Transition metal phosphide catalysts for hydrogen oxidation reaction

A series of transition metal phosphides consisting of tungsten (WP), cobalt (CoP), nickel (NiP), nickel–tungsten (Ni–WP), cobalt–tungsten (Co–WP) and cobalt–molybdenum (Co–MoP) was prepared by a temperature-programmed reduction process. Hydrogen oxidation activities for the phosphide compounds were studied. The hydrogen oxidation reaction (HOR) was determined using a half-cell rotating disc electrode in a 0.5 M H2SO4 electrolyte. In addition, the passivity of the phosphides in an acidic environment was studied by ICP. The Co–WP demonstrated the highest activity for the HOR based on chronoamperometry and the exchange current density. The single WP exhibited a low HOR activity, but the incorporation of Ni or Co enhanced the activity. In contrast, WP exhibited a high passivity, while NiP and CoP dissolved in the 0.5 M H2SO4. The high activities over Co–WP and Ni–WP were attributed to the role of WP in preventing the Co and Ni from corroding in the acidic media.