Building on existing theory, it is demonstrated that for a simple one-electron process (assuming that the diffusion fields of neighbouring electroactive regions strongly overlap such that diffusion to the entire surface is linear), the apparent electrochemical rate constant of the reaction, k app , is equal to the product of the true rate constant, k 0 , and the ratio, Ψ, of the total electroactive surface area to the geometric surface area of the substrate. It is demonstrated that for a given value of Ψ, the voltammetry is independent of the surface geometry; surfaces covered by, for example, long thin bands of electroactive material, or electroactive hemispherical or spherical particles, show the same voltammetry if they have the same surface area of electroactive material per area of substrate. Distributions of, most importantly, electroactive nanoparticles, with Ψ > 1 , will display an apparent catalytic effect compared to the bulk material which can be solely due to the geometry of the surface and not necessarily related to changes in kinetics at the nanoscale, for example by altered structural or electronic properties. Further, if an electrode surface is Modified by a fixed mass of nanocatalyst per unit area, then the response will reflect the size and shape of the Modified particles.
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the use of nano carbon as an alternative to multi walled carbon nanotubes in Modified Electrodes for adsorptive stripping voltammetry
Sensors and Actuators B-chemical, 2012Co-Authors: Tsz W B Lo, Leigh Aldous, Richard G. ComptonAbstract:Abstract We report the advantageous use of nano-carbon black as a much cheaper alternative to multiwalled carbon nanotubes as an electrode modifier for use in adsorptive stripping voltammetry. Namely, the adsorptive stripping voltammetry (AdsSV) of nicotine is compared and contrasted at an unModified glassy carbon (GC) electrode and GC Electrodes Modified with either bamboo multiwalled carbon nanotubes (MWCNT) or carbon black. The approximately spherical, primary carbon black particles used possessed an average radius of 7 nm, and are a form of ‘nano-carbon’. Their immobilisation on a GC resulted in a nanostructured surface with a large active surface area. Cyclic Voltammetry (CV), Square Wave Voltammetry (SWV) and Differential Pulse Voltammetry (DPV) were performed using the various systems. SWV resulted in a Limit of Detection (LOD) of 12.4 ± 0.2 μM at bare GC. CV gave the lowest LOD results for MWCNT and nano-carbon Modified Electrodes, with LOD values of 5.0 ± 0.3 and 2.0 ± 0.3 μM. Nano-carbon is highlighted to be a cheap, highly effective electrode modifier which facilitates the electroanalytical quantification of physiologically relevant concentrations of nicotine by AdsSV.
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using multiwalled carbon nanotube Modified Electrodes for the adsorptive striping voltammetric determination of hesperidin
Electrochimica Acta, 2009Co-Authors: Marcus J Sims, Gregory G Wildgoose, Roohollah Torabi Kachoosangi, Richard G. ComptonAbstract:Abstract Hesperidin, a flavone glycoside found in the skins and juices of citrus fruits, can be detected using multiwalled carbon nanotube (MWCNT)-Modified Electrodes using the technique of adsorptive stripping voltammetry (AdSV) with accumulation at open circuit potential. This is relevant because hesperidin can be used as an indication of the citrus fruit juice's freshness. The oxidation mechanism to explain the observed voltammetry corresponds to the redox chemistry of the guaiacol sub-unit within the hesperidin molecular structure. Hesperidin could be detected over a linear range up to 30 μM, and with a detection limit of 0.61 μM and 7 nM, with less than 5% variation between different Electrodes, using cyclic voltammetric or square wave adsorptive stripping techniques respectively. This methodology was extended to MWCNT-Modified screen-printed Electrodes (MWCNT-SPEs), allowing the development of a cheap, mass produced, disposable sensor that we show is capable of measuring the concentration of hesperidin in real orange juice samples, and be applied within the citrus fruit industry.
