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Malel E, Mandler D. Biocatalytic metal nanopatterning through enzyme-modified microelectrodes. J Solid State Electrochem 2020. [DOI: 10.1007/s10008-020-04730-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Strutwolf J, Zhang J, Unwin PR. Investigation of Molecular Transfer Processes across Phospholipid Monolayers by the Combined Scanning Electrochemical Microscopy-Langmuir Trough Technique. PROGRESS IN REACTION KINETICS AND MECHANISM 2019. [DOI: 10.3184/1468607x247749] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Scanning electrochemical microscopy (SECM) has emerged as a powerful techniquefor inducing and monitoring molecular transfer processes across water/air and liquid/liquid interfaces. At the same time, the Langmuir trough technique is a well established method for controlling the lateral pressure of molecular films of amphiphilic molecules at interfaces. A combination of both methods allows the investigation of the permeability of monolayers in a defined state. A brief introduction of the SECM technique and the experimental set-up is presented. The application of the combined SECM- Langmuir trough technique to measure passive diffusion of small molecules (O2 and Br2) across phospholipid monolayers is then reviewed. Phospholipid monolayers at liquid/liquid and liquid/air interfaces serve as simple biomimetic models for biomembranes and the results of the combined SECM- Langmuir trough measurements have implications for understanding passive diffusion across cellular membranes.
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Affiliation(s)
- Jörg Strutwolf
- Tyndall National Institute, Lee Maltings, University College Cork, Cork, Ireland and University of Tübingen, Department of Chemistry, Institute of Organic Chemistry, Auf der Morgenstelle 18, 72076 Tübingen, Germany
| | - Jie Zhang
- Institute of Bioengineering and Nanotechnology, 31 Biopolis Way, The Nanos, #04-01, Singapore 138669
| | - Patrick R. Unwin
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, UK
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Rong Y, He D, Sanchez-Fernandez A, Evans C, Edler KJ, Malpass-Evans R, Carta M, McKeown NB, Clarke TJ, Taylor SH, Wain AJ, Mitchels JM, Marken F. Intrinsically Microporous Polymer Retains Porosity in Vacuum Thermolysis to Electroactive Heterocarbon. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:12300-12306. [PMID: 26496244 DOI: 10.1021/acs.langmuir.5b02654] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Vacuum carbonization of organic precursors usually causes considerable structural damage and collapse of morphological features. However, for a polymer with intrinsic microporosity (PIM-EA-TB with a Brunauer-Emmet-Teller (BET) surface area of 1027 m(2)g(-1)), it is shown here that the rigidity of the molecular backbone is retained even during 500 °C vacuum carbonization, yielding a novel type of microporous heterocarbon (either as powder or as thin film membrane) with properties between those of a conducting polymer and those of a carbon. After carbonization, the scanning electron microscopy (SEM) morphology and the small-angle X-ray scattering (SAXS) Guinier radius remain largely unchanged as does the cumulative pore volume. However, the BET surface area is decreased to 242 m(2)g(-1), but microporosity is considerably increased. The new material is shown to exhibit noticeable electrochemical features including two pH-dependent capacitance domains switching from ca. 33 Fg(-1) (when oxidized) to ca. 147 Fg(-1) (when reduced), a low electron transfer reactivity toward oxygen and hydrogen peroxide, and a four-point-probe resistivity (dry) of approximately 40 MΩ/square for a 1-2 μm thick film.
