Synthesis of Co4S3/Co9S8 nanosheets and their Fe/Cr dual heteroatom co-doped components for the promoted OER properties

Co 4 S 3 /Co 9 S 8 nanosheets, Co-based sulfides with mixed crystalline phase, were first successfully prepared via solvothermal approach combined with ultrasonic exfoliation. Fe 3+ ions were then doped into the Co 4 S 3 /Co 9 S 8 nanosheets to form Fe-doped Co 4 S 3 /Co 9 S 8 by a simple one-step impregnation method. The results of oxygen evolution reaction (OER) activities in alkaline media show that the Fe 3+ doping can significantly reduce the oxygen evolution overpotential and Tafel slope, and the optimum feeding mole ration of Fe/Co is 30%. Following that, Cr 3+ ions were further doped into 30% Fe-doped Co 4 S 3 /Co 9 S 8 nanosheets to form bimetallic heteroatom co-doped dopant. Compared with the undoped, Fe-doped, and Cr-doped Co 4 S 3 /Co 9 S 8 nanosheets, the testing of OER activity implies that Fe/Cr co-doped Co 4 S 3 /Co 9 S 8 nanosheets have the most excellent electrocatalytic properties with a overpotential of 350 mV at ƞ 10 and a small Tafel slope of 39.72 mV dec −1 , and have an outstanding stability. Both the OER performance and stability decreased by the order of Fe/Cr co-doped Co 4 S 3 /Co 9 S 8 nanosheets > Fe (Cr)-doped Co 4 S 3 /Co 9 S 8 nanosheets > undoped Co 4 S 3 /Co 9 S 8 nanosheets, the enhanced mechanisms of which were investigated by XPS, XRD, and SEM.