The electrochemical reduction of VO2+ in acidic solution at high overpotentials

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DOIResolve DOI: http://doi.org/10.1016/j.electacta.2005.05.001
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TypeArticle
Journal titleElectrochimica Acta
Volume51
Issue3
Pages395407; # of pages: 12
Subjectvanadium; High Tafel slope; adsorbed intermediates; carbon electrodes; VRBs
AbstractAn investigation has been carried out to attempt to understand the unusually low apparent symmetry factor observed during the reduction of V(5) at higher overpotentials at carbon electrodes (typically <0.13, or >460mVdecade−1). This reaction is of interest because it occurs in vanadium redox-flow batteries (VRBs) during discharge. Polarisation curves were measured using a rotating disk electrode (RDE). The reaction was not solution mass transport controlled, was pH independent (ca from 0 to 1), and the observed Tafel slope was unaffected by V(5) concentration over a range from 0.031 to 280 mM. Electrode double layer capacitance measurements were also carried out in sulphuric acid with and without vanadium. These tests showed that the presence of V(5) caused a suppression of the normal carbon surface quinone pseudocapacitance, as well as the appearance of two new pseudocapacitance peaks, one around 0.175–0.2V and the other around 0.675–0.725V versus SCE. The observed results do not appear consistent with a precipitated film causing diffusion limitations or causing IR drop. A model is developed to try to explain the data, which involves electron transfer through an adsorbed layer of vanadium.
Publication date
LanguageEnglish
AffiliationNational Research Council Canada (NRC-CNRC); NRC Institute for Chemical Process and Environmental Technology
Peer reviewedYes
NRC number52277
NPARC number16285554
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Record identifiere8942587-7f27-4b2e-9580-ff2abe6dac64
Record created2010-10-27
Record modified2016-05-09
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