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Affiliation(s)
- Yuanyang Rong
- Department of Chemistry, University of Bath , Claverton Down, Bath BA2 7AY, United Kingdom
| | - Daping He
- Department of Chemistry, University of Bath , Claverton Down, Bath BA2 7AY, United Kingdom
| | | | - Craig Evans
- Department of Chemistry, University of Bath , Claverton Down, Bath BA2 7AY, United Kingdom
| | - Karen J Edler
- Department of Chemistry, University of Bath , Claverton Down, Bath BA2 7AY, United Kingdom
| | - Richard Malpass-Evans
- School of Chemistry, University of Edinburgh , West Mains Road, Edinburgh, EH9 3JJ, United Kingdom
| | - Mariolino Carta
- School of Chemistry, University of Edinburgh , West Mains Road, Edinburgh, EH9 3JJ, United Kingdom
| | - Neil B McKeown
- School of Chemistry, University of Edinburgh , West Mains Road, Edinburgh, EH9 3JJ, United Kingdom
| | - Tomos J Clarke
- School of Chemistry, Cardiff University , Main Building, Park Place, Cardiff CF10 3AT, United Kingdom
| | - Stuart H Taylor
- School of Chemistry, Cardiff University , Main Building, Park Place, Cardiff CF10 3AT, United Kingdom
| | - Andrew J Wain
- National Physical Laboratory , Teddington, TW11 0LW, United Kingdom
| | - John M Mitchels
- Department of Chemistry, University of Bath , Claverton Down, Bath BA2 7AY, United Kingdom
| | - Frank Marken
- Department of Chemistry, University of Bath , Claverton Down, Bath BA2 7AY, United Kingdom
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Coates M, Nyokong T. Characterization of glassy carbon electrodes modified with carbon nanotubes and iron phthalocyanine through grafting and click chemistry. Electrochim Acta 2013. [DOI: 10.1016/j.electacta.2012.12.112] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Izquierdo J, Nagy L, Bitter I, Souto RM, Nagy G. Potentiometric scanning electrochemical microscopy for the local characterization of the electrochemical behaviour of magnesium-based materials. Electrochim Acta 2013. [DOI: 10.1016/j.electacta.2012.09.029] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Izquierdo J, Nagy L, Varga Á, Bitter I, Nagy G, Souto RM. Scanning electrochemical microscopy for the investigation of corrosion processes: Measurement of Zn2+ spatial distribution with ion selective microelectrodes. Electrochim Acta 2012. [DOI: 10.1016/j.electacta.2011.10.076] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Malel E, Ludwig R, Gorton L, Mandler D. Localized Deposition of Au Nanoparticles by Direct Electron Transfer through Cellobiose Dehydrogenase. Chemistry 2010; 16:11697-706. [DOI: 10.1002/chem.201000453] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2010] [Revised: 06/14/2010] [Indexed: 11/06/2022]
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French RW, Chan Y, Bulman-Page PC, Marken F. Liquid-liquid ion transport junctions based on paired gold electrodes in generator-collector mode. Electrophoresis 2009; 30:3361-5. [DOI: 10.1002/elps.200900083] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Pust SE, Maier W, Wittstock G. Investigation of Localized Catalytic and Electrocatalytic Processes and Corrosion Reactions with Scanning Electrochemical Microscopy (SECM). ACTA ACUST UNITED AC 2009. [DOI: 10.1524/zpch.2008.5426] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
AbstractScanning electrochemical microscopy (SECM) has developed into a very versatile tool for the investigation of solid-liquid, liquid-liquid and liquid-gas interfaces. The arrangement of an ultramicroelectrode (UME) in close proximity to the interface under study allows the application of a large variety of different experimental schemes. The most important have been named feedback mode, generation-collection mode, redox competition mode and direct mode. Quantitative descriptions are available for the UME signal, depending on different sample properties and experimental variables. Therefore, SECM has been established as an indispensible tool in many areas of fundamental electrochemical research. Currently, it also spreads as an important new method to solve more applied problems, in which inhomogeneous current distributions are typically observed on different length scales. Prominent examples include devices for electrochemical energy conversion such as fuel cells and batteries as well as localized corrosion phenomena. However, the direct local investigation of such systems is often impossible. Instead, suitable reaction schemes, sample environments, model samples and even new operation modes have to be introduced in order to obtain results that are relevant to the practical application. This review outlines and compares the theoretical basis of the different SECM working modes and reviews the application in the area of electrochemical energy conversion and localized corrosion with a special emphasis on the problems encountered when working with practical samples.
