Structure of Pt/Ru catalysts using X-ray absorption near edge structure studies

Pt/Ru catalysts with two very different structures were examined with X-ray absorption near edge structure (XANES). One sample was an industrial metha nol fuel cell Pt/Ru alloy catalyst black, and the second was a carbon-suppo rted Pt/Ru catalyst. In both cases the as-prepared Pt/Ru catalysts were fou nd, with XANES, to be predominately in the form of Pt and Ru oxides. When t hese catalysts were placed in an electrochemical cell and held in the poten tial region where methanol oxidation occurs, XANES data indicate that the m etal oxides were reduced to the metallic form. These results also demonstra te that conclusions about the electrocatalytic activity of Pt/Ru materials for methanol oxidation drawn from the characterization of as-prepared sampl es have little relevance.