Interfacial Synergism in NiMoO₄/FeOOH Heterostructure for Enhanced Alkaline Oxygen Evolution and Urea Oxidation

FeOOH with excellent catalytic properties for oxygen evolution and also considered to be a true active site has attracted great interest in recent years. However, the intrinsic low conductivity limits its catalytic performance. Herein, a one-dimensional core-shell NiMoO₄/FeOOH heterojunction with high OER activity and stability was developed. At current densities of 10 and 100 mA cm^-2, low overpotentials of 194 and 266 mV are need to drive oxygen evolution, meanwhile, the electrode exhibits high catalytic kinetics with small Tafel slopes of 53.4 mV dec^-1 and excellent stability over 100 hours. Further analysis showed that the ultrathin FeOOH layer (~5 nm) uniformly covered the surface of NiMoO₄ nanorods, acting as an active species and facilitating the surface change transfer to the interior. The internal NiMoO₄ cores, on the other hand, provides reliable electron transmission as a highly conductive medium, and can effectively overcome the low conductivity of FeOOH. DFT calculations further manifest the strong electronic interactions between NiMoO₄ and FeOOH species. The NiMoO₄ core serves as mass transport of active materials is beneficial to tune the adsorption energy of OH^- on the surface of electrocatalysts.