Interfacial coupling and defect-rich FeNi LDH/SnS2 hierarchical heterostructures for robust overall water splitting

Developing efficient, durable non-noble bifunctional electrocatalysts is key for overall water splitting. Herein, we present a hierarchical FeNi LDH/SnS 2 heterojunction array integrating cation vacancy engineering with heterointerface construction. The multilevel architecture comprises a conductive carbon cloth skeleton, SnS 2 nanosheet scaffolds, and cation-vacancy-rich FeNi LDH nanosheets. Vacancies modulate the electronic structure of FeNi LDH, while the heterointerface induces directional electron transfer to SnS 2 . Density functional theory calculations reveal elevated density of states near the Fermi level and optimized d -band center for balanced intermediate adsorption/desorption. Consequently, the cation-vacancy-rich FeNi LDH/SnS 2 electrode achieves outstanding bifunctional activity in alkaline media, with overpotentials of only 100 mV (hydrogen evolution reaction) and 197 mV (oxygen evolution reaction) at 10 mA cm −2 . An overall water splitting electrolyzer requires just 1.52 V to reach 10 mA cm −2 and operates stably over 140 h, surpassing Pt/C||IrO 2 . This work offers an effective strategy for designing high-performance bifunctional electrocatalysts.