期刊
ELECTROCHIMICA ACTA
卷 47, 期 19, 页码 3219-3231出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/S0013-4686(02)00242-6
关键词
CO tolerance; in situ XAS; electrocatalysis; cancel bifunctionality
Electrocatalysis of CO tolerance and direct methanol oxidation on PtMo/C (3:1 a/o) has been investigated in a PEM fuel cell environment. While a 3-fold enhancement is observed for CO tolerance when compared with PtRu/C (1:1), no such enhancement occurred for methanol oxidation. In situ XAS at the Pt L and alloying element K edges for Pt/C, PtRu/C and PtMo/C showed that in contrast to PtRu/C, both Mo and Pt surfaces play a distinct role for CO oxidation. While on the Ru surface there is a competition between oxide formation (from activation of water) and CO adsorption, Mo oxide surface showed no affinity for CO. This provided for efficient CO oxidation at low overpotentials on PtMo/C. However, the corresponding behavior for methanol oxidation showed that Mo oxy-hydroxides were inhibited from efficient removal of CO and CHO species in contrast to Ru oxides. The Mo surface oxides also showed a redox couple involving (V to VI) oxidation states in the presence of both CO and methanol. (C) 2002 Elsevier Science Ltd. All rights reserved.
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