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

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.