Multiphase Heterostructure Engineering and Theorical Aspects of a Hierarchical Nanostructure NiFe-NS/NiMoO4 Array Enabling Efficient Oxygen Evolution Reaction in Alkaline Media

The design of multiphase heterostructures presents a promising strategy for oxygen evolution reaction (OER) and serves as an effective approach to constructing efficient alkaline OER catalysts. In this paper, the OER catalyst with a NiFe-NS/NiMoO4 layered heterostructure was synthesized by reflux condensation and hydrothermal methods. The unique rock-like nanospheres can increase the specific surface area and provide more active sites. The formation of heterojunctions through the modification of NiFe nanospheres on NiMoO4 nanorods can induce changes in their electronic structure. Due to its inherent properties, NiFe-NS/NiMoO4 demonstrates higher performance than commercial RuO2 (which has an overpotential of 228 mV at a current density of 10 mA cm–2), with overpotentials of 196 and 294 mV at current densities of 10 and 100 mA cm–2, respectively. The stability of the sample was proved to be excellent during a 50 h stability test. Density functional theory (DFT) calculations also indicate that the improved efficiency of the OER can be attributed to controlling and adjusting of the electron structure through heterojunction formation as well as the collaborative impact resulting from NiFe and NiMoO4. The structure enables optimized adsorption of intermediates and facilitates the kinetics of OER, and provides an idea for the design of heterogeneous catalysts.