Synthesis and catalytic mechanism for NiS/NiS2/NC nanoparticles towards oxygen reduction reaction and oxygen evolution reaction

The advancement of efficient and environmentally viable bifunctional electrocatalysts, capable of facilitating both the oxygen reduction reaction and oxygen evolution reaction, assumes a pivotal role in driving the com-mercial progression of metal-air batteries. This research employs the low-temperature molten salt template method to fabricate the NiS/NiS2/NC catalyst in an atmosphere devoid of noble gasses protection. BET char-acterization indicates that the composite of NiS/NiS2 and NC can enhance the specific surface area and effec-tively enhancing the reactive sites. The NiS/NiS2/NC catalyst exhibits remarkable bifunctional catalytic prowess in 1 M KOH electrolyte, manifesting a half-wave potential of 0.871 V and an overpotential of 195 mV for the OER at a current density of 10 mA cm-2. Moreover, the NiS/NiS2/NC catalyst demonstrates outstanding electro-chemical stability. Furthermore, density functional theory calculations have substantiated a cooperative influ-ence arising from the interaction between NiS2 and NC, which engenders a significant advancement in the bifunctional catalytic activity of the synthesized composite. These findings provide a novel avenue and theo-retical insight for the design and synthesis of advanced bifunctional electrocatalysts.