Investigation of unsupported Pt_Ru catalysts for high temperature methanol electro-oxidation

Two unsupported Pt¯Ru catalysts, varying in the nature and content of RuOx species, were investigated for methanol electro-oxidation in a solid polymer electrolyte fuel cell at high temperature. The catalyst containing a lower amount of ruthenium oxide showed higher catalytic activity and lower mass transport limitations. A physicochemical investigation was carried out to support the interpretation of electrochemical results. Pt¯Ru alloy appears more active than Pt¯RuOx in the chemisorption of labile-bonded oxygenated species, which promote the oxidation of the methanolic residues adsorbed on the catalyst surface.