Methanol Electro-Oxidation on the Pt Surface: Revisiting the Cyclic Voltammetry Interpretation

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• 作者：Dong Young Chung ; Kyung-Jae Lee ; Yung-Eun Sung
• 刊名：Journal of Physical Chemistry C
• 出版年：2016
• 出版时间：May 5, 2016
• 年：2016
• 卷：120
• 期：17
• 页码：9028-9035
• 全文大小：537K
• 年卷期：0
• ISSN：1932-7455

文摘

Methanol is a promising fuel for direct methanol fuel cells in portable devices. A deeper understanding of its electro-oxidation is needed for evaluating electrocatalytic performance and catalyst design. Here we provide an in-depth investigation of the cyclic voltammetry (CV) of methanol electro-oxidation. The oxidation peak in backward scan is shown to be unrelated to residual intermediate oxidation. The origin of the second oxidation peak (I_f2) is expected to the methanol oxidation on Pt–O_x. Electrochemical impedance spectroscopy coupled with CV reveals the origin of CV hysteresis to be a shift in the rate-determining step, from methanol dehydration to OH adsorption by water dissociation, induced by a change in Pt surface coverage with oxygenated species. The peak ratio between forward oxidation peak current (I_f) and backward oxidation peak current (I_b), which is I_f/I_b, is not related to the degree of CO tolerance but to the degree of oxophilicity indeed.