Hierarchical CoP₃/NiMoO₄ heterostructures on Ni foam as an efficient bifunctional electrocatalyst for overall water splitting

Controllable synthesis strategies of the cost-effective and high-active non-noble metal bifunctional electrocatalysts for overall water splitting are imperatively required. Herein, the hierarchical heterostructure CoP₃/NiMoO₄ nanosheets on Ni foam (CoP₃/NiMoO₄–NF) are synthesized by hydrothermal, annealing and phosphorization treatment. The synergistic effect between CoP₃ and NiMoO₄ remarkably promotes the HER intrinsic activity. Moreover, the Ni foam promotes the vertical growth of well-aligned nanosheet arrays, which expose more active sites for HER and OER. The CoP₃/NiMoO₄–NF-2 (Co/Mo = 1/1) electrocatalyst reveals a low overpotential of 92 mV for HER and 347 mV for OER at 10 mA cm⁻² in 1.0 M KOH. Especially, the CoP₃/NiMoO₄–NF-2 exhibits exceptional performance for overall water splitting which presents a low cell voltage of 1.57 V at 10 mA cm⁻², and outstanding durability which could maintain over 12 h. The design strategy and controllable synthesis of the hierarchical heterostructure bifunctional electrocatalyst will be beneficial for efficient overall water splitting.