偏钒酸钠对甲酸在Pd/C催化剂上氧化的电催化性能影响的机理

直接甲酸燃料电池的两大问题是Pd催化剂对甲酸氧化的电催化稳定性不好和Pd能催化甲酸分解。研究发现,当Pd/C在偏钒酸钠溶液中浸泡后能吸附上VO3-,吸附上VO3-的Pd/C催化剂对甲酸分解的催化性能会大大降低,由甲酸分解产生的CO的量也大大降低,使Pd/C催化剂被CO毒化的几率也大大降低,因此,在偏钒酸钠溶液中浸泡后的Pd/C催化剂对甲酸氧化的峰电流密度要比没有浸泡的Pd/C催化剂高13%左右。计时电流曲线的测量表明,6000 s时在偏钒酸钠溶液中浸泡后的Pd/C催化剂对甲酸氧化的峰电流密度要比没有浸泡的Pd/C催化剂高42%左右。结果证明,在偏钒酸钠溶液中浸泡能提高Pd/C催化剂对甲酸氧化的电催化活性,特别是电催化稳定性。

Effect of Sodium Trioxovanadate on Electrocatalytic Performance of Carbon Supported Pd Catalyst for Formic Acid Oxidation

The poor electrocatalytic stability of the carbon-supported palladium(Pd/C) catalyst for formic acid oxidation and the catalytic performance of the Pd/C catalyst for the decomposition of formic acid are the two problems of the direct formic acid fuel cell(DFAFC). It was found from the investigation that after the Pd/C catalyst is dipped in NaVO3 solution, VO-3 can be adsorbed on the Pd/C catalyst. After the Pd/C catalyst is adsorbed with VO-3, the catalytic performance of the Pd/C catalyst for the decomposition of formic acid would be significantly inhibited, and the amount of CO produced from the decomposition of formic acid would be reduced, with the poison probability of the Pd/C catalyst by CO significantly reduced. Consequently, the peak current density at the Pd/C catalyst after dipping in NaVO3 solution for formic acid oxidation is 13% higher than that at the Pd/C catalyst without dipping in NaVO3 solution. The measurements of chronoamperometric curves indicate that the peak current density for formic acid oxidation at Pd/C catalyst after dipping in NaVO3 solution for 6000 s is 42% higher than that at the Pd/C catalyst without dipping in NaVO3 solution. The results demonstrate that dipping in NaVO3 solution can improve the electrocatalytic ability of Pd/C toward oxidation of formic acid, especially the electrocatalytic stability.