Sulfur Vacancy-Engineered Co₃S₄/MoS₂-Interfaced Nanosheet Array for Enhanced Alkaline Overall Water Splitting

Electrochemical water splitting, a crucial reaction for renewable energy storage, demands highly efficient and stable catalysts. Defect and interface engineering has been widely acknowledged to play a pivotal role in improving electrocatalytic performance. Herein, we demonstrate a facile strategy to construct sulfur vacancy (S v )-engineered Co 3 S 4 /MoS 2 -interfaced nanosheet arrays to modulate the interface electronic structure in situ reduction with NaBH 4 . The abundant sulfur vacancies and well-arranged nanosheet arrays in S v -Co 3 S 4 /MoS 2 lead to pronounced electrocatalytic properties for hydrogen and oxygen evolution reactions (HER/OER) in an alkaline medium, with observed overpotentials of 156 and 209 mV at 10 mA cm –2, respectively. Additionally, as a bifunctional electrocatalyst, S v -Co 3 S 4 /MoS 2 requires a cell voltage of 1.67 V at 10 mA cm –2 for overall water splitting and exhibits long-term stability with activity sustained for more than 20 h. This study provides a novel approach to producing transition metal compound-interfaced electrocatalysts with rich vacancies under mild conditions, showcasing their potential for efficient water splitting applications.