期刊
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
卷 36, 期 9, 页码 5218-5226出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.ijhydene.2011.01.131
关键词
IrO2 electrode; SiO2 doping; Electrochemical surface structure; Electrocatalytic activity
资金
- NSFC [50871101]
- Zhejiang Provincial Natural Science Foundation of China [Z4100016]
- Qianjiang Talent Program of Zhejiang Province [2010R10046]
- Fundamental Research Funds for the Central Universities [2010QNA3007]
Our previous paper (Electrochim Acta 2010; 55: 4587-4593) reported that doping silica, the largest reserved oxide in the world, significantly improved the apparent electrochemical activity of Ti/IrO2 electrodes for oxygen evolution reaction (OER). In the present work, the electrochemical surface structure of Ti/IrO2 SiO2 composite electrodes and the reaction kinetics of the OER thereon are investigated in details, to deeper understand the positive role of silica incorporation. Both the cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) measurements indicate either inner or outer active surface area of the mixed oxide electrodes, which is quantified by the voltammetric charge (q*) or by the double-layer capacitance (C-dl), constantly increases when increasing the silica content therein under the investigated range of Ir/Si molar ratio. The porosity, defined as the ratio of the inner to total surface area, of the binary oxide films exhibits much higher values than pure IrO2 film. Although the apparent electrocatalytic activity for the OER at composite electrodes is obviously higher than that at IrO2 electrode, the real surface area-normalized activity declines after silica incorporation. The kinetic rate constants of the OER, approximated from the normalized polarization curves, also show dramatically decreased values at silica-doped electrodes. The above-mentioned results suggest that the enhanced apparent electrocatalytical activity of silica-doped IrO2 electrodes might be merely a result of geometric effect. Copyright (C) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.
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