Interfacial engineering of NiS/NiMoO4 nanorod arrays to improve OER and HER performance for stable overall water splitting

The development of highly efficient and stable OER and HER bifunctional catalysts is important for sustainable energy conversion. Interfacial engineering is one of the most effective strategies to modulate the electronic structure of the active center to enhance the catalytic activity. Therefore, in this paper, NiMoO₄ nanorods grown on nickel foam were annealed and etched to enable the formation of α-NiMoO₄, β-NiMoO₄ and NiS phases on the surface of the nanorods. This method enables controlled phase transformation and etching of the nanorod surface. As a bifunctional catalyst, NiS/NiMoO₄ performs excellently, requiring only 270 mV and 270 mV overpotentials to reach 100 mA cm^-2 for OER and HER, respectively. Excellent durability was demonstrated in a two-electrode electrolytic cell stability test at 100 mA cm^-2 for 200 h. This study suggests a rational approach to interfacial design for improving catalyst activity.