A rGO/Cu0.7Fe0.3S2 composite electrode for asymmetric supercapacitor prepared via MIL-101 template strategy

Abstract

As a branch of MOF, MIL has attracted much attention in the field of electrochemistry because of its high porosity and potential high charge storage capacity. Graphene oxide is considered as an ideal supercapacitor material because of its high electrical conductivity, high specific surface area and rich surface functional groups. The metal sulfides prepared with MIL as template not only inherit the structural characteristics of MIL, but also improve the electrical conductivity of the materials, which thus show excellent energy storage properties. In this work, the rGO/Cu0.76Fe0.24S2 composite was prepared through in-situ growth of MIL-101 on the surface of GO followed by copper nitrate etch, high temperature carbonization and hydrothermal sulfurization. To the best of our knowledge, it is the first time to report that rGO/Cu0.7Fe0.3S2 is used as the electrode of supercapacitor and tested for energy storage. The optimized rGO/Cu0.7Fe0.3S2 electrode exhibited good capacitive performances, including high specific capacitance of 661.2 F g−1 at 1 Ag−1 and remarkable cycle stability with 69 % after 5000 cycles. Employing the as-prepared rGO/Cu0.7Fe0.3S2 composites as positive electrode, the hybrid supercapacitor device displayed spectacular capacity of energy density (54.37 Wh kg−1), great power density (887.75 W kg−1) and impressive long-term stability of 70 % retention after 5000 cycles. The results show that the composite prepared with graphene oxide as substrate and MIL-101 (Fe) as template should be a promising materials for fabricating high-performance supercapacitor.