Solvothermal synthesis of CoCeSx quantum dots based on Bi-pyrene-terminated molecular wires modified porous graphene for high performance supercapacitors

Abstract

Transition metal quantum dots (QDs) have attracted enormous attention in the field of energy storage in recent years due to their unique nano-size effect and flexible surface functionalities. It is worth noