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Bird MJ, Pearson MA, Asaoka S, Miller JR. General Method for Determining Redox Potentials without Electrolyte. J Phys Chem A 2020; 124:5487-5495. [PMID: 32437607 DOI: 10.1021/acs.jpca.0c02948] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A novel method to determine redox potentials without electrolyte is presented. The method is based on a new ability to determine the dissociation constant, K°d, for ion pairs formed between any radical anion and any inert electrolyte counterion. These dissociation constants can be used to determine relative shifts of redox potential as a function of electrolyte concentration, connecting referenced potentials determined with electrochemistry (with 0.1 M electrolyte) to electrolyte-free values. Pulse radiolysis created radical anions enabling determination of equilibrium constants for electron transfer between anions of donor and acceptor molecules as a function of electrolyte concentration in THF. The measurements determined "composite equilibrium constants", KeqC, which contain information about the dissociation constant for the electrolyte cations, X+, with the radical anions of both the donor, K°d(D-•,X+) and the acceptor, K°d(A-•,X+). Dissociation constants were obtained for a selection of radical anions with tetrabutylammonium (TBA+). The electrolyte was found to shift the reduction potentials of small molecules 1-methylpyrene and trans-stilbene by close to +130 mV whereas oligo-fluorenes and polyfluorenes experienced shifts of only (+25 ± 6) mV due to charge delocalization weakening the ion pair. These shifts for reduction of aromatic hydrocarbon molecules are smaller than shifts of +232 and +451 mV seen previously for benzophenone radical anion with TBA+ and Na+ respectively where the charge on the radical anion is localized largely on one C═O bond, thus forming a more tightly bound ion pair.
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Affiliation(s)
- Matthew J Bird
- Chemistry Department, Brookhaven National Laboratory, Upton, New York 11793-5000, United States
| | - Matthew A Pearson
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Sadayuki Asaoka
- Department of Biomolecular Engineering, Kyoto Institute of Technology, Matsugaskaki, Sakyo-ku, Kyoto 606-8585, Japan
| | - John R Miller
- Chemistry Department, Brookhaven National Laboratory, Upton, New York 11793-5000, United States
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Glasscott MW, Dick JE. Fine-Tuning Porosity and Time-Resolved Observation of the Nucleation and Growth of Single Platinum Nanoparticles. ACS NANO 2019; 13:4572-4581. [PMID: 30790511 DOI: 10.1021/acsnano.9b00546] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Porous metal nanoparticles (NPs) are important to a variety of applications; however, robust control over NP porosity is difficult to achieve. Here, we demonstrate control over NP porosity using nanodroplet-mediated electrodeposition by introducing glycerol into water droplets. Porosity approached 0 under viscous conditions (>6 cP), and intermediate viscosities allowed the fine-tuning of NP porosity between 0 and 15%. This method also allowed for control over average pore radius (1 to 5 nm) and pore density (2 to 6 × 1015 pores per square meter). Reduced mass transfer within water droplets was validated by studying single chloroplatinate-filled water droplet (droplet radius of ∼450 nm) collisions on a platinum ultramicroelectrode (UME, rUME = 5 μm). Collision transient lifetimes in the i- t response increased with increasing viscosity, and the total charge per event was conserved. The change in shape was consistent with the nucleation and growth of a platinum NP within the droplet, which was confirmed by fitting transients to classical nucleation and growth theory for single centers as a function of over-potential. This analysis allowed electrokinetic growth and diffusion-controlled growth to be distinguished and semi-quantified at the single NP level.
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Affiliation(s)
- Matthew W Glasscott
- Department of Chemistry , The University of North Carolina at Chapel Hill , Chapel Hill , North Carolina 27599 , United States
| | - Jeffrey E Dick
- Department of Chemistry , The University of North Carolina at Chapel Hill , Chapel Hill , North Carolina 27599 , United States
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Wang Y, Shan X, Tao N. Emerging tools for studying single entity electrochemistry. Faraday Discuss 2018; 193:9-39. [PMID: 27722354 DOI: 10.1039/c6fd00180g] [Citation(s) in RCA: 69] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Electrochemistry studies charge transfer and related processes at various microscopic structures (atomic steps, islands, pits and kinks on electrodes), and mesoscopic materials (nanoparticles, nanowires, viruses, vesicles and cells) made by nature and humans, involving ions and molecules. The traditional approach measures averaged electrochemical quantities of a large ensemble of these individual entities, including the microstructures, mesoscopic materials, ions and molecules. There is a need to develop tools to study single entities because a real system is usually heterogeneous, e.g., containing nanoparticles with different sizes and shapes. Even in the case of "homogeneous" molecules, they bind to different microscopic structures of an electrode, assume different conformations and fluctuate over time, leading to heterogeneous reactions. Here we highlight some emerging tools for studying single entity electrochemistry, discuss their strengths and weaknesses, and provide personal views on the need for tools with new capabilities for further advancing single entity electrochemistry.
