铂、铂钴和铂钌电极上耐一氧化碳氢氧化反应活性的温度依赖性。

Temperature dependence of CO-tolerant hydrogen oxidation reaction activity at Pt, Pt-Co, and Pt-Ru electrodes.

作者信息

Uchida Hiroyuki, Izumi Kenji, Watanabe Masahiro

机构信息

Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Takeda 4, Kofu 400-8510, Japan.

出版信息

J Phys Chem B. 2006 Nov 2;110(43):21924-30. doi: 10.1021/jp064190x.

DOI:10.1021/jp064190x

PMID:17064160

Abstract

The temperature dependence of CO-tolerant H2 oxidation reaction (HOR) activity at Pt, Pt-Co, and Pt-Ru electrodes in 0.1 M HClO4 solution was examined with a channel flow electrode at 30 to 90 degrees C. The kinetically controlled current density (j(K)) for the HOR at Pt decreased seriously at CO overage (theta(CO)) >0.6 in the whole temperature range examined. In contrast, the Pt-Ru alloy exhibited an excellent CO tolerance: only 15% reduction in j(K) even at theta(CO) = 0.6 and 30 degrees C. The Pt-Co alloy also showed moderate CO tolerance up to 70 degrees C. It was found for these alloys that the CO adsorption rate was much slower than that of Pt and the HOR sites were not so rigidly blocked by adsorbed CO due to its enhanced mobility, resulting from their modified electronic structure of surface Pt sites. The activation energies for the apparent rate constants for the HOR were as low as 3.0 and 5.3 kJ mol(-1) at Pt and Pt-Ru, respectively, indicating that the high-temperature operation increases CO-free HOR sites as well as enhancing the HOR kinetics.

摘要

使用通道流动电极在30至90摄氏度下研究了0.1 M高氯酸溶液中Pt、Pt-Co和Pt-Ru电极上耐CO的H2氧化反应（HOR）活性的温度依赖性。在整个研究温度范围内，当CO覆盖度（θ(CO)）>0.6时，Pt上HOR的动力学控制电流密度（j(K)）严重下降。相比之下，Pt-Ru合金表现出优异的CO耐受性：即使在θ(CO)=0.6和30摄氏度时，j(K)也仅降低15%。Pt-Co合金在高达70摄氏度时也表现出适度的CO耐受性。对于这些合金发现，CO吸附速率比Pt慢得多，并且由于表面Pt位点的电子结构改性导致吸附的CO迁移率增强，HOR位点没有被吸附的CO如此严格地阻断。Pt和Pt-Ru上HOR表观速率常数的活化能分别低至3.0和5.3 kJ mol(-1)，这表明高温操作增加了无CO的HOR位点并增强了HOR动力学。