Electrocatalytic oxidation of hydrogen on polycrystal and single-crystal nickel electrodes

Abstract The electrocatalytic behaviour of low-index nickel single-crystal electrodes for hydrogen oxidation is discussed in relation to the crystallographic structure of the electrode surface and to the pH of the electrolytic solution. Whereas small structural effects are displayed during surface oxidation and formation of α-Ni(OH) 2 , a strong dependence on the crystal structure of the hydrogen oxidation rate is observed in alkaline medium. Ni(100) and above all Ni(110) are the most active structures, 5 to 6 times more active than polycrystalline nickel. The behaviour of this latter is close to that of Ni(111), particularly at low pH, where dissolution of nickel occurs.