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Affiliation(s)
- Yixian Wang
- Center for Biosensors and Bioelectronics, Biodesign Institute and School of Electrical, Computer and Energy Engineering, Arizona State University, Tempe, Arizona 85287, USA.
| | - Xiaonan Shan
- Center for Biosensors and Bioelectronics, Biodesign Institute and School of Electrical, Computer and Energy Engineering, Arizona State University, Tempe, Arizona 85287, USA.
| | - Nongjian Tao
- Center for Biosensors and Bioelectronics, Biodesign Institute and School of Electrical, Computer and Energy Engineering, Arizona State University, Tempe, Arizona 85287, USA. and State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China
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Bird MJ, Iyoda T, Bonura N, Bakalis J, Ledbetter AJ, Miller JR. Effects of electrolytes on redox potentials through ion pairing. J Electroanal Chem (Lausanne) 2017. [DOI: 10.1016/j.jelechem.2017.09.030] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Kundys M, Nejbauer M, Jönsson-Niedziolka M, Adamiak W. Generation–Collection Electrochemistry Inside a Rotating Droplet. Anal Chem 2017; 89:8057-8063. [DOI: 10.1021/acs.analchem.7b01533] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Magdalena Kundys
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland
| | - Michal Nejbauer
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland
| | | | - Wojciech Adamiak
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland
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He D, Madrid E, Aaronson BDB, Fan L, Doughty J, Mathwig K, Bond AM, McKeown NB, Marken F. A Cationic Diode Based on Asymmetric Nafion Film Deposits. ACS APPLIED MATERIALS & INTERFACES 2017; 9:11272-11278. [PMID: 28287696 DOI: 10.1021/acsami.7b01774] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
A thin film of Nafion, of approximately 5 μm thickness, asymmetrically deposited onto a 6 μm thick film of poly(ethylene terephthalate) (PET) fabricated with a 5, 10, 20, or 40 μm microhole, is shown to exhibit prominent ionic diode behavior involving cation charge carrier ("cationic diode"). The phenomenon is characterized via voltammetric, chronoamperometric, and impedance methods. Phenomenologically, current rectification effects are comparable to those observed in nanocone devices where space-charge layer effects dominate. However, for microhole diodes a resistive, a limiting, and an overlimiting potential domain can be identified and concentration polarization in solution is shown to dominate in the closed state.
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Affiliation(s)
- Daping He
- Department of Chemistry, University of Bath , Claverton Down, Bath BA2 7AY, U.K
| | - Elena Madrid
- Department of Chemistry, University of Bath , Claverton Down, Bath BA2 7AY, U.K
| | - Barak D B Aaronson
- Department of Chemistry, University of Bath , Claverton Down, Bath BA2 7AY, U.K
| | - Lian Fan
- Department of Biology and Biochemistry, University of Bath , Claverton Down, Bath BA2 7AY, U.K
| | - James Doughty
- Department of Biology and Biochemistry, University of Bath , Claverton Down, Bath BA2 7AY, U.K
| | - Klaus Mathwig
- Pharmaceutical Analysis, Groningen Research Institute of Pharmacy, University of Groningen , P.O. Box 196, 9700 AD Groningen, The Netherlands
| | - Alan M Bond
- Monash University , School of Chemistry, Clayton, Vic 3800, Australia
| | - Neil B McKeown
- EastChem School of Chemistry, University of Edinburgh , David Brewster Road, Edinburgh, EH9 3FJ, U.K
| | - Frank Marken
- Department of Chemistry, University of Bath , Claverton Down, Bath BA2 7AY, U.K
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Aoki KJ. Voltammetry at a single nano-electrode by varying electrode diameters: Review. J Electroanal Chem (Lausanne) 2016. [DOI: 10.1016/j.jelechem.2016.03.029] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Ma C, Xu W, Wichert WRA, Bohn PW. Ion Accumulation and Migration Effects on Redox Cycling in Nanopore Electrode Arrays at Low Ionic Strength. ACS NANO 2016; 10:3658-64. [PMID: 26910572 DOI: 10.1021/acsnano.6b00049] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Ion permselectivity can lead to accumulation in zero-dimensional nanopores, producing a significant increase in ion concentration, an effect which may be combined with unscreened ion migration to improve sensitivity in electrochemical measurements, as demonstrated by the enormous current amplification (∼2000-fold) previously observed in nanopore electrode arrays (NEA) in the absence of supporting electrolyte. Ionic strength is a key experimental factor that governs the magnitude of the additional current amplification (AFad) beyond simple redox cycling through both ion accumulation and ion migration effects. Separate contributions from ion accumulation and ion migration to the overall AFad were identified by studying NEAs with varying geometries, with larger AFad values being achieved in NEAs with smaller pores. In addition, larger AFad values were observed for Ru(NH3)6(3/2+) than for ferrocenium/ferrocene (Fc(+)/Fc) in aqueous solution, indicating that coupling efficiency in redox cycling can significantly affect AFad. While charged species are required to observe migration effects or ion accumulation, poising the top electrode at an oxidizing potential converts neutral species to cations, which can then exhibit current amplification similar to starting with the cation. The electrical double layer effect was also demonstrated for Fc/Fc(+) in acetonitrile and 1,2-dichloroethane, producing AFad up to 100× at low ionic strength. The pronounced AFad effects demonstrate the advantage of coupling redox cycling with ion accumulation and migration effects for ultrasensitive electrochemical measurements.
