A NiP/NiMoO nanocone electrocatalyst for efficient hydrogen evolution: tip-enhanced local electric field effect.

The sluggish kinetics of the hydrogen evolution reaction (HER) result in a high overpotential in alkaline solutions. A high-curvature metal oxide heterostructure can effectively boost the electrocatalytic HER by leveraging the tip-enhanced local electric field effect. Herein, NiP/NiMoO nanocones were synthesised on a nickel foam (NF) substrate by etching a metal-organic framework template. The NiP/NiMoO nanocones on the NF substrate served as an advanced electrocatalyst for the HER. Analysis using the finite element method indicated that the high-curvature tips of the NiP/NiMoO nanocones enhanced the local electric field, resulting in a higher concentration of hydrated K ions (K(HO)), which facilitated water dissociation and accelerated the reaction kinetics. The tip-enhanced local electric field effect accelerates the mass transfer rate, and the heterostructure promotes charge transfer to activate the active center, thereby synergically enhancing the electrocatalytic reaction. The NiP/NiMoO nanocone electrocatalyst exhibited low overpotentials of 49, 137 and 274 mV at 10, 100 and 500 mA cm, respectively, under alkaline conditions for the HER. In addition, the electrocatalyst demonstrated excellent stability over 200 h at 300 mA cm. This study provides a promising approach for developing efficient electrocatalysts that facilitate the HER in alkaline solutions.