乙醇在钯电极上的电氧化机理

Mechanism of Ethanol Electrooxidation on Pd Electrode

利用循环伏安与现场傅里叶变换红外(FTIR)光谱对乙醇在Pd电极上的电氧化机理进行了研究.循环伏安测量表明,乙醇在Pd上氧化的性能受pH值与乙醇浓度的影响.当溶液pH>11.0时,Pd对乙醇才具有催化性能,而且乙醇在Pd上氧化的性能随着pH值和乙醇浓度的增加而提高.现场红外光谱电化学测量结果证明,乙醇在不同pH溶液中的氧化反应机理和产物不同.当溶液pH>13.0时,产物只有乙酸盐,说明乙醇仅发生部分氧化,乙醇中的C—C键没有断裂.当溶液pH≤13.0时,尽管乙醇在Pd电极上的氧化活性受到抑制,却发生完全氧化而产生二氧化碳,说明乙醇的C—C键在低碱环境中容易断裂,最后乙醇被完全氧化.实验中没有检测到CO,表明该反应途径是一个非毒化过程.

The mechanism of ethanol electrooxidation on a Pd electrode was studied by cyclic voltammetry and in situ Fourier transform infrared （FTIR） spectroelectrochemistry. We found that the catalytic activity of the Pd electrode for ethanol oxidation was affected by the pH value of the solution and the concentration of ethanol. Catalytic reactions could not proceed until the solution pH〉11.0. The performance for ethanol oxidation on Pd was improved with the increase in the pH value and ethanol concentration. The in situ PTIR spectroelectrochemical measurements indicated that the reaction mechanism and products depend on the pH value of the reaction solution. The main oxidation product was acetate at pH〉13.0. The C-C bond cleavage of ethanol occurred as evidenced by the formation of CO2 at pH ≤13.0, however, the catalytic activity for ethanol oxidation was quite low. No CO formation was detected during the oxidation of ethanol by PTIR spectroscopy, indicating the electrooxidation was a non-poisoning process.