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Affiliation(s)
- Chaoxiong Ma
- Department of Chemistry and Biochemistry and ‡Department of Chemical and Biomolecular Engineering, University of Notre Dame , Notre Dame, Indiana 46556, United States
| | - Wei Xu
- Department of Chemistry and Biochemistry and ‡Department of Chemical and Biomolecular Engineering, University of Notre Dame , Notre Dame, Indiana 46556, United States
| | - William R A Wichert
- Department of Chemistry and Biochemistry and ‡Department of Chemical and Biomolecular Engineering, University of Notre Dame , Notre Dame, Indiana 46556, United States
| | - Paul W Bohn
- Department of Chemistry and Biochemistry and ‡Department of Chemical and Biomolecular Engineering, University of Notre Dame , Notre Dame, Indiana 46556, United States
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Oldham KB, Marken F, Myland JC. Theory of unsupported, steady-state, Nernstian, three-ion, twin-electrode, voltammetry: the special case of dual concentration polarization. J Solid State Electrochem 2016. [DOI: 10.1007/s10008-015-3113-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Ma C, Contento NM, Bohn PW. Redox Cycling on Recessed Ring-Disk Nanoelectrode Arrays in the Absence of Supporting Electrolyte. J Am Chem Soc 2014; 136:7225-8. [DOI: 10.1021/ja502052s] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Chaoxiong Ma
- Department
of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Nicholas M. Contento
- Department
of Chemical and Biomolecular Engineering, University of Notre Dame, Notre
Dame, Indiana 46556, United States
| | - Paul W. Bohn
- Department
of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
- Department
of Chemical and Biomolecular Engineering, University of Notre Dame, Notre
Dame, Indiana 46556, United States
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Zhang C, Aoki KJ, Chen J, Nishiumi T. Blocking of two-electron reduction of non-charged species in the absence of supporting electrolyte at nanoelectrodes. J Electroanal Chem (Lausanne) 2013. [DOI: 10.1016/j.jelechem.2013.09.023] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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13
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Belding SR, Compton RG. Cyclic voltammetry in the absence of excess supporting electrolyte: The effect of analyte charge. J Electroanal Chem (Lausanne) 2012. [DOI: 10.1016/j.jelechem.2012.07.023] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Barnes EO, Belding SR, Compton RG. Electrochemical reactions where the variation of supporting electrolyte concentration is mechanistically revealing: ECE-DISP1 processes in which the chemical step is an isomerisation. J Electroanal Chem (Lausanne) 2011. [DOI: 10.1016/j.jelechem.2011.06.029] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Barnes EO, Wang Y, Limon-Petersen JG, Belding SR, Compton RG. Voltammetry in the absence of excess supporting electrolyte – ECE-DISP1 reactions: The electrochemical reduction of 2-nitrobromobenzene in acetonitrile solvent. J Electroanal Chem (Lausanne) 2011. [DOI: 10.1016/j.jelechem.2011.04.017] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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16
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Dickinson EJF, Limon-Petersen JG, Compton RG. The electroneutrality approximation in electrochemistry. J Solid State Electrochem 2011. [DOI: 10.1007/s10008-011-1323-x] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Dumitrescu I, Unwin PR, Wilson NR, Macpherson JV. Single-Walled Carbon Nanotube Network Ultramicroelectrodes. Anal Chem 2008; 80:3598-605. [DOI: 10.1021/ac702518g] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Ioana Dumitrescu
- Departments of Chemistry and Physics, University of Warwick, Coventry, CV4 7AL, U.K
| | - Patrick R. Unwin
- Departments of Chemistry and Physics, University of Warwick, Coventry, CV4 7AL, U.K
| | - Neil R. Wilson
- Departments of Chemistry and Physics, University of Warwick, Coventry, CV4 7AL, U.K
| | - Julie V. Macpherson
- Departments of Chemistry and Physics, University of Warwick, Coventry, CV4 7AL, U.K
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Aoki K, Li T, Chen J, Nishiumi T. Voltammetric electrodes coated with carboxyl latex particles. J Electroanal Chem (Lausanne) 2008. [DOI: 10.1016/j.jelechem.2007.09.035] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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20
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Hyk W, Karbarz M, Misterkiewicz B, Stojek Z. Voltammetric Studies of Diffusional and Migrational Transport of Ferrocene Derivative of Tripeptide Glutathione. J Phys Chem B 2007; 111:13090-6. [DOI: 10.1021/jp073363v] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Wojciech Hyk
- Department of Chemistry, Warsaw University, Pasteura 1, 02-093 Warsaw, Poland, and Department of Chemistry, Technical University of Radom, Chrobrego 27, 26-600 Radom, Poland
| | - Marcin Karbarz
- Department of Chemistry, Warsaw University, Pasteura 1, 02-093 Warsaw, Poland, and Department of Chemistry, Technical University of Radom, Chrobrego 27, 26-600 Radom, Poland
| | - Boguslaw Misterkiewicz
- Department of Chemistry, Warsaw University, Pasteura 1, 02-093 Warsaw, Poland, and Department of Chemistry, Technical University of Radom, Chrobrego 27, 26-600 Radom, Poland
| | - Zbigniew Stojek
- Department of Chemistry, Warsaw University, Pasteura 1, 02-093 Warsaw, Poland, and Department of Chemistry, Technical University of Radom, Chrobrego 27, 26-600 Radom, Poland
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Li L, Du X, Lu Y, Yang Z. Study on the first-step adsorption of dodecyltrimethylammonium bromide solutions on silica wafer surfaces by ultramicroelectrode voltammetry. Electrochem commun 2007. [DOI: 10.1016/j.elecom.2007.06.039] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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Microfluidic voltammetry: simulation of the chronoamperometric response of microband electrodes sited within microreactors. J Solid State Electrochem 2006. [DOI: 10.1007/s10008-006-0179-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Chang JL, Zen JM. Fabrication of disposable ultramicroelectrodes: Characterization and applications. Electrochem commun 2006. [DOI: 10.1016/j.elecom.2006.01.028] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
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Tsujioka N, Imakura S, Nishi N, Kakiuchi T. Voltammetry of Ion Transfer across the Electrochemically Polarized Micro Liquid-Liquid Interface between Water and a Room-temperature Ionic Liquid, Tetrahexylammonium Bis(trifluoromethylsulfonyl)imide, Using a Glass Capillary Micropipette. ANAL SCI 2006; 22:667-71. [PMID: 16770042 DOI: 10.2116/analsci.22.667] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Ion transfer across the polarized interface between a room-temperature ionic liquid (RTIL) or room-temperature molten salt, tetrahexylammonium bis(trifluoromethylsulfonyl)imide (THAC(1)C(1)N), and water has been studied voltammetrically using a micro liquid-liquid interface formed at the orifice of a glass capillary micropipette. A small current of nanoampere level circumvents the problem of the iR drop in the viscous ionic liquid phase. Voltammograms for the transfer of moderately hydrophilic ions, such as BF(4)(-) and ClO(4)(-), from the aqueous phase in the capillary to the bulk of THAC(1)C(1)N in which the capillary is submerged, show steady-state characteristics in that the current does not depend on the scan rate up to a few hundred millivolt per second, and the plateau in the limiting current region is proportional to the bulk concentration of analyte ions. Owing to the steady-state current, which is presumably ascribed to a noncylindrical geometry of the capillary tip, the relative magnitude of the hydrophobicity, or the affnity to the RTIL, of a series of ions can be determined from the half-wave potentials of voltammograms.
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Affiliation(s)
- Norihiro Tsujioka
- Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University, Japan
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Concentration-dependent diffusion in room temperature ionic liquids: a microelectrode study. Electrochem commun 2004. [DOI: 10.1016/j.elecom.2004.06.012] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Watkins JJ, White HS. The role of the electrical double layer and ion pairing on the electrochemical oxidation of hexachloroiridate(III) at Pt electrodes of nanometer dimensions. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2004; 20:5474-83. [PMID: 15986689 DOI: 10.1021/la0496993] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
The steady-state voltammetric oxidation of hexachloroiridate(III), IrCl6(3-) (1-5 mM), in the presence and absence of an excess supporting electrolyte was investigated at disk- and hemispherical-shaped Pt electrodes with radii ranging from 48 nm to 12.5 microm. Thermodynamic, kinetic, and transport parameters that define the shape and magnitude of the voltammetric wave exhibit a complex dependence on whether a supporting electrolyte is present in the solution. First, the half-wave potential, E1/2, for oxidation of IrCl6(3-) shifts to more positive potentials in the presence of a supporting electrolyte, a consequence of the relative difference in the strength of ion pairing of IrCl6(3-) and IrCl6(2-) by the supporting electrolyte cation. E1/2 increases in the order no electrolyte < n-tetrabutylammonium < Na+ approximately K+ approximately Ca2+, but is independent of the supporting electrolyte anion (Cl-, NO3-, PF6-). Second, the heterogeneous electron-transfer rate constant for oxidation of IrCl6(3-) increases by approximately an order of magnitude in the presence of a supporting electrolyte. Third, in the absence of electrolyte, mass transport limited currents deviate significantly from predicted values based on the Nernst-Planck equation, but only when the electrode radius is smaller than ca. 1 microm. The latter two effects (Frumkin and dynamic diffuse layer effects) result from the dependence of interfacial electrical fields and, thus, the rates of electron-transfer and ion migration, on the supporting electrolyte concentration. We also demonstrate that the theoretical shape of the voltammetric response for oxidation or reduction of a highly charged redox species (e.g., IrCl6(3-)) is essentially independent of whether a supporting electrolyte is present in the solution. This finding can greatly simplify the analysis of heterogeneous electron-transfer rates using steady-state voltammetry in low ionic strength solutions.
