Investigation of enhanced CO tolerance in proton exchange membrane fuel cells by carbon supported PtMo alloy catalyst

We report a two- to threefold enhancement of CO tolerance in a proton excha nge membrane (PEM) fuel cell, exhibited by carbon supported nanocrystalline PtMo/C as compared to the current state of the art PtRu/C electrocatalysts . The bulk of these nanocrystals were comprised of Pt alloyed with Mo in th e ratio 8.7: 1.3 as shown by both X-ray diffraction and in situ extended X- ray absorption fine structure measurements. Rotating disk electrode measure ments and cyclic voltammetry in a PEM fuel cell indicate the onset of CO ox idation at potentials as low as 0.1 V. Further, the oxidation of CO exhibit s two distinct peaks, indicating redox behavior involving oxyhydroxides of Mo. This is supported by in situ X-ray absorption near edge structure measu rements at the Mo K edge. (C) 1999 The Electrochemical Society. S1099-0062( 98) 08-029-8. All rights reserved.