XPS study of surface oxidation of carbon-supported Pt catalysts

Pt/C catalysts for phosphoric acid fuel cells (PAFC) applications have been studied by X-ray photoelectron spectroscopy (XPS) and potentiometric titration in aqueous suspensions. Catalysts activated at temperatures in the range 800-950°C have shown a significant amount of C edge and C ? functionalities which generate a variable amount of pyrone-type complexes after exposure to air. The relative amount of such basic group has been found to effect the amount of Pt oxidized and hence the electrochemically active surface area of the catalysts.