Facile synthesis of Co/Fe bimetallic doped Ni3S2 nanosheets and supercapacitor performance

Ni3S2 is an outstanding electrode material due to its high theoretical specific capacity, however, in practical research, the higher theoretical capacity is difficult to show, and the change of the structure in the cycling process affects the cycling stability, which limits its practical application. To address these issues, this study presents a strategy to synthesize Fe and Co bimetallic doped Ni3S2 nanosheets on nickel foam (NF) surface. This strategy introduces bimetallic atoms quickly and easily while synthesizing nanosheet structures, and the resulting synergistic interactions between the bimetals and the mutual support effect of the nanosheets can effectively enhance electron transfer and improve cycling stability. The electrochemical results show that the Fe and Co-doped sample (Ni3S2-Co/Fe-5) exhibits a specific capacitance of 3351 F center dot g- 1 at 1 A center dot g- 1 in the three-electrode system, which is nearly five times higher than the specific capacity of the undoped Fe and Co- doped sample (Ni3S2), and the capacity retention rate after cycling 5000 cycles at a current density of 10 A center dot g- 1 is 100 %, the prepared sample (Ni3S2-Co/Fe-5) was assembled with activated carbon (AC) to form a hybrid supercapacitor, which could provide a maximum power density of 9818 W center dot kg-1, a maximum energy density of 66.25 Wh center dot kg-1, and a capacity retention of 94.5 % after 10,000 cycles, with a capacity loss of only 5.6 %.