NiS nanostrips@FeNi-NiFeO nanoparticles embedded in N-doped carbon microsphere: An improved electrocatalyst for oxygen evolution reaction.

The designing and preparing of low-cost and easily available electrocatalyst for oxygen evolution reaction (OER) are crucial for many advanced energy technologies. Herein, the NiS nanostrips@FeNi-NiFeO nanoparticles embedded in N-doped carbon (NiS@FeNi-NiFeO/C) microspheres were synthesized as improved electrocatalyst for OER, using a facile heat-treatment method. The optimized NiS@FeNi-NiFeO/C-3 sample exhibits enhanced electrocatalytic activity toward OER performance with an overpotential of 280 mV at 10 mA cm and a small Tafel slope of 33.9 mV dec. Furthermore, NiS@FeNi-NiFeO/C-3 composite shows good stability in alkaline media. The outstanding electrocatalytic OER performance of composites was attributed due to the synergetic effect between NiS nanostrips and FeNi-NiFeO nanoparticles and it is believed that the heterointerfaces between them act as active centers for OER. Additionally, N-doped carbon prevents the aggregation of NiS@FeNi-NiFeO species and enhances the conductivity of composites during the OER process.