Bifunctional Electrocatalyst Enhanced Synergistically by MoS₂/Ni₃S₂ Heterojunctions and Au Nanoparticles for Large‐Current‐Density Overall Water Splitting

Abstract Developing transition metal based overall water splitting (OWS) electrocatalysts with high efficiency, low‐cost, large current density, and long‐term stability is crucial for industrial electrolysis of water, but remains a major challenge. In this study, a hierarchical electrocatalyst with MoS 2 /Ni 3 S 2 heterojunctions and a tiny amount of Au nanoparticles grown on nickel foam (MoS 2 /Ni 3 S 2 ‐Au@NF) has been developed by a one‐step hydrothermal method. The heterojunctions and Au nanoparticle decoration induce the electron‐rich interfaces in the catalyst, which facilitate the synergistic adsorption of both OER and HER intermediates. As a result, MoS 2 /Ni 3 S 2 ‐Au@NF possesses an excellent bifunctional electrocatalytic performance in 1 M KOH with low HER overpotential (78 mV@10 mA cm −2 , 253 mV@500 mA cm −2 ), low OER overpotential (261 mV@50 mA cm −2 , 435 mV@500 mA cm −2 ), and outstanding cyclical stability and continuous stability, which are superior than typical benchmarks of Pt/C and RuO 2 . An electrolyzer assembled with the self‐supported MoS 2 /Ni 3 S 2 ‐Au@NF electrode also displays excellent OWS activity and stability with a current density beyond 100 mA cm −2 . This experiment is responding a potential alternative non‐precious metal electrocatalyst for OWS at industrial settings, and thus promotes the real‐world application of hydrogen energy conversions.