Nickel nanoparticles encapsulated inside mesoporous MoO2 for industrially stable anion-exchange membrane water electrolysis

The hydrogen evolution reaction (HER) plays a vital role in the production of green hydrogen, but it still faces practical issues, including low cost-efficiency, reduced catalytic activity and limited lifetime under industry-required ampere-scale current densities. Here we report a heterogeneous nucleation strategy to produce a scaled-up, inexpensive, energy-efficient and highly stable NiMo-based electrode (that is, h-Ni/MoO 2 ) for HER electrolysis. The abundant inner surface formed by H 2 O release during annealing favours an encapsulated structure of the h-Ni/MoO 2 catalyst, that is, Ni nanoparticles in porous MoO 2 matrix, which ensures high HER activity (low overpotential of 70.9 ± 4.5 mV) and high HER stability (over 25,000 h) in 1 M KOH at −1,000 mA cm −2 . When using h-Ni/MoO 2 as the cathode catalyst, practical anion-exchange membrane water electrolysis delivers high activity (for example, 5.6 A cm −2 at 1.8 V and 10.2 A cm −2 at 2.0 V) and high durability (for example, over 2,000 h at 1,000 mA cm −2 ).