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Csoka B, Mekhalif Z. Carbon paste-based ion-selective dual function microelectrodes for SECM measurements. Electrochim Acta 2009. [DOI: 10.1016/j.electacta.2008.10.067] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Surface Analytical Methods. SURF INTERFACE ANAL 2009. [DOI: 10.1007/978-3-540-49829-2_7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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French R, Collins A, Marken F. Growth and Application of Paired Gold Electrode Junctions: Evidence for Nitrosonium Phosphate During Nitric Oxide Oxidation. ELECTROANAL 2008. [DOI: 10.1002/elan.200804354] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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French RW, Marken F. Growth and characterisation of diffusion junctions between paired gold electrodes: diffusion effects in generator–collector mode. J Solid State Electrochem 2008. [DOI: 10.1007/s10008-008-0698-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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dos Santos Riccardi C, Kranz C, Kowalik J, Yamanaka H, Mizaikoff B, Josowicz M. Label-free DNA detection of hepatitis C virus based on modified conducting polypyrrole films at microelectrodes and atomic force microscopy tip-integrated electrodes. Anal Chem 2007; 80:237-45. [PMID: 18034460 DOI: 10.1021/ac701613t] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
We present a new strategy for the label-free electrochemical detection of DNA hybridization for detecting hepatitis C virus based on electrostatic modulation of the ion-exchange kinetics of a polypyrrole film deposited at microelectrodes. Synthetic single-stranded 18-mer HCV genotype-1-specific probe DNA has been immobilized at a 2,5-bis(2-thienyl)-N-(3-phosphoryl-n-alkyl)pyrrole film established by electropolymerization at the previously formed polypyrrole layer. HCV DNA sequences (244-mer) resulting from the reverse transcriptase-linked polymerase chain reaction amplification of the original viral RNA were monitored by affecting the ion-exchange properties of the polypyrrole film. The performance of this miniaturized DNA sensor system was studied in respect to selectivity, sensitivity, and reproducibility. The limit of detection was determined at 1.82x10(-21) mol L(-1). Control experiments were performed with cDNA from HCV genotypes 2a/c, 2b, and 3 and did not show any unspecific binding. Additionally, the influence of the spacer length of 2,5-bis(2-thienyl)-N-(3-phosphoryl-n-alkyl)pyrrole on the behavior of the DNA sensor was investigated. This biosensing scheme was finally extended to the electrochemical detection of DNA at submicrometer-sized DNA biosensors integrated into bifunctional atomic force scanning electrochemical microscopy probes. The 18-mer DNA target was again monitored by following the ion-exchange properties of the polypyrrole film. Control experiments were performed with 12-base pair mismatched sequences.
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Affiliation(s)
- Carla dos Santos Riccardi
- School of Chemistry and Biochemistry, Georgia Institute of Technology, 901 Atlantic Dr, Atlanta, Georgia 30332-0400, USA
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Szunerits S, Pust SE, Wittstock G. Multidimensional electrochemical imaging in materials science. Anal Bioanal Chem 2007; 389:1103-20. [PMID: 17602213 DOI: 10.1007/s00216-007-1374-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2007] [Revised: 05/08/2007] [Accepted: 05/10/2007] [Indexed: 11/28/2022]
Abstract
In the past 20 years the characterization of electroactive surfaces and electrode reactions by scanning probe techniques has advanced significantly, benefiting from instrumental and methodological developments in the field. Electrochemical and electrical analysis instruments are attractive tools for identifying regions of different electrochemical properties and chemical reactivity and contribute to the advancement of molecular electronics. Besides their function as a surface analytical device, they have proved to be unique tools for local synthesis of polymers, metal depots, clusters, etc. This review will focus primarily on progress made by use of scanning electrochemical microscopy (SECM), conductive AFM (C-AFM), electrochemical scanning tunneling microscopy (EC-STM), and surface potential measurements, for example Kelvin probe force microscopy (KFM), for multidimensional imaging of potential-dependent processes on metals and electrified surfaces modified with polymers and self assembled monolayers.
