Hydrogen evolution characteristics of sputter-deposited Co-Mo, Co-Al and Co-Mo-Al alloy electrodes in NaOH solution

Binary Co-Mo and Co-Al, and ternary Co-Mo-Al alloy electrodes for hydrogen evolution were prepared by using sputter deposition on a nickel substrate with good adhesion. The hydrogen evolution reaction (HER) of these alloy electrodes in the deaerated 1 kmol·m^-3 NaOH at 303 K is enhanced significantly compared with pure cobalt electrode. The effective surface area of these alloy electrodes estimated from ac impedance technique is largely increased by leaching of aluminum into alkaline solution. The electrocatalytic activity sequence is Co-Mo-Al>Co-Mo>Co-Al. The maximum activity is obtained for Co-10Mo-58Al alloy with a hydrogen overpotential as low as 110 mV at 10³ A·m^-2. The enhancement of HER is attributed to both the synergistic effect of alloy constituents and the large effective surface area.