Electrochemical oxidation of the carbon support to synthesize Pt(Cu) and Pt-Ru(Cu) core-shell electrocatalysts for low-temperature fuel cells

Abstract

Pt and Pt-Ru shells on Cu cores supported on Vulcan carbon XC72R have been synthesized and tested as possible anode electrocatalysts for polymer electrolyte fuel cells. Pt(Cu)/C was prepared by Cu electrodeposition on the black carbon support at constant potential followed by Pt deposition on Cu by galvanic exchange, whereas Pt-Ru(Cu)/C was prepared by spontaneous deposition of Ru species on Pt(Cu)/C. The corresponding cyclic voltammograms in 0.5 M H2SO4 solution showed the hydrogen adsorption/desorption peaks and no Cu oxidation. The respective CO stripping peak potentials of Pt(Cu)/C and Pt-Ru(Cu)/C were about 0.1 and 0.2 V more negative than those corresponding to Pt/C and Ru-decorated Pt/C. The best conditions for CO oxidation were found for Cu deposition potentials between -0.2 and -0.4 V vs Ag/AgCl/KCl(sat). The Pt economy of the Pt-Ru(Cu)/C system was proved for the methanol oxidation, with specific currents more than twice those obtained on the Ru-decorated commercial Pt/C catalysts.