Underwater superaerophobic Ni nanoparticle-decorated nickel–molybdenum nitride nanowire arrays for hydrogen evolution in neutral media

Electrochemical water splitting into hydrogen and oxygen in neutral electrolytes has great significance for future energy supply security, potentially offering a pathway for H2 generation from seawater. However, the electrocatalytic hydrogen evolution reaction (HER) generally occurs at low rates in neutral solutions due to the low proton concentration in such media. Herein, we fabricated a novel HER catalyst capable of efficient H2 evolution in water at neutral pH, comprising a nickel-molybdenum nitride nanowire array modified with metallic Ni nanoparticles (Ni/NiMoN). The entire Ni/NiMoN array was supported on a Cu foam. The Ni nanoparticles promoted the dissociation of adsorbed water to enhance the supply of protons in the neutral electrolyte, whilst the nanowire array imparted the electrode surface with underwater superaerophobic properties, thus allowing H2 gas bubbles to detach from the electrode in a facile manner. On the basis of the synergies realized between the different electrode components, the Ni/NiMoN nanowire array electrode offered exceptional HER performance, with an overpotential of only 37 mV at a current density of 10 mA cm−2 in a neutral electrolyte. Results guide the development of next-generation earth-abundant element electrocatalysts for HER in neutral media. •A Ni-Mo nitride nanowire array modified with Ni nanoparticles was fabricated as H2 evolution reaction (HER) catalyst.•The introduction of a water dissociation catalyst (Ni nanoparticles in this case) can boost the neutral HER performance.•The nanowire array with underwater superaerophobic property allowed H2 gas bubbles to detach from the electrode facilely.•The nanowire array electrocatalyst exhibited outstanding HER performance in a neutral electrolyte.