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Transient studies at microelectrodes

Transient studies at microelectrodes
Transient studies at microelectrodes
Transient studies of electrochemical systems at microelectrodes allow analysis under rapid mass transport conditions. The small active area allows rapid resolution of charging currents, giving access to meaningful information even at short times. Sampled current voltammetry at microelectrodes (MSCV) is a multistep technique whereby data is collected from a series of potential step experiments along the redox wave of interest. Varying the sampling time allows comparison of how a reaction proceeds at varying timescales, whilst simultaneously showing the potential dependence. Selection of an appropriate sampling time tunes the rate of mass transport to give quasireversible conditions, allowing facile kinetic analysis using quasireversible models. Application to the oxygen reduction reaction (ORR) revealed unreasonably large currents at short times. This work suggests that pre-adsorbed oxygen at the electrode surface is responsible. The presence of the pre-adsorbed oxygen was confirmed by its direct reduction in argon purged solution, and its strong dependence on the metal substrate. The resultant peak potentials were used to calculate the binding energies of varying metals towards oxygen (?G?), which are in excellent agreement with the literature. This is useful, as ?G? is a popular descriptor for oxygen reduction activity. Once the pre-adsorbed oxygen is consumed, MSCVs for the ORR can be used for standard kinetic analysis using Tafel or Koutecky-Levich analyses, with the advantage of the electrode being oxide free before each data point is recorded.
Perry, Samuel C.
b2cf1718-6005-4894-b88b-a17fc7a2ee61
Perry, Samuel C.
b2cf1718-6005-4894-b88b-a17fc7a2ee61
Denuault, Guy
5c76e69f-e04e-4be5-83c5-e729887ffd4e

(2015) Transient studies at microelectrodes. University of Southampton, Chemistry, Doctoral Thesis, 245pp.

Record type: Thesis (Doctoral)

Abstract

Transient studies of electrochemical systems at microelectrodes allow analysis under rapid mass transport conditions. The small active area allows rapid resolution of charging currents, giving access to meaningful information even at short times. Sampled current voltammetry at microelectrodes (MSCV) is a multistep technique whereby data is collected from a series of potential step experiments along the redox wave of interest. Varying the sampling time allows comparison of how a reaction proceeds at varying timescales, whilst simultaneously showing the potential dependence. Selection of an appropriate sampling time tunes the rate of mass transport to give quasireversible conditions, allowing facile kinetic analysis using quasireversible models. Application to the oxygen reduction reaction (ORR) revealed unreasonably large currents at short times. This work suggests that pre-adsorbed oxygen at the electrode surface is responsible. The presence of the pre-adsorbed oxygen was confirmed by its direct reduction in argon purged solution, and its strong dependence on the metal substrate. The resultant peak potentials were used to calculate the binding energies of varying metals towards oxygen (?G?), which are in excellent agreement with the literature. This is useful, as ?G? is a popular descriptor for oxygen reduction activity. Once the pre-adsorbed oxygen is consumed, MSCVs for the ORR can be used for standard kinetic analysis using Tafel or Koutecky-Levich analyses, with the advantage of the electrode being oxide free before each data point is recorded.

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More information

Published date: October 2015
Organisations: University of Southampton, Chemistry

Identifiers

Local EPrints ID: 387227
URI: http://eprints.soton.ac.uk/id/eprint/387227
PURE UUID: 2bad3d04-f79c-4c2b-b405-0ba2e32be6e1
ORCID for Guy Denuault: ORCID iD orcid.org/0000-0002-8630-9492

Catalogue record

Date deposited: 16 Feb 2016 12:28
Last modified: 25 Jan 2019 05:01

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