Electrochemical preparation of Ni–Mo alloy catalysts for hydrogen evolution reaction based on benzyl alcohol and ethylene glycol mixed solvents

The electrochemical reduction behavior in the preparation of Ni–Mo alloy catalysts using benzyl alcohol (BA) and ethylene glycol (EG) mixed solvents is studied via CV. These studies indicate that the mechanism of Ni–Mo co-deposition corresponds to a typical induced co-deposition mechanism, in which Ni 2+ can facilitate the Mo 6+ reduction while Mo 6+ can suppress the Ni 2+ reduction in the mixed solvents. SEM micrographs reveal that these Ni–Mo alloy catalysts exhibit dense structures composed of 'hillock'-shaped granules, and the size of these granules can be tuned by adjusting the Mo content. XRD pattern reveals that the Ni–Mo catalysts present a nanocrystalline structure with an average crystallite size of 48.7 nm. The experimental data demonstrate that increasing the Mo content in the Ni–Mo alloy catalyst from 5.36 to 11.62 wt% significantly enhances the HER performance. Particularly, the catalyst containing 11.62 wt% Mo demonstrates superior catalytic efficiency in 1 M KOH, requiring an overpotential of merely 58 mV to reach a current density of 10 mA cm −2 .