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Affiliation(s)
- John J Watkins
- Department of Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112, USA
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Goldfarb DL, Corti HR. Diffusion of Decamethylferrocene and Decamethylferrocenium Hexafluorophosphate in Supercritical Trifluoromethane. J Phys Chem B 2004. [DOI: 10.1021/jp034511u] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Affiliation(s)
- Darío L. Goldfarb
- Comisión Nacional de Energía Atómica, Unidad de Actividad Química, Av. Gral. Paz 1499 (1650) San Martín, Buenos Aires, Argentina, and Departamento de Química Inorgánica, Analítica y Química Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón II, Ciudad Universitaria (1428) Buenos Aires, Argentina
| | - Horacio R. Corti
- Comisión Nacional de Energía Atómica, Unidad de Actividad Química, Av. Gral. Paz 1499 (1650) San Martín, Buenos Aires, Argentina, and Departamento de Química Inorgánica, Analítica y Química Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón II, Ciudad Universitaria (1428) Buenos Aires, Argentina
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29
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Silva SM, Bond AM. Contribution of migration current to the voltammetric deposition and stripping of lead with and without added supporting electrolyte at a mercury-free carbon fibre microdisc electrode. Anal Chim Acta 2003. [DOI: 10.1016/s0003-2670(03)00881-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Rüther T, Hultgren VM, Timko BP, Bond AM, Jackson WR, Wedd AG. Electrochemical investigation of photooxidation processes promoted by sulfo-polyoxometalates: coupling of photochemical and electrochemical processes into an effective catalytic cycle. J Am Chem Soc 2003; 125:10133-43. [PMID: 12914478 DOI: 10.1021/ja029348f] [Citation(s) in RCA: 101] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Oxidative photocurrents measured upon irradiation by a 7-W visible light (wavelength 312-700 nm) demonstrated that the sulfo-polyoxometalate anion clusters [S2W18O62]4- (1a), [S2Mo18O62]4- (1b), and [SMo12O40]2- (2) may be activated photochemically to oxidize the organic substrates benzyl alcohol, ethanol, and (-)-menthol. In the case of catalytic photooxidation of benzyl alcohol to benzaldehyde in the presence of 1a, quantitative electrochemical methods have identified pathways for the oxidation of reduced forms of 1 generated during the catalysis. More generally, the oxidation pathways P(n+2)- + 2H+ <==> Pn- + H2 and 2P(n+2)- + O2 + 4H+ <==> 2Pn- + 2H2O have been evaluated by monitoring acidified acetonitrile solutions of the 2e(-)-reduced clusters by rotating disk electrode voltammetry under anaerobic and aerobic conditions, respectively. Neither of the reduced forms 1b(2e-) nor 2(2e-) reacted under these conditions. In contrast, 1a(2e-) was oxidized via both pathways, consistent with its more negative redox potential, with the rate of oxidation by air-oxygen being significantly faster than that by H+. The present work demonstrated that the crucial step necessary to oxidize reduced catalyst in photocatalytic reactions involving the anions studied may be achieved or accelerated by application of an external potential more positive than the first redox potential of the polyoxometalate anion. Voltammetric analysis revealed that this in situ electrolytic regeneration of the reduced catalyst is an option that leads to a viable photoelectrocatalytic pathway, even when the H+ and O2 pathways are not available.
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Affiliation(s)
- Thomas Rüther
- Centre for Green Chemistry, Monash University, Box 23, Melbourne, Victoria 3800, Australia
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Hyk W, Stojek Z. Generalized theory of steady-state voltammetry without a supporting electrolyte. Effect of product and substrate diffusion coefficient diversity. Anal Chem 2002; 74:4805-13. [PMID: 12349987 DOI: 10.1021/ac025765z] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A generalized theory of the steady-state voltammetric response of a microelectrode in the absence of supporting electrolyte and for any values of diffusion coefficients of the substrate and the product of an electrode process is presented. The treatment applies to any reasonable combination of the charge numbers of the substrate, its counterion, and the product. A way to incorporate the activation polarization into the model is also demonstrated. It has been shown that the height, position, and shape of the migrational voltammogram are affected by the ratio of the product to substrate diffusivity (theta). In particular, for the electrode processes with sign retention, unequal diffusivities of electroactive species influence both characteristic points of the voltammogram (the limiting current and the half-wave potential). For charge neutralization processes (uncharged product), the changes in theta parameter are accompanied only by a shift in the half-wave potential. The most dramatic changes in the I-E relation can be observed for the charge reversal processes. In this case, a consecutive increase in theta results in the transition of the voltammogram shape from rapid exponential growth (theta < 1), through ramp shape (theta = 1), to common wave shape (theta > 1). On the basis of the expressions derived for the limiting current (exact and linearized), a possibility of the determination of the diffusion coefficient of the electrode reaction product is demonstrated. In addition, the ranges of theta where the assumption of equal diffusivities of the substrate and the product is obeyed within an insignificant error have been determined quantitatively. The theory has been experimentally verified using voltammetric oxidation of hexacyanoferrate(II).
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Affiliation(s)
- Wojciech Hyk
- Department of Chemistry, Warsaw University, Poland.
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32
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Ma C, Zhang W, Ciszkowska M. Transport of Ions and Electrostatic Interactions in Thermoresponsive Poly(N-Isopropylacrylamide-co-acrylic acid) Hydrogels: Electroanalytical Studies. J Phys Chem B 2001. [DOI: 10.1021/jp0112976] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- ChengSong Ma
- Department of Chemistry, Brooklyn College, City University of New York, Brooklyn, New York 11210-2889
| | - Weimin Zhang
- Department of Chemistry, Brooklyn College, City University of New York, Brooklyn, New York 11210-2889
| | - Malgorzata Ciszkowska
- Department of Chemistry, Brooklyn College, City University of New York, Brooklyn, New York 11210-2889
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33
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Stevens NPC, Rooney MB, Bond AM, Feldberg SW. A Comparison of Simulated and Experimental Voltammograms Obtained for the [Fe(CN)6]3-/4- Couple in the Absence of Added Supporting Electrolyte at a Rotating Disk Electrode. J Phys Chem A 2001. [DOI: 10.1021/jp0103878] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- N. P. C. Stevens
- School of Chemistry, Monash University, Clayton, Victoria 3800, Australia
| | - M. B. Rooney
- School of Chemistry, Monash University, Clayton, Victoria 3800, Australia
| | - A. M. Bond
- School of Chemistry, Monash University, Clayton, Victoria 3800, Australia
| | - S. W. Feldberg
- School of Chemistry, Monash University, Clayton, Victoria 3800, Australia
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34
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Goldfarb DL, Corti HR. Steady-state voltammetric study of the reduction of decamethylferrocenium in dichloromethane at microelectrodes. J Electroanal Chem (Lausanne) 2001. [DOI: 10.1016/s0022-0728(01)00530-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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35
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Bond AM, Coomber DC, Feldberg SW, Oldham KB, Vu T. An experimental evaluation of cyclic voltammetry of multicharged species at macrodisk electrodes in the absence of added supporting electrolyte. Anal Chem 2001; 73:352-9. [PMID: 11199989 DOI: 10.1021/ac000732+] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The reversible reduction of [S2Mo18O62]4- to [S2Mo18O62]5- and [S2Mo18O62]6- at a glassy carbon macrodisk electrode has been studied by cyclic voltammetry in acetonitrile as a function of the concentration of [(C6H13)4N]4[S2Mo18O62] in the absence and presence of [(C6H13)4N]ClO4 as the added supporting electrolyte. Consideration is given to the influence of scan rate, reference-working electrode distance, [(C6H13)4N]4[S2Mo18O62], and electrolyte concentrations. Experimental data confirm theoretical predictions that cyclic voltammetry at a macrodisk electrode is a viable technique for studies of multiply charged electroactive species without added electrolyte, provided the influence of enhanced complexities associated with effects of increased solution resistance, the mass transport contribution from migration, and convection arising from enhanced density gradients are considered. Enhanced density gradients present in the absence of added supporting electrolyte give rise to a more marked dependence of voltammograms on the angle of the electrode and hence lead to significant distortion of wave shapes at low scan rates. The summation of all these obstacles implies that quantitative evaluation of cyclic voltammograms of multiply charged species requires significantly greater care in the absence than in the presence of added supporting electrolyte.
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Affiliation(s)
- A M Bond
- Department of Chemistry, Monash University, Clayton, Victoria, Australia.
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36
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Abstract
The meaning and significance of uncompensated resistance are carefully explained. Many factors influence the uncompensated resistance and several of these are explored in this article, using idealized models of an electrochemical cell. Among the factors whose roles have been elucidated are the shape and size of the cell, the location of the reference electrode, the shape of the working electrode, and the size and position of the counter electrode. Worthwhile compensation is shown to be impossible with microelectrodes.
