Bifunctionality in Pt alloy nanocluster electrocatalysts for enhanced methanol oxidation and CO tolerance in PEM fuel cells: electrochemical and in situ synchrotron spectroscopy |
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Authors: | Sanjeev Mukerjee Richard C. Urian |
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Affiliation: | Department of Chemistry, Northeastern University, 360 Huntington Avenue, Boston, MA 02115-5000, USA |
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Abstract: | 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. |
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Keywords: | CO tolerance In situ XAS Electrocatalysis Cancel bifunctionality |
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