物理化学学报 >> 2000, Vol. 16 >> Issue (10): 906-911.doi: 10.3866/PKU.WHXB20001008

研究论文 上一篇    下一篇

甲酸在铂电极上吸附氧化机理研究

向娟, 吴秉亮, 陈胜利   

  1. 武汉大学化学与环境科学学院 武汉 430072
  • 收稿日期:2000-03-14 修回日期:2000-05-07 发布日期:2000-10-15
  • 通讯作者: 吴秉亮 E-mail:blwu@whu.edu.cn

An EQCM Investigation of the Mechanism of Surface Electro-oxidation of Formic Acid on Pt-electrode

Xiang Juan, Wu Bing-Liang, Chen Sheng-Li   

  1. Department of Chemistry,Wuhan University,Wuhan 430072
  • Received:2000-03-14 Revised:2000-05-07 Published:2000-10-15
  • Contact: Wu Bing-Liang E-mail:blwu@whu.edu.cn

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摘要：

用时间分辨石英晶体微天平（ Time-resolved EQCM）、循环伏安法及电化学阶跃技术，研究了铂电极上甲酸的吸附氧化过程 .结果表明，在活性吸附氧化过程中，甲酸吸附后迅速失去一个电子形成 COOHad单分子层，在阶跃电势计时电流图上得到一个氧化电流峰及 EQCM图上一个相应的质量增加，随后的 COOHad氧化是一个速率较慢的过程，当它的吸附达到稳态以后，甲酸氧化反应在计时电流图上表现为稳态小电流及相应的 EQCM质量平阶 .因而可以将不同的反应步骤归属于不同的阶段 .并由此得到了不同电势下 COOHad氧化的电化学反应速率常数，并求出 COOHad进一步电化学氧化步骤的电子传递系数β=0.191.

关键词: 甲酸, 铂电极, 时间分辨EQCM, 吸附, 速率常数

Abstract:

The adsorption and oxidation of formic acid in a sulfuric acid medium on a platinum electrode were investigated using the time-resolved electrochemical quartz crystal microbalance(Time-resolved EQCM). A programmed potential step procedure was used to overcome the self- poisoning involved in the oxidation of formic acid. The results demonstrated that the reactive oxidation of formic acid produced COOHad as the first electron transfer process at the initial stage. It was a fast process corresponding to an oxidation current peak on the chronoamperometric plot. At the second stage, further oxidation of COOHad corresponded to a steady current and unchanged mass, which was a slow process. Based on the steady current of the further oxidation of COOHad at different adsorption potentials, the reaction rate constants and the transfer coefficient were obtained.

Key words: Formic acid, Pt electrode, Time-resolved EQCM, Adsorption, Rate constant