Oxygen Reduction at Shape-Controlled Platinum Nanoparticles and Composite Catalysts Based on (100)Pt Nanocubes on Microporous-Mesoporous Carbon Supports

The electrochemical oxygen reduction reaction (ORR) on bare (100) Pt nanoparticles supported by molybdenum-carbide-derived carbon [(100) Pt-C(Mo2C)] with high specific surface area and controlled microporosity-mesoporosity, pore size distribution, electrical conductivity, and corrosion stability was studied in 0.5m H2SO4 solution by using rotating-disk-electrode and cyclic voltammetry methods. The C(Mo2C) powder was prepared from Mo2C at a fixed chlorination temperature (750 degrees C). Pt nanoparticles were prepared through colloid chemistry and deposited onto/into C(Mo2C) and Vulcan XC72 carbon supports for comparison. The ORR cathodic current densities and half-wave potentials strongly depend on the characteristics of the carbon material used as the support. High values for the ORR current density were calculated for (100) Pt-C(Mo2C) and the half-wave potential is nearly 80 mV more positive compared with that for the (100) Pt-Vulcan XC72 catalyst with a similar catalyst loading.