NiCu alloys anchored CoO nanowire arrays as efficient hydrogen evolution electrocatalysts in alkaline and neutral media.

Robust and long-lasting non-precious metal electrocatalysts are essential to achieve sustainable hydrogen production. In this work, we synthesized CoO@NiCu by electrodepositing NiCu nanoclusters onto CoO nanowire arrays that were formed in situ on nickel foam. The introduction of NiCu nanoclusters altered the inherent electronic structure of CoO, significantly increasing the exposure of active sites and enhancing endogenous electrocatalytic activity. CoO@NiCu exhibited overpotentials of only 20 and 73 mV, respectively, at 10 mA cm current densities in alkaline and neutral media. These values were equivalent to those of commercial Pt catalysts. Finally, the electron accumulation effect at the CoO@NiCu, along with a negative shift in the d-band center, is finally revealed by theoretical calculations. Hydrogen adsorption on consequent electron-rich Cu sites was effectively weakened, leading to a robust catalytic activity for the hydrogen evolution reaction (HER). Overall, this study proposes a practical strategy for creating efficient HER electrocatalysts in both alkaline and neutral media.