In Situ Fast Construction of Ni3S4/FeS Catalysts on 3D Foam Structure Achieving Stable Large‐Current‐Density Water Oxidation

Abstract By increasing the content of Ni3+, the catalytic activity of nickel‐based catalysts for the oxygen evolution reaction (OER), which is still problematic with current synthesis routes, can be increased. Herein, a Ni3+‐rich of Ni3S4/FeS on FeNi Foam (Ni3S4/FeS@FNF) via anodic electrodeposition to direct obtain high valence metal ions for OER catalyst is presented. XPS showed that the introduction of Fe not only further increased the Ni3+ concentration in Ni3S4/FeS to 95.02%, but also inhibited the dissolution of NiOOH by up to seven times. Furthermore, the OER kinetics is enhanced by the combination of the inner Ni3S4/FeS heterostructures and the electrochemically induced surface layers of oxides/hydroxides. Ni3S4/FeS@FNF shows the most excellent OER activity with a low Tafel slope of 11.2 mV dec−1 and overpotentials of 196 and 445 mV at current densities of 10 and 1400 mA cm−2, respectively. Furthermore, the Ni3S4/FeS@FNF catalyst can be operated stably at 1500 mA cm−2 for 200 h without significant performance degradation. In conclusion, this work has significantly increased the high activity Ni3+ content in nickel‐based OER electrocatalysts through an anodic electrodeposition strategy. The preparation process is time‐saving and mature, which is expected to be applied in large‐scale industrialization.