Pd-based bimetallic catalysts for direct formic acid fuel cells

Pd-M (M = Cu and Ni) bimetallic catalysts (films and core-shell nanoparticles) were studied by examining the effect of electronic structural perturbation on the electrochemical activity of the Pd surface toward formic acid oxidation. X-ray photoelectron spectroscopy (XPS) and cyclic voltammetry (CV) are used to obtain the valence band spectra and d-band center shifts and electrochemical activities of the catalysts. XPS analysis indicates a charge transfer from Pd to the transition metals. This electronic perturbation results in an alteration of the interaction between the intermediate species and the Pd surface. As a result, an increase in current density and an improvement in stability of formic acid electrochemical oxidation are observed for the Pd-based bimetallic system compared to pure Pd.