Pt-Cu/C and Pd Modified Pt-Cu/C electrocatalysts for the oxygen reduction reaction in direct methanol fuel cells

Abstract

In this work, different carbon supported Pt-Cu catalysts and Pd modified Pt-Cu catalysts were prepared by chemical reduction of Pt, Cu and Pd precursors with sodium borohydride, and their electrocatalytic activity for the oxygen reduction reaction was studied. X-ray diffraction analysis indicated alloy formation. Transmission electron microscopy (TEM) showed that the metal nanoparticles are well-distributed on the carbon support. Dispersive X-ray absorption spectroscopy (DXAS) was used to achieve a better understanding of the intrinsic properties of the materials. The electrocatalysts were characterized electrochemically by cyclic voltammetry in 0.5 mol L-1 H2SO4 and their electrochemical activity was studied with steady-state experiments in a direct methanol fuel cell (DMFC). The introduction of Pd led to an improvement of the catalytic activity of the Pt-Cu catalysts. The best performance in a DMFC was obtained using, as cathode, a Pt50Pd40Cu10/C alloy catalyst thermally treated at 500 ºC in an H2/Ar atmosphere.