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Affiliation(s)
- Sabine Szunerits
- Laboratoire d'Electrochimie et de Physicochimie des Matériaux et des Interfaces (LEPMI), CNRS-INPG-UJF, St Martin d'Hères Cedex, France.
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Cornut R, Lefrou C. New analytical approximations for negative feedback currents with a microdisk SECM tip. J Electroanal Chem (Lausanne) 2007. [DOI: 10.1016/j.jelechem.2007.02.029] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Wittstock G, Burchardt M, Pust SE, Shen Y, Zhao C. Scanning electrochemical microscopy for direct imaging of reaction rates. Angew Chem Int Ed Engl 2007; 46:1584-617. [PMID: 17285666 DOI: 10.1002/anie.200602750] [Citation(s) in RCA: 313] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Not only in electrochemistry but also in biology and in membrane transport, localized processes at solid-liquid or liquid-liquid interfaces play an important role at defect sites, pores, or individual cells, but are difficult to characterize by integral investigation. Scanning electrochemical microscopy is suitable for such investigations. After two decades of development, this method is based on a solid theoretical foundation and a large number of demonstrated applications. It offers the possibility of directly imaging heterogeneous reaction rates and locally modifying substrates by electrochemically generated reagents. The applications range from classical electrochemical problems, such as the investigation of localized corrosion and electrocatalytic reactions in fuel cells, sensor surfaces, biochips, and microstructured analysis systems, to mass transport through synthetic membranes, skin and tissue, as well as intercellular communication processes. Moreover, processes can be studied that occur at liquid surfaces and liquid-liquid interfaces.
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Affiliation(s)
- Gunther Wittstock
- Carl von Ossietzky Universität Oldenburg, Institut für Reine und Angewandte Chemie und Institut für Chemie und Biologie des Meeres, 26111 Oldenburg, Germany.
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Gyetvai G, Sundblom S, Nagy L, Ivaska A, Nagy G. Solid Contact Micropipette Ion Selective Electrode for Potentiometric SECM. ELECTROANAL 2007. [DOI: 10.1002/elan.200703831] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Malik MA, Kulesza PJ. Monitoring of Conductivity Changes in Passive Layers by Scanning Electrochemical Microscopy in Feedback Mode: Localization of Pitting Precursor Sites on Surfaces of Multimetallic Phase Materials. Anal Chem 2007; 79:3996-4005. [PMID: 17465528 DOI: 10.1021/ac061664f] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Scanning electrochemical microscopy (SECM) in feedback mode was applied to monitor changes in the electronic conductivity of a passive layer existing on a nanocrystalline Nd-Fe-B-type permanent magnet of the following composition, Nd13.5Fe79.5Si1B6 (where subscripts denote at. %). This model magnet being a complex multimetallic-phase material (fabricated according to the hydrogenation-disproportionation-desorption-recombination route) contained intrinsic iron inclusions, as evident from SEM and EDX mapping. SECM measurements performed in feedback mode using ferrocenecarboxylic acid as a mediator (in phosphate buffer at pH 7) in the presence and absence of chloride anions permitted evaluation of the local surface (passive layer) conductivity changes during pitting corrosion caused by Cl- anions. The spots of high conductivity (electronic or redox) act as precursor sites for initiation of pits. It can be rationalized that iron inclusions are responsible for the high susceptibility of Nd-Fe-B magnets to pitting corrosion. The approach is fairly general and allows localization of pitting precursor sites under different corrosion environments that include a wide range of concentrations of anions causing the passive layer breakdown.
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Affiliation(s)
- Marcin A Malik
- Division of Chemistry, Department of Materials Processing Technology and Applied Physics, Czestochowa University of Technology, Al. Armii Krajowej 19, 42-201 Czestochowa, Poland.
