Scanning electrochemical microscopy (SECM) study of pH changes at Pt electrode surfaces in Na2SO4 solution (pH 4) under potential cycling conditions
Scanning electrochemical microscopy (SECM) study of pH changes at Pt electrode surfaces in Na2SO4 solution (pH 4) under potential cycling conditions
pH Changes in the vicinity of a platinum electrode immersed in a 10(-4) mol dm(-3) H2SO4+0.5 mol dm(-3) Na2SO4 solution have been probed with a scanning electrochemical microscope (SECM). Experiments were carried out in the tip substrate voltammetric mode where the faradaic current flowing to the tip is recorded while cycling the potential of the substrate. The tip current was made pH-sensitive by holding the tip potential in a region where a pH-dependent reaction occurs. Three reactions were considered: hydrogen evolution, Pt oxide formation and oxygen evolution. The results provide direct evidence of a pH decrease close to the substrate during hydrogen desorption, oxide formation and oxygen evolution. Conversely, a pH increase is observed during oxide reduction, hydrogen adsorption and hydrogen evolution. A quantitative assessment of pH changes is proposed; variations as large as one pH unit were observed.
acidic aqueous-media, hydrogen adsorption, platinum-electrodes, polycrystalline platinum, supporting electrolyte, formation-reduction, oxide formation, mechanism, behavior, voltammetry
3791-3798
Yang, Yi-Fu
d666aad3-e154-4859-be89-86c4a0dacc58
Denuault, Guy
5c76e69f-e04e-4be5-83c5-e729887ffd4e
1996
Yang, Yi-Fu
d666aad3-e154-4859-be89-86c4a0dacc58
Denuault, Guy
5c76e69f-e04e-4be5-83c5-e729887ffd4e
Yang, Yi-Fu and Denuault, Guy
(1996)
Scanning electrochemical microscopy (SECM) study of pH changes at Pt electrode surfaces in Na2SO4 solution (pH 4) under potential cycling conditions.
Journal of the Chemical Society, Faraday Transactions, 92 (20), .
(doi:10.1039/FT9969203791).
Abstract
pH Changes in the vicinity of a platinum electrode immersed in a 10(-4) mol dm(-3) H2SO4+0.5 mol dm(-3) Na2SO4 solution have been probed with a scanning electrochemical microscope (SECM). Experiments were carried out in the tip substrate voltammetric mode where the faradaic current flowing to the tip is recorded while cycling the potential of the substrate. The tip current was made pH-sensitive by holding the tip potential in a region where a pH-dependent reaction occurs. Three reactions were considered: hydrogen evolution, Pt oxide formation and oxygen evolution. The results provide direct evidence of a pH decrease close to the substrate during hydrogen desorption, oxide formation and oxygen evolution. Conversely, a pH increase is observed during oxide reduction, hydrogen adsorption and hydrogen evolution. A quantitative assessment of pH changes is proposed; variations as large as one pH unit were observed.
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Published date: 1996
Additional Information:
VT016
Keywords:
acidic aqueous-media, hydrogen adsorption, platinum-electrodes, polycrystalline platinum, supporting electrolyte, formation-reduction, oxide formation, mechanism, behavior, voltammetry
Identifiers
Local EPrints ID: 179259
URI: http://eprints.soton.ac.uk/id/eprint/179259
ISSN: 0956-5000
PURE UUID: 9b415868-557b-4f97-b1d0-c7559d7c40fc
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Date deposited: 04 Apr 2011 08:40
Last modified: 15 Mar 2024 02:44
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Author:
Yi-Fu Yang
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