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Affiliation(s)
- J C Myland
- Department of Chemistry, Trent University, Peterborough, Ontario, Canada
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37
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Computer-aided design and experimental investigation of a hydrodynamic device: the microwire electrode. Anal Chem 2000; 72:3480-5. [PMID: 10952531 DOI: 10.1021/ac991110v] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The development and application of a new electrochemical device using a computer-aided design strategy is reported. This novel design is based on the flow of electrolyte solution past a microwire electrode situated centrally within a large duct. In the design stage, finite element simulations were employed to evaluate feasible working geometries and mass transport rates. The computer-optimized designs were then exploited to construct experimental devices. Steady-state voltammetric measurements were performed for a reversible one-electron-transfer reaction to establish the experimental relationship between electrolysis current and solution velocity. The experimental results are compared to those predicted numerically, and good agreement is found. The numerical studies are also used to establish an empirical relationship between the mass transport limited current and the volume flow rate, providing a simple and quantitative alternative for workers who would prefer to exploit this device without the need to develop the numerical aspects.
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38
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Abstract
Voltammetric studies in the absence of added supporting electrolyte are presently dominated by the use of near-steady-state microelectrode techniques and millimolar or lower depolarizer concentrations. However, with this methodology, large departures from conventional migration-diffusion theory have been reported for the [Fe(CN)6](3-/4-) process at both carbon fiber and platinum microdisk electrodes. In contrast, data obtained in the present study reveal that use of the transient cyclic voltammetric technique at glassy carbon, gold, or platinum macrodisk electrodes and K4[Fe(CN)6] or K3[Fe(CN)6] concentrations of 50 mM or greater provides an approximately reversible response in the absence of added electrolyte. It is suggested that the use of very high [Fe(CN)6](3-) and [Fe(CN)6](4-) concentrations overcomes problems associated with a diffuse double layer and that large electrode surface areas and faster potential sweep rates minimize electrode blockage and passivating phenomena that can plague voltammetric studies at microelectrodes. The cyclic voltammetry of the [Fe(CN)6](3-/4-) couple at a range of concentrations at macroelectrodes in the absence of added inert electrolyte is compared with that obtained in the presence of 1 M KCl. The enhanced influences of uncompensated resistance, migration, and natural convection arising from density gradients under transient conditions at macrodisk electrodes also are considered.
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39
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Oldham KB. Steady-State Voltammetry at a Rotating Disk Electrode in the Absence of Supporting Electrolyte. J Phys Chem B 2000. [DOI: 10.1021/jp994442c] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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40
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Björefors F, Gadomska J, Donten M, Nyholm L, Stojek Z. Influence of Mixed Diffusional, Migrational, and Convective Mass Transport on the Response of a Wall-Tube Microelectrode in a Flow Injection System. Anal Chem 1999; 71:4926-31. [DOI: 10.1021/ac990430b] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Fredrik Björefors
- Department of Chemistry, University of Warsaw, ul. Pasteura 1, PL 02-093 Warsaw, Poland, and Department of Analytical Chemistry, Uppsala University, P.O. Box 531, SE-751 21 Uppsala, Sweden
| | - Joanna Gadomska
- Department of Chemistry, University of Warsaw, ul. Pasteura 1, PL 02-093 Warsaw, Poland, and Department of Analytical Chemistry, Uppsala University, P.O. Box 531, SE-751 21 Uppsala, Sweden
| | - Mikołaj Donten
- Department of Chemistry, University of Warsaw, ul. Pasteura 1, PL 02-093 Warsaw, Poland, and Department of Analytical Chemistry, Uppsala University, P.O. Box 531, SE-751 21 Uppsala, Sweden
| | - Leif Nyholm
- Department of Chemistry, University of Warsaw, ul. Pasteura 1, PL 02-093 Warsaw, Poland, and Department of Analytical Chemistry, Uppsala University, P.O. Box 531, SE-751 21 Uppsala, Sweden
| | - Zbigniew Stojek
- Department of Chemistry, University of Warsaw, ul. Pasteura 1, PL 02-093 Warsaw, Poland, and Department of Analytical Chemistry, Uppsala University, P.O. Box 531, SE-751 21 Uppsala, Sweden
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41
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42
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Ciszkowska M, Stojek Z. Voltammetry in solutions of low ionic strength. Electrochemical and analytical aspects. J Electroanal Chem (Lausanne) 1999. [DOI: 10.1016/s0022-0728(99)00141-2] [Citation(s) in RCA: 98] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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43
