Co-deposition of Ni-Mo alloy film catalysts for hydrogen evolution from an ethylene glycol system

Owing to the depletion of renewable energy sources, manufacturing stable, efficient and economical non-noble electrode materials for the hydrogen evolution reaction (HER) through electrochemical water splitting is a promising avenue. In this work, Ni-Mo alloy films containing different Mo concentrations were synthesized via potentiostatic technique, and the mechanism of Ni²⁺ and Mo⁶⁺ co-deposition in an ethylene glycol system (EG) was recorded. The co-deposition mechanism of Mo⁶⁺ and Ni²⁺ in the EG shows that the existence of Ni²⁺ can facilitate the reduction of Mo⁶⁺, while Mo⁶⁺ can impede the reduction of Ni²⁺. Furthermore, both functions could be reinforced owing to the improved content of Ni²⁺ and Mo⁶⁺ in the EG system. Ni-Mo alloy films containing different Mo concentrations could be obtained from the EG solution, and their microstructures could be changed by changing the Mo content. Scanning electron microscopy micrographs exhibit that Ni-Mo alloy films with 10.84 wt% Mo show a cauliflower-like pattern. Benefiting from the alloying technique to modify the Ni electronic structure with Mo, coupled with the concurrent presence of an appropriate cauliflower-like structure, Ni-Mo alloy films with 10.84 wt% Mo show remarkable catalytic activity and durability with an HER overpotential of 74 mV (η ₁₀, overpotential was recorded at j = 10 mA cm^-2) in 1.0 M KOH solution.