A novel Ni3S2/MnO2@N,F-CQDs composite with spherical-chain-like morphology for efficient oxygen evolution reaction in aqueous alkaline solutions

Developing earth-abundant transition metal-based oxygen evolution reaction (OER) electrocatalysts is extremely essential for accomplishing efficient electrocatalytic overall water splitting. Herein, we synthesized a Ni3S2/MnO2@N,F-CQDs catalyst with a microstructure composed of interlaced nanowires in a spherical-chain shape by treating a nickel foam substrate with sulfur and co-regulating the morphology and properties of manganese dioxide with carbon dots. The catalyst exhibited excellent OER electrocatalytic performance and stability under alkaline conditions, requiring only a low overpotential of 226 mV at 10 mA cm-2 and a Tafel slope of 105.76 mV dec-1. Furthermore, the catalyst remained stable after 3000 cycles of Cyclic Voltammetry (CV) testing and multistep chronopotentiometric (CP) measurements at the current density of 10, 50 and 100 mA cm−2 for 12 h, respectively. The enhanced performance of Ni3S2/MnO2@N,F-CQDs catalyst was mainly attributed to the practical improvement of charge interface transport performance induced by carbon dots and interface layer Ni3S2 which increased active catalytic sites of the electrode and reduced charge transfer resistance. These results suggest a promising approach for developing efficient OER electrocatalysts.