Co-deposition of Pt-HXMoO3 and its catalysis on methanol oxidation in sulfuric acid solution

The deposition or co-deposition of Pt and/or Pt-HxMoO3(0<y<x<2) on a flat base platinum electrode from 0.5M H2SO4 solutions with 0.005M H2PtCl6 and/or 0.05M Na2MoO4 and the catalytic oxidation of methanol on deposited and co-deposited electrodes in 0.1M CH3OH + 0.5M H2SO4 solution were studied by cyclic voltammetry, choronoamperometry and alternative current impedance spectroscopy. A deposited platinum electrode obtained by cycling the base platinum from -0.2 to 0.8V (vs. SCE) in 0.005M H2PtCl6 + 0.5M H2SO4 solution had a larger surface area than the base platinum electrode. Hydrogen molybdenum bronze (HxMoO3) was deposited and could be oxidized in two steps to HyMoO(3) (y<x) when the base platinum electrode was cycled from -0.2 to 1.3V (vs. SCE) in 0.05M Na2MoO4 + 0.5M H2SO4 solution. A Pt-HxMoO3 co-deposited electrode could be obtained by cycling the base platinum electrode from -0.2 to 0.8V (vs. SCE) in 0.05M Na2MoO4 + 0.005M H2PtCl6 + 0.5M H2SO4 solution. There is a significant catalysis for methanol oxidation at the co-deposited electrode in 0.5M H2SO4 solution. The catalysis was ascribed to the interaction between platinum and the redox couple HxMoO3/ HyMoO3 (0<y<x<2). The hydrogen molybdenum bronzes with less hydrogen play a role as hydrogen acceptor which help to free platinum from poison by the intermediates of methanol oxidation. The instability of the codeposited electrode in 0.5M H2SO4 solution was proposed.