Amorphous Ni–Ti and Ni–Zr Alloys for Water Electrolysis Cathode Materials

Abstract

Abstract Amorphous Ni–Ti and Ni–Zr alloys for their possible use in water electrolysis cathode materials were investigated. The hydrogen electrode reaction in 1 M NaOH (1 M= 1 mol dm−3) proceeds via the Volmer-Tafel reaction route with mixed rate-determining characteristics. The electrocatalytic activity is augmented significantly with a treatment of the alloy electrodes with aq HF. Thus, the exchange current density reaches 10−3A cm−2 (apparent) at 303 K. The activation energy values are 9.4, 5.5, and 6.1 kcal mol−1 (1 cal=4.184J) for the Volmer and Tafel step and the overall reaction, respectively. Surface analyses of the electrodes have indicated that such a high activity is caused by a stable porous Ni layer which is formed on the surface by the acid treatment. Such a porous Ni layer was not effectively formed if the alloys were in crystalline states.