Rough Ni@MoN corals for the hydrogen evolution reaction in acidic and alkaline media

Abstract

The development of noble-metal-free electrocatalysts with high catalytic efficiency, low cost, and high durability in pH-universal media is encountering a bottleneck in practical applications. In this paper, Ni@MoN-700 coral hybrids were prepared using hydrogen evolution reaction (HER) catalysts, which were synthesized by a high-temperature reduction of NiMoO₄ nanorods with urea. It was found that the annealing temperature seriously affects the surface morphology and chemical composition of the catalysts. Besides, structural reorganization occurred during the HER, which involved the joining of pyrrolic N, metal nitrogen, Mo³⁺, and Mo⁶⁺, governing the HER performance. Also, during the HER, Ni and Mo could synergistically improve the overall catalytic activity of the catalysts, via electronic interactions. These advantages endow Ni@MoN-700 with exceptional endurance and great HER activity, with a low overpotential of 30 mV and 76 mV at 10 mA cm⁻² in alkaline and acidic media. These characteristics are similar to those of Pt under alkaline conditions. NiMoN catalysts show unusual activity and long-term stability, indicating a wide range of potential applications.