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Wittstock G, Burchardt M, Pust S, Shen Y, Zhao C. Elektrochemische Rastermikroskopie zur direkten Abbildung von Reaktionsgeschwindigkeiten. Angew Chem Int Ed Engl 2007. [DOI: 10.1002/ange.200602750] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Wang K, He FY, Liu AL, Xu JJ, Chen HY, Xia XH. Novel coupling mechanism-based imaging approach to scanning electrochemical microscopy for probing the electric field distribution at the microchannel end. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2006; 22:7052-8. [PMID: 16863259 DOI: 10.1021/la0601049] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
A novel coupling mechanism-based imaging approach to scanning electrochemical microscopy (SECM) was used to image the distribution of electric field at the end channel of a poly(dimethylsiloxane) (PDMS) capillary electrophoresis (CE) microchip in the absence of redox species. The coupling imaging mechanism was systematically investigated and qualitatively illustrated. It was proved that the distribution of solution potentials within the scanning plane caused a different reduction rate of water at the tip electrode, which led to the variation in tip current. Within the scanning plane, the solution potentials measured in the central area of the microchannel were usually higher than those measured outside. The SECM images showed a strong dependence on tip potential, tip-to-channel distance, and separation potential. According to the Tafel equation, SECM images were converted to parameters that directly showed the distribution of solution potential. Change in the solution potential along the central axial line of the microchannel was also continuously sensed by allowing the tip to approach the microchannel in the presence of high voltage. Using dopamine as a model compound, the effect of solution potential on electrochemical detection was estimated by detecting separation parameters.
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Affiliation(s)
- Kang Wang
- Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China
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O'Mullane AP, Neufeld AK, Bond AM. Distinction of the Two Phases of CuTCNQ by Scanning Electrochemical Microscopy. Anal Chem 2005; 77:5447-52. [PMID: 16131051 DOI: 10.1021/ac050172k] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The two known phases of CuTCNQ and TCNQ (TCNQ = 7,7',8,8'-tetracyanoquinodimethane) have been probed by scanning electrochemical microscopy (SECM) in the feedback mode. The first use of this technique for distinguishing differences in the electronic properties of semiconductor phases exploits the large differences in conductivity that exist between CuTCNQ and the parent TCNQ material and also between the CuTCNQ phases I and II. However, the packing density of the individual CuTCNQ crystals in a film structure also is shown to influence the SECM feedback response. Finally, it is shown that films of pure phase II material or mixtures of the phases can be mapped using feedback mode SECM. The SECM method provides valuable insights for elucidating properties of semiconducting solids that are mounted on insulating substrates.
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Bastos A, Simões A, González S, González-García Y, Souto R. Imaging concentration profiles of redox-active species in open-circuit corrosion processes with the scanning electrochemical microscope. Electrochem commun 2004. [DOI: 10.1016/j.elecom.2004.09.022] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
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Csóka B, Nagy G. Determination of diffusion coefficient in gel and in aqueous solutions using scanning electrochemical microscopy. ACTA ACUST UNITED AC 2004; 61:57-67. [PMID: 15560922 DOI: 10.1016/j.jbbm.2004.03.001] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2003] [Revised: 03/01/2004] [Accepted: 03/01/2004] [Indexed: 10/26/2022]
Abstract
Diffusion coefficient of different species in different media is an important property needed in scientific research and practice. A method taking advantage on the special capability of scanning electrochemical microscopy (SECM) is described for the easy and accurate measurement of diffusion coefficient. The method is based on detecting the concentration-time transients with appropriate electrochemical microsensor positioned at the close vicinity of a miniature dose-source device. At a given time (ti), a small dose of the investigated species is introduced. The Deltatmax=(tcmax-ti) value and the distance (d=x+Deltaxn) between the source and the detector microelectrode are used for the calculation of D. While the original set distance (x) cannot be accurately measured in the micrometer scale, the tip travel distance (Deltaxn) of the microscope is well defined. Collecting a few Deltatmax-(x+Deltaxn) data pairs, a reliable value of the diffusion coefficient can be obtained. The procedure is simple, and no exact knowledge of the introduced dose is needed. Two ways of sample dose delivery were used: on the one hand, coulometric generation with current-controlled electric pulse using micro-disc electrode, and on the other one, pressure ejection of a nano-droplet from a glass micropipette. Diffusion coefficient of I2, H2O2, [Ru(NH3)6]Cl3 and K3[Fe(CN)6] were measured in solution and in agarose gel phases of different composition. The effect of polyelectrolyte ion exchangers on the diffusion of the investigated species was checked.
