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

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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.