Chromium addition improves the performance of carbon-supported Pt electrodes for oxygen reduction in phosphoric acid fuel cells. To clarify the role of chromium and its chemical nature at the electrode surface, we have performed a combined electrochemical/surface science investigation of a series of bulk Pt/sub x/Cr/sub (1-x)/ alloys (0 less than or equal to x less than or equal to 1). In this paper we report the surface characterization of the starting electrodes by XPS, electrochemical results from cyclic voltammetry in 85% phosphoric acid, and post-electrochemical surface characterization. For Cr contents less than 40%, the electrodes were quite stable up …
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Chromium addition improves the performance of carbon-supported Pt electrodes for oxygen reduction in phosphoric acid fuel cells. To clarify the role of chromium and its chemical nature at the electrode surface, we have performed a combined electrochemical/surface science investigation of a series of bulk Pt/sub x/Cr/sub (1-x)/ alloys (0 less than or equal to x less than or equal to 1). In this paper we report the surface characterization of the starting electrodes by XPS, electrochemical results from cyclic voltammetry in 85% phosphoric acid, and post-electrochemical surface characterization. For Cr contents less than 40%, the electrodes were quite stable up to +1.6 V vs DHE. The surface Cr was largely oxidized to Cr/sup +3/ for surfaces at open circuit ad those exposed at potentials < +1.4 V. For intermediate Cr levels, Cr was leached from the surface region by +1.5 V, leaving a porous Pt electrode with increased electrochemical hydrogen adsorption capacity. For Pt/sub 0.2//Cr/sub 0.8/, treatments at +1.4 V and above led to the appearance of Pt/sup 4 +/ and Cr/sup 6 +/ species, apparently stabilized in a porous phosphate overlayer up to 50 A thick. The Pt electrochemical hydrogen adsorption capacity was simultaneously increased by a factor of 15. 18 refs., 4 figs.
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Daube, K. A.; Paffett, M. T.; Gottesfeld, S. & Campbell, C. T.Combined electrochemical/surface science investigations of Pt/Cr alloy electrodes,
article,
January 1, 1985;
New Mexico.
(https://digital.library.unt.edu/ark:/67531/metadc1054134/:
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