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exploring the origins of the apparent electrocatalysis observed at c60 film Modified Electrodes
Sensors and Actuators B-chemical, 2009Co-Authors: Lei Xiao, Gregory G Wildgoose, Richard G. ComptonAbstract:We have recently revised the oft-cited model of cation insertion into electroreduced C60 film-Modified Electrodes in aqueous, basic electrolytes [L. Xiao, G.G. Wildgoose, A. Crossley, R.G. Compton, The electroreduction of “C60” films in aqueous electrolyte does not lead to alkali metal ion insertion—evidence for the involvement of adventitious poly-epoxidated C60 (C60On), submitted for publication]. Instead we have proposed that the observed reduction corresponds to adventitious polyepoxidated C60On within the starting material [L. Xiao, G.G. Wildgoose, A. Crossley, R.G. Compton, The electroreduction of “C60” films in aqueous electrolyte does not lead to alkali metal ion insertion—evidence for the involvement of adventitious poly-epoxidated C60 (C60On), submitted for publication]. In this paper, we further show, using scanning electron microscopy and cyclic voltammetry of ascorbic acid, how our alternative model can be used to explain both the voltammetric behaviour observed during the reduction of “C60” films in aqueous electrolytes, and how the structure of these films can give rise to misleading claims of apparent “electrocatalytic” behaviour. The latter arises due to restructuring of the deposited C60 film giving rise to a porous, partially blocked electrode, coupled with possible thin-layer effects. We find no evidence that C60 itself is reduced within the potential window offered by aqueous electrolytes, nor that it is involved in any form of electron mediation or electrocatalysis.
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cyclic voltammetry on electrode surfaces covered with porous layers an analysis of electron transfer kinetics at single walled carbon nanotube Modified Electrodes
Sensors and Actuators B-chemical, 2008Co-Authors: Ian Streeter, Gregory G Wildgoose, Lidong Shao, Richard G. ComptonAbstract:Cyclic voltammetry is recorded of the oxidation of ferrocyanide on a glassy carbon electrode Modified with multiple layers of single-walled carbon nanotubes. The current response is interpreted in terms of semi-infinite planar diffusion towards the macro-electrode surface and in terms of oxidation of the electroactive species trapped in pockets in between the nanotubes. A thin layer model is used to illustrate the effects of diffusion within a porous layer. It is found that a semi-infinite planar diffusion model alone is not appropriate for interpreting the kinetics of the electron transfer at this electrode surface. In particular, caution should be exercised in respect of comparing voltammetric peak-to-peak potential separations between naked Electrodes and nanotube-Modified Electrodes for the inference of electrocatalysis via electron transfer via the nanotubes.
Craig E Banks - One of the best experts on this subject based on the ideXlab platform.
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2D nanosheet molybdenum disulphide (MoS2) Modified Electrodes explored towards the hydrogen evolution reaction
Nanoscale, 2015Co-Authors: Samuel J. Rowley-Neale, D A G Sawtell, Dale A C Brownson, Graham C Smith, P J Kelly, Craig E BanksAbstract:We explore the use of two-dimensional (2D) MoS2 nanosheets as an electrocatalyst for the Hydrogen Evolution Reaction (HER). Using four commonly employed commercially available carbon based electrode support materials, namely edge plane pyrolytic graphite (EPPG), glassy carbon (GC), boron-doped diamond (BDD) and screen-printed graphite Electrodes (SPE), we critically evaluate the reported electrocatalytic performance of unModified and MoS2 Modified Electrodes towards the HER. Surprisingly, current literature focuses almost exclusively on the use of GC as an underlying support electrode upon which HER materials are immobilised. 2D MoS2 nanosheet Modified Electrodes are found to exhibit a coverage dependant electrocatalytic effect towards the HER. Modification of the supporting electrode surface with an optimal mass of 2D MoS2 nanosheets results in a lowering of the HER onset potential by ca. 0.33, 0.57, 0.29 and 0.31 V at EPPG, GC, SPE and BDD Electrodes compared to their unModified counterparts respectively. The lowering of the HER onset potential is associated with each supporting electrode's individual electron transfer kinetics/properties and is thus distinct. The effect of MoS2 coverage is also explored. We reveal that its ability to catalyse the HER is dependent on the mass deposited until a critical mass of 2D MoS2 nanosheets is achieved, after which its electrocatalytic benefits and/or surface stability curtail. The active surface site density and turn over frequency for the 2D MoS2 nanosheets is determined, characterised and found to be dependent on both the coverage of 2D MoS2 nanosheets and the underlying/supporting substrate. This work is essential for those designing, fabricating and consequently electrochemically testing 2D nanosheet materials for the HER.