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Oldham KB, Feldberg SW. Principle of Unchanging Total Concentration and Its Implications for Modeling Unsupported Transient Voltammetry. J Phys Chem B 1999. [DOI: 10.1021/jp9837939] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Affiliation(s)
- Keith B. Oldham
- Department of Chemistry, Trent University, Peterborough ON, Canada K9J 7B8
| | - Stephen W. Feldberg
- Department of Applied Science, Brookhaven National Laboratory, Upton, New York 11973
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44
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Hyk W, Stojek Z. Reverse Pulse Voltammetry and Double Potential Step Chronoamperometry as Useful Tools for Characterization of Electroactive Systems under the Conditions of Mixed Diffusional and Migrational Transport. Anal Chem 1998. [DOI: 10.1021/ac980748o] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Wojciech Hyk
- Department of Chemistry, University of Warsaw, ul. Pasteura 1, PL-02-093, Warsaw, Poland
| | - Zbigniew Stojek
- Department of Chemistry, University of Warsaw, ul. Pasteura 1, PL-02-093, Warsaw, Poland
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45
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S. Baranski A, Winkler K. The ac-voltammetric study of fast charge transfer processes in benzene solutions. J Electroanal Chem (Lausanne) 1998. [DOI: 10.1016/s0022-0728(98)00190-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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46
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47
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Bond AM, Colton R, Humphrey DG, Mahon PJ, Snook GA, Tedesco V, Walter JN. Systematic Studies of 17-Electron Rhenium(II) Carbonyl Phosphine Complexes. Organometallics 1998. [DOI: 10.1021/om970897h] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Alan M. Bond
- Department of Chemistry, Monash University, Clayton, Victoria 3168, Australia, and School of Chemistry, La Trobe University, Bundoora, Victoria 3083, Australia
| | - Ray Colton
- Department of Chemistry, Monash University, Clayton, Victoria 3168, Australia, and School of Chemistry, La Trobe University, Bundoora, Victoria 3083, Australia
| | - David G. Humphrey
- Department of Chemistry, Monash University, Clayton, Victoria 3168, Australia, and School of Chemistry, La Trobe University, Bundoora, Victoria 3083, Australia
| | - Peter J. Mahon
- Department of Chemistry, Monash University, Clayton, Victoria 3168, Australia, and School of Chemistry, La Trobe University, Bundoora, Victoria 3083, Australia
| | - Graeme A. Snook
- Department of Chemistry, Monash University, Clayton, Victoria 3168, Australia, and School of Chemistry, La Trobe University, Bundoora, Victoria 3083, Australia
| | - Vanda Tedesco
- Department of Chemistry, Monash University, Clayton, Victoria 3168, Australia, and School of Chemistry, La Trobe University, Bundoora, Victoria 3083, Australia
| | - Jacky N. Walter
- Department of Chemistry, Monash University, Clayton, Victoria 3168, Australia, and School of Chemistry, La Trobe University, Bundoora, Victoria 3083, Australia
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48
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Zhou H, Shi Z, Dong S. A novel electrochemical method for simultaneously measuring diffusion coefficient and ion transference number. J Electroanal Chem (Lausanne) 1998. [DOI: 10.1016/s0022-0728(97)00446-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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49
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Cooper JB, Pang S, Albin S, Zheng J, Johnson RM. Fabrication of Boron-Doped CVD Diamond Microelectrodes. Anal Chem 1998; 70:464-7. [DOI: 10.1021/ac970762l] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- John B. Cooper
- Department of Chemistry and Department of Electrical and Computer Engineering, Old Dominion University, Norfolk, Virginia 23529
| | - Song Pang
- Department of Chemistry and Department of Electrical and Computer Engineering, Old Dominion University, Norfolk, Virginia 23529
| | - Sacharia Albin
- Department of Chemistry and Department of Electrical and Computer Engineering, Old Dominion University, Norfolk, Virginia 23529
| | - Jianli Zheng
- Department of Chemistry and Department of Electrical and Computer Engineering, Old Dominion University, Norfolk, Virginia 23529
| | - Robert M. Johnson
- Department of Chemistry and Department of Electrical and Computer Engineering, Old Dominion University, Norfolk, Virginia 23529
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50
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Bond AM, Colton R, Mahon PJ, Snook GA, Tan WT. Voltammetric Oxidation of Solution and Solid Phases of Salts of [V(CO)6]- in Aqueous (Electrolyte) Media. J Phys Chem B 1998. [DOI: 10.1021/jp972830d] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Alan M. Bond
- Department of Chemistry, Monash University, Clayton 3168, Victoria, Australia
| | - Ray Colton
- Department of Chemistry, Monash University, Clayton 3168, Victoria, Australia
| | - Peter J. Mahon
- Department of Chemistry, Monash University, Clayton 3168, Victoria, Australia
| | - Graeme A. Snook
- Department of Chemistry, Monash University, Clayton 3168, Victoria, Australia
| | - Wee T. Tan
- Chemistry Department, Universiti Pertanian Malaysia, 43400 UPM, Serdang, Selangor D.E., Malaysia
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