Platinum and Mixed Platinum-Metal Monolayer Fuel Cell Electrocatalysts: Design, Activity and Long-term Performance Stability

We have synthesized a new class of electrocatalysts for the oxygen reduction reaction, consisting of a monolayer of Pt or mixed monolayer of Pt and another late transition metal (Au, Pd, Ir, Ru, Rh, Re or Os) deposited on a Pd(111) single crystal or on carbon-supported Pd nanoparticles. Several of these electrocatalysts exhibited very high activity, amounting to 20-fold increase in a Pt mass activity, compared with conventional carbon supported-Pt electrocatalysts. The origin of this effect was identified through a combination of experimental methods, employing electrochemical techniques, x- ray absorption spectroscopy. In addition, we found that gold submonolayer clusters modified Pt or Pt/Pd catalysts have high activity and an exceptional stability against Pt dissolution under potential (0.6-1.1V) cycling regimes. These new electrocatalysts promise to alleviate some major problems of existing fuel cell technology by simultaneously decreasing materials cost and enhancing performance.