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exploring the origins of the apparent electrocatalytic oxidation of kojic acid at graphene Modified Electrodes
Analyst, 2013Co-Authors: Luiz C S Figueiredofilho, Dale A C Brownson, Orlando Fatibellofilho, Craig E BanksAbstract:We explore the recent reports that the use of graphene Modified Electrodes gives rise to the electrocatalytic oxidation of kojic acid. It is demonstrated that large quantifiable voltammetric signatures are observed on bare/unModified graphitic Electrodes, which are shown to be analytically useful and superior to those observed at graphene Modified alternatives. This work is of importance as it shows that control experiments are critical and must be undertaken before “electrocatalysis” is conferred when investigating graphene in electrochemistry. In terms of the electroanalytical response of graphene Modified Electrodes, a bare edge plane pyrolytic graphite electrode is shown to give rise to an improved linear range and limit of detection, questioning the need to modify Electrodes with graphene.
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iron oxide particles are the active sites for hydrogen peroxide sensing at multiwalled carbon nanotube Modified Electrodes
Nano Letters, 2006Co-Authors: Biljana Sljukic, Craig E Banks, Richard G. ComptonAbstract:We demonstrate that the “electrocatalytic” hydrogen peroxide detection reported at multiwalled carbon nanotube Modified Electrodes is due to iron oxide particles arising from the chemical vapor deposition nanotube fabrication process rather than due to intrinsic catalysis attributable to the carbon nanotubes arising, for example, from edge plane-like sites/defects.
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electrochemically polymerised composites of multi walled carbon nanotubes and poly vinylferrocene and their use as Modified Electrodes application to glucose sensing
Analyst, 2006Co-Authors: Biljana Sljukic, Craig E Banks, Chris Salter, Alison Crossley, Richard G. ComptonAbstract:We report electrochemical composites of multi-walled carbon nanotubes (MWCNTs) with poly(vinylferrocene) (PVF). The polymeric architecture is prepared by first immobilising the MWCNTs onto a glassy carbon substrate, which acts to introduce electrical current into the composite, with the MWCNTs acting as ‘molecular wires’. PVF films of varying surface coverages can be obtained by simply controlling the time a constant potential of +0.7 V (vs. Ag) wire is applied; with the characteristics of the derivatised MWCNTs examined by cyclic voltammetry and scanning electron microscopy. The application of the composite for glucose determination in aqueous solutions was investigated using linear sweep voltammetry, where it was found that the composites supported on glassy carbon substrates are superior to bare glassy carbon Electrodes polymerised with PVF, likely due to the comparatively higher number of electrocatalytic centres in the former. This protocol was successfully transferred to prepare a PVF-MWCNT-paste electrode which was applied to glucose detection in diluted laked horse blood. The obtained results show potential and promising practical application for the polymer-derivatised MWCNT-Modified Electrodes in amperometric sensors for glucose determination.