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Affiliation(s)
- Balázs Csóka
- MTA-PTE Research Group for Chemical Sensors, Ifjúság útja 6., H-7624 Pécs, Hungary
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Etienne M, Schulte A, Mann S, Jordan G, Dietzel ID, Schuhmann W. Constant-Distance Mode Scanning Potentiometry. 1. Visualization of Calcium Carbonate Dissolution in Aqueous Solution. Anal Chem 2004; 76:3682-8. [PMID: 15228341 DOI: 10.1021/ac0349227] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Constant-distance mode scanning potentiometry was established by integrating potentiometric microsensors as ion-selective scanning probes into a SECM setup that was equipped with a piezoelectric shear force-based tip-to-sample distance control. The combination of specially designed micrometer-sized potentiometric tips with an advanced system for tip positioning allowed simultaneous acquisition of both topographic and potentiometric information at solid/liquid interfaces with high spatial resolution. The performance of the approach was evaluated by applying Ca(2+)-selective constant-distance mode potentiometry to monitor the dissolution of calcium carbonate occurring either at the (104) surface of calcite crystals or in proximity to the more complex surface of cross sections of a calcium carbonate shell of Mya arenaria exposed to slightly acidic aqueous solutions. Micrometer-scale heterogeneities in the apparent calcium activity profiles have successfully been resolved for both samples.
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Affiliation(s)
- Mathieu Etienne
- Analytische Chemie-Elektroanalytik & Sensorik, Lehrstuhl für Molekulare Neurobiochemie, Ruhr-Universität Bochum, D-44780 Bochum, Germany
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Etienne M, Schulte A, Schuhmann W. High resolution constant-distance mode alternating current scanning electrochemical microscopy (AC-SECM). Electrochem commun 2004. [DOI: 10.1016/j.elecom.2004.01.006] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
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Allard D, Allard S, Brehmer M, Conrad L, Zentel R, Stromberg C, Schultze J. Micro- and nanostructuring of oligo- and polythiophenes in two and three dimensions. Electrochim Acta 2003. [DOI: 10.1016/s0013-4686(03)00343-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Turyan I, Orel B, Reisfeld R, Mandler D. Studying electron transfer at electrochromic tungsten oxide sol–gel films with scanning electrochemical microscopy (SECM). Phys Chem Chem Phys 2003. [DOI: 10.1039/b301380d] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Spaine TW, Baur JE. A positionable microcell for electrochemistry and scanning electrochemical microscopy in subnanoliter volumes. Anal Chem 2001; 73:930-8. [PMID: 11289438 DOI: 10.1021/ac0011787] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
Positionable voltammetric cells with tip diameters of < 50 microm were constructed from theta glass capillaries. One channel of the pulled glass capillary contains a carbon fiber microelectrode sealed in epoxy while the other houses a Ag/AgCl reference electrode that makes electrical contact to the analyte solution via a salt bridge at the tip. The device can be operated as a two-electrode cell and can therefore make measurements in droplets of solution that are similar in size to the tip. Alternatively, if the droplet of solution is larger than the tip, spatially resolved measurements of a substrate in solution can be made. Voltammetric experiments and feedback imaging with the scanning electrochemical microscope (SECM) were accomplished in microdroplets with solution volumes of less than 1 nL. pH images of a substrate immersed in 70-microL-thick films of solution were obtained in the generator-collector mode of SECM using an iridium oxide-modified microcell. This type of microcell is particularly useful for making electrochemical measurements in very small droplets of solution where a mobile working electrode could easily collide with a separately positioned reference electrode.
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Affiliation(s)
- T W Spaine
- Department of Chemistry, Illinois State University, Normal 61790-4160, USA
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