Grafting Cobalt Diselenide on Defective Graphene for Enhanced Oxygen Evolution Reaction

Cobalt diselenide (CoSe₂)has been demonstrated to be an efficient and economic electrocatalyst for oxygen evolution reaction (OER)both experimentally and theoretically. However, the catalytic performance of up-to-now reported CoSe₂-based OER catalysts is still far below commercial expectation. Herein, we report a hybrid catalyst consisting of CoSe₂ nanosheets grafted on defective graphene (DG). This catalyst exhibits a largely enhanced OER activity and robust stability in alkaline solution (overpotential at 10 mA cm⁻²: 270 mV; Tafel plots: 64 mV dec⁻¹). Both experimental evidence and density functional theory calculations reveal that the outstanding OER performance of this hybrid catalyst can be attributed to the synergetic effect of exposed cobalt atoms and carbon defects (electron transfer from CoSe₂ layer to defect sites at DG). Our results suggest a promising way for the development of highly efficient and low-cost OER catalysts based on transition metal dichalcogenides.