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Electrocatalysis at graphite and carbon nanotube Modified Electrodes: Edge-plane sites and tube ends are the reactive sites
Chemical Communications, 2005Co-Authors: Craig E Banks, Trevor J Davies, Gregory G Wildgoose, Richard G. ComptonAbstract:Carbon, and particularly graphite in its various forms, is an attractive electrode material. Two areas of particular interest are Modified carbon Electrodes and carbon nanotube Electrodes. In this article we focus on the relationship between surface structure and electrochemical and chemical reactivity of Electrodes based on these materials. We overview recent work in this area which has led us to believe that much of the catalytic activity, electron transfer and chemical reactivity of graphitic carbon Electrodes is at surface defect sites, and in particular edge-plane-like defect sites. We also question the claimed special "catalytic" properties of carbon nanotube Modified Electrodes.
Jun Wang - One of the best experts on this subject based on the ideXlab platform.
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application of the voltammetric electronic tongue based on nanocomposite Modified Electrodes for identifying rice wines of different geographical origins
Analytica Chimica Acta, 2019Co-Authors: Jun Wang, Weilin Zhang, Luyi Zhu, Zhenbo WeiAbstract:Abstract In the study, the voltammetric electronic tongue based on three nanocomposites Modified Electrodes was applied for the identification of rice wines of different geographical origins. The nanocomposites were prepared by gold and copper nanoparticles in the presence of conducting polymers (polymer sulfanilic acid, polymer glutamic acid) and carboxylic multi - walled carbon nanotubes. The Modified Electrodes showed high sensitivity to guanosine - 5' - monophosphate disodium salt, tyrosine and gallic acid which have good correlation with the geographical origins of rice wines. Scanning electron microscopy was performed to display the surface morphologies of the nanocomposites, and cyclic voltammetry was applied to study the electrochemical behaviors of the taste substances on the electrode surfaces. Four types of electrochemical parameters (pH, scan rates, accumulation potentials and time) were optimized for getting a low limit of the detection of each taste substance. The geographical information of rice wines was obtained by the Modified Electrodes based on two types of multi - frequency large amplitude pulse voltammetry, and “area method” was applied for extracting the feature data from the original information obtained. Based on the area feature data, principal component analysis, locality preserving projection (LPP), and linear discriminant analysis were applied for the classification of the rice wines of different geographical origins, and LPP presented the best results; extreme learning machine (ELM) and alibrary for support vector machines were applied for predicting the geographical origins of rice wines, and ELM performed better.
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application of novel nanocomposite Modified Electrodes for identifying rice wines of different brands
RSC Advances, 2018Co-Authors: Zhenbo Wei, Weilin Zhang, Luyi Zhu, Yanan Yang, Jun WangAbstract:In this paper, poly(acid chrome blue K) (PACBK)/AuNP/glassy carbon electrode (GCE), polysulfanilic acid (PABSA)/AuNP/GCE and polyglutamic acid (PGA)/CuNP/GCE were self-fabricated for the identification of rice wines of different brands. The physical and chemical characterization of the Modified Electrodes were obtained using scanning electron microscopy and cyclic voltammetry, respectively. The rice wine samples were detected by the Modified Electrodes based on multi-frequency large amplitude pulse voltammetry. Chronoamperometry was applied to record the response values, and the feature data correlating with wine brands were extracted from the original responses using the ‘area method’. Principal component analysis, locality preserving projections and linear discriminant analysis were applied for the classification of different wines, and all three methods presented similarly good results. Extreme learning machine (ELM), the library for support vector machines (LIB-SVM) and the backpropagation neural network (BPNN) were applied for predicting wine brands, and BPNN worked best for prediction based on the testing dataset (R2 = 0.9737 and MSE = 0.2673). The fabricated Modified Electrodes can therefore be applied to identify rice wines of different brands with pattern recognition methods, and the application also showed potential for the detection aspects of food quality analysis.
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fabrication of conducting polymer noble metal nanocomposite Modified Electrodes for glucose ascorbic acid and tyrosine detection and its application to identify the marked ages of rice wines
Sensors and Actuators B-chemical, 2018Co-Authors: Zhenbo Wei, Weilin Zhang, Xize Xiao, Yana Yang, Jun WangAbstract:Abstract In previous studies, conductive polymers (CPs)/noble metal nanoparticles (NMNPs) composite materials Modified Electrodes were always applied to distinguish the trace amounts of specific analytes in complex liquid mixtures. In this paper, polymer sulfanilic acid (PABSA)/AuNPs/glassy carbon electrode (GCE), polymer acid chrome blue K (PACBK)/AuNPs/GCE and polymer aspartic acid (PASP)/PtNPs/GCE were fabricated for the identification of the wine age of rice wines with pattern recognitions. The sensitivity of those Modified Electrodes was exhibited by cyclic voltammetry, and the parameters of electrochemical behaviors was optimized and confirmed gradually. The original responses were recorded by chronoamperometry with multi-frequency rectangle pulse voltammetry and multi-frequency staircase pulse voltammetry, and the feature data correlated with the wine age were extracted from original responses by ‘area method’. Based on the feature data, principal component analysis (PCA, unsupervised method), locality preserving projections (LPP, semi-supervised method) and differential financial analysis (DFA, supervised method) were applied for the classification of rice wine samples with different marked age, and DFA exhibited the most clear result; least squares support vector machines (LSSVM) and library for support vector machines (LIBSVM) were applied for the prediction of the wine ages, and LIBSVM worked better than LSSVM, the correlations based on the training and testing dataset were R 2 = 0.9999 and R 2 = 0.9998, respectively. In conclusion, the CPs/NMNPs/GCEs with pattern recognitions were powerful tools to identify the marked ages of rice wines.
Lo Gorton - One of the best experts on this subject based on the ideXlab platform.
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direct electron transfer of phanerochaete chrysosporium cellobiose dehydrogenase at platinum and palladium nanoparticles decorated carbon nanotubes Modified Electrodes
Physical Chemistry Chemical Physics, 2015Co-Authors: Hassan Hamidi, Somayyeh Bozorgzadeh, Roberto Ortiz, Roland Ludwig, Lo GortonAbstract:In the present work, platinum and palladium nanoparticles (PtNPs and PdNPs) were decorated on the surface of multi-walled carbon nanotubes (MWCNTs) by a simple thermal decomposition method. The prepared nanohybrids, PtNPs–MWCNTs and PdNPs–MWCNTs, were cast on the surface of spectrographic graphite Electrodes and then Phanerochaete chrysosporium cellobiose dehydrogenase (PcCDH) was adsorbed on the Modified layer. Direct electron transfer between PcCDH and the nanostructured Modified Electrodes was studied using flow injection amperometry and cyclic voltammetry. The maximum current responses (Imax) and the apparent Michaelis–Menten constants (KappM) for the different PcCDH Modified Electrodes were calculated by fitting the data to the Michaelis–Menten equation and compared. The sensitivity towards lactose was 3.07 and 3.28 μA mM−1 at the PcCDH/PtNPs–MWCNTs/SPGE and PcCDH/PdNPs–MWCNTs/SPGE Electrodes, respectively, which were higher than those measured at the PcCDH/MWCNTs/SPGE (2.60 μA mM−1) and PcCDH/SPGE (0.92 μA mM−1). The Modified Electrodes were additionally tested as bioanodes for biofuel cell applications.
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mediatorless sugar oxygen enzymatic fuel cells based on gold nanoparticle Modified Electrodes
Biosensors and Bioelectronics, 2012Co-Authors: Xiaoju Wang, Lo Gorton, Roberto Ortiz, Roland Ludwig, Magnus Falk, Hirotoshi Matsumura, Johan Bobacka, Mikael Bergelin, Sergey ShleevAbstract:We report on the fabrication and characterisation of a gold-nanoparticle (AuNP)-based mediatorless sugar/oxygen biofuel cell (BFC) operating in neutral sugar-containing buffers and human physiological fluids, such as blood and plasma. First, Corynascus thermophilus cellobiose dehydrogenase (CtCDH) and Myrotheciumverrucaria bilirubin oxidase (MvBOx), used as anodic and cathodic bioelements, respectively, were immobilised on gold Electrodes Modified with 20 nm AuNPs. Detailed characterisation and optimisation of a new CDH/AuNP-based bioanode were performed and the following fundamental parameters were obtained: (i) the redox potential of the haem-containing centre of the enzyme was measured to be 75 mV vs. NHE, (ii) the surface coverage of CtCDH was found to be 0.65 pmol cm(-2) corresponding to a sub-monolayer coverage of the thiol-Modified AuNPs by the enzyme, (iii) a turnover number for CtCDH immobilised on thiol-Modified AuNPs was calculated to be ca. 0.5 s(-1), and (iv) the maximal current densities as high as 40 mu A cm(-2) were registered in sugar-containing neutral buffers. Second, both bioModified Electrodes, namely the CtCDH/AuNP-based bioanode and the MvBOx/AuNP-based biocathode, were combined into a functional BFC and the designed biodevices were carefully investigated. The following characteristics of the mediator-, separator- and membrane-less, miniature BFC were obtained: in phosphate buffer; an open-circuit voltage of 0.68 V, a maximum power density of 15 mu W cm(-2) at a cell voltage of 0.52 V and in human blood; an open-circuit voltage of 0.65 V. a maximum power density of 3 mu W cm(-2) at a cell voltage of 0.45 V, respectively. The estimated half-lives of the biodevices were found to be >12, <8, and <2h in a sugar-containing buffer, human plasma, and blood, respectively. The basic characteristics of mediatorless sugar/oxygen BFCs were significantly improved compared with previously designed biodevices, because of the usage of three-dimensional AuNP-Modified Electrodes. (C) 2011 Elsevier B.V. All rights reserved. (Less)
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electrocatalytic oxidation of nad p h at mediator Modified Electrodes
Reviews in Molecular Biotechnology, 2002Co-Authors: Lo Gorton, Elena DominguezAbstract:A review is presented dealing with electrocatalytic NADH oxidation at mediator-Modified Electrodes, summarising the history of the topic, as well as the present state of the art.
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peroxidase Modified Electrodes fundamentals and application
Analytica Chimica Acta, 1996Co-Authors: Tautgirdas Ruzgas, Lo Gorton, Elisabeth Csoregi, Jenny Emneus, Gyorgy MarkovargaAbstract:Peroxidase-Modified amperometric Electrodes have been widely studied and developed, not only because of hydrogen- and organic peroxides are important analytes but also because of the key role of hydrogen peroxide detection in coupled enzyme systems, in which hydrogen peroxide is formed as the product of the enzymatic reaction. Many important analytes, such as, aromatic amines, phenolic compounds, glucose, lactate, neurotransmitters, etc. could be monitored by using bi- or multi-enzyme Electrodes. In this review the heterogeneous electron transfer properties of peroxidases are discussed as a basis for the analytical application of the peroxidase-Modified amperometric Electrodes, and examples are given for various peroxidase electrode designs and their application.
Gregory G Wildgoose - One of the best experts on this subject based on the ideXlab platform.
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using multiwalled carbon nanotube Modified Electrodes for the adsorptive striping voltammetric determination of hesperidin
Electrochimica Acta, 2009Co-Authors: Marcus J Sims, Gregory G Wildgoose, Roohollah Torabi Kachoosangi, Richard G. ComptonAbstract:Abstract Hesperidin, a flavone glycoside found in the skins and juices of citrus fruits, can be detected using multiwalled carbon nanotube (MWCNT)-Modified Electrodes using the technique of adsorptive stripping voltammetry (AdSV) with accumulation at open circuit potential. This is relevant because hesperidin can be used as an indication of the citrus fruit juice's freshness. The oxidation mechanism to explain the observed voltammetry corresponds to the redox chemistry of the guaiacol sub-unit within the hesperidin molecular structure. Hesperidin could be detected over a linear range up to 30 μM, and with a detection limit of 0.61 μM and 7 nM, with less than 5% variation between different Electrodes, using cyclic voltammetric or square wave adsorptive stripping techniques respectively. This methodology was extended to MWCNT-Modified screen-printed Electrodes (MWCNT-SPEs), allowing the development of a cheap, mass produced, disposable sensor that we show is capable of measuring the concentration of hesperidin in real orange juice samples, and be applied within the citrus fruit industry.
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exploring the origins of the apparent electrocatalysis observed at c60 film Modified Electrodes
Sensors and Actuators B-chemical, 2009Co-Authors: Lei Xiao, Gregory G Wildgoose, Richard G. ComptonAbstract:We have recently revised the oft-cited model of cation insertion into electroreduced C60 film-Modified Electrodes in aqueous, basic electrolytes [L. Xiao, G.G. Wildgoose, A. Crossley, R.G. Compton, The electroreduction of “C60” films in aqueous electrolyte does not lead to alkali metal ion insertion—evidence for the involvement of adventitious poly-epoxidated C60 (C60On), submitted for publication]. Instead we have proposed that the observed reduction corresponds to adventitious polyepoxidated C60On within the starting material [L. Xiao, G.G. Wildgoose, A. Crossley, R.G. Compton, The electroreduction of “C60” films in aqueous electrolyte does not lead to alkali metal ion insertion—evidence for the involvement of adventitious poly-epoxidated C60 (C60On), submitted for publication]. In this paper, we further show, using scanning electron microscopy and cyclic voltammetry of ascorbic acid, how our alternative model can be used to explain both the voltammetric behaviour observed during the reduction of “C60” films in aqueous electrolytes, and how the structure of these films can give rise to misleading claims of apparent “electrocatalytic” behaviour. The latter arises due to restructuring of the deposited C60 film giving rise to a porous, partially blocked electrode, coupled with possible thin-layer effects. We find no evidence that C60 itself is reduced within the potential window offered by aqueous electrolytes, nor that it is involved in any form of electron mediation or electrocatalysis.
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cyclic voltammetry on electrode surfaces covered with porous layers an analysis of electron transfer kinetics at single walled carbon nanotube Modified Electrodes
Sensors and Actuators B-chemical, 2008Co-Authors: Ian Streeter, Gregory G Wildgoose, Lidong Shao, Richard G. ComptonAbstract:Cyclic voltammetry is recorded of the oxidation of ferrocyanide on a glassy carbon electrode Modified with multiple layers of single-walled carbon nanotubes. The current response is interpreted in terms of semi-infinite planar diffusion towards the macro-electrode surface and in terms of oxidation of the electroactive species trapped in pockets in between the nanotubes. A thin layer model is used to illustrate the effects of diffusion within a porous layer. It is found that a semi-infinite planar diffusion model alone is not appropriate for interpreting the kinetics of the electron transfer at this electrode surface. In particular, caution should be exercised in respect of comparing voltammetric peak-to-peak potential separations between naked Electrodes and nanotube-Modified Electrodes for the inference of electrocatalysis via electron transfer via the nanotubes.
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Electrocatalysis at graphite and carbon nanotube Modified Electrodes: Edge-plane sites and tube ends are the reactive sites
Chemical Communications, 2005Co-Authors: Craig E Banks, Trevor J Davies, Gregory G Wildgoose, Richard G. ComptonAbstract:Carbon, and particularly graphite in its various forms, is an attractive electrode material. Two areas of particular interest are Modified carbon Electrodes and carbon nanotube Electrodes. In this article we focus on the relationship between surface structure and electrochemical and chemical reactivity of Electrodes based on these materials. We overview recent work in this area which has led us to believe that much of the catalytic activity, electron transfer and chemical reactivity of graphitic carbon Electrodes is at surface defect sites, and in particular edge-plane-like defect sites. We also question the claimed special "catalytic" properties of carbon nanotube Modified Electrodes.