Preparation of carbon supported binary Pt-M alloy catalysts (M = first row transition metals) by low/medium temperature methods

Carbon supported Pt alloyed with first row transition elements (Pt-M/C) is being used as improved cathode catalyst for low temperature fuel cells. These catalysts have been usually prepared by deposition of the non-precious metal onto pre-formed carbon supported platinum, followed by alloying at temperatures of the order or above 700 degrees C. As the thermal treatment at high temperature gives rise to an undesired metal particle growth, synthetic methods based on the simultaneous deposition of Pt and M on the carbon substrate, followed by thermal treatment at lower temperature have been developed. In this paper the formation of Pt-M/C by low/intermediate temperature methods is reviewed. Moreover, to investigate the effect of the conditions used in the synthesis on the Pt:M atomic ratio, the degree of alloying and the particle size, carbon supported Pt-Co electrocatalysts with nominal Pt:Co atomic ratio 75:25 were prepared by a low temperature chemical reduction of the precursors with sodium borohydride at two different temperatures and NaBH4 concentrations. The physical characterization of these electrocatalysts was performed by energy dispersive X-ray analysis and X-ray diffraction. (c) 2006 Elsevier B.V. All rights reserved.