In-situ growth of 3D hierarchical γ-FeOOH/Ni3S2 heterostructure as high performance electrocatalyst for overall water splitting

Obtaining efficient, stable, and low-cost electrocatalysts is the key to realizing large-scale water splitting. In this work, three-dimensional (3D) hierarchical γ-iron oxyhydroxide (γ-FeOOH)/Ni3S2 electrocatalyst on Ni foam is constructed for electrochemical overall water splitting. The 3D γ-FeOOH/Ni3S2 heterostructure can effectively enhance active sites and charge transfer capability, also the heterostructure can benefit electronic effect at the interfaces and synergistic effect of multiple components. Therefore, the γ-FeOOH/Ni3S2 exhibits excellent electrocatalytic activity with low overpotentials of 279 mV at 50 mA⋅cm-2 for oxygen evolution reaction and 92 mV at 10 mA⋅cm-2 for hydrogen evolution reaction, respectively. In addition, only a potential of 1.66 V is needed to attain 10 mA⋅cm-2 for the overall water splitting. In particular, the γ-FeOOH/Ni3S2 exhibits long-term stability for 120 h at 10 mA⋅cm-2 without significant degradation. This work provides a valuable idea for obtaining low-cost and high performance bifunctional electrocatalysts for water splitting.