A Ni2P/NiMoOx nanocone electrocatalyst for efficient hydrogen evolution: tip-enhanced local electric field effect

Abstract

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, Ni₂P/NiMoO_x nanocones were synthesised on a nickel foam (NF) substrate by etching a metal–organic framework template. The Ni₂P/NiMoO_x 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 Ni₂P/NiMoO_x nanocones enhanced the local electric field, resulting in a higher concentration of hydrated K⁺ ions (K(H₂O)₆⁺), 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 Ni₂P/NiMoO_x nanocone electrocatalyst exhibited low overpotentials of 49, 137 and 274 mV at 10, 100 and 500 mA cm⁻², respectively, under alkaline conditions for the HER. In addition, the electrocatalyst demonstrated excellent stability over 200 h at 300 mA cm⁻². This study provides a promising approach for developing efficient electrocatalysts that facilitate the HER in alkaline solutions.