Interfacial electronic reconstruction in Ni(OH)2/NiSe2 heterostructures for enhanced bifunctional electrocatalytic activity toward alkaline OER and HER

Developing earth-abundant and noble-metal-free electrocatalysts with high activity toward the hydrogen evolution reaction (HER) in alkaline media is of great importance for sustainable hydrogen production. Among various optimization strategies, interfacial engineering has emerged as an effective approach for tuning the intrinsic electronic structure and catalytic behavior of transition-metal-based electrocatalysts for both oxygen evolution reaction (OER) and HER. Herein, a novel two-dimensional Ni(OH) 2 /NiSe 2 heterostructure with strong interfacial coupling was successfully constructed through a facile synthesis strategy for efficient alkaline water splitting. Owing to the abundant heterointerfaces and synergistic interactions between the two components, the as-prepared catalyst exhibits remarkable bifunctional electrocatalytic performance in 1 M KOH electrolyte, delivering low overpotentials of 170 mV for OER and 350 mV for HER at a current density of 10 mA‧cm −2 . More importantly, heterointerface-induced electronic reconstruction triggers substantial charge redistribution, which optimizes the adsorption energetics of key reaction intermediates. Combined experimental and DFT investigations reveal that the synergistic modulation of work function, charge transfer, electronic states, and d-band center collectively renders water dissociation thermodynamically more favorable. The enhanced OER and HER performance is attributed to the synergistic effects of increased conductivity and interfacial electronic coupling in the partially selenized Ni(OH) 2 /NiSe 2 heterostructure. This study highlights the critical role of heterointerface engineering in regulating interfacial electronic structures and provides an effective strategy for the rational design of promising bifunctional electrocatalysts toward OER and HER which shows potential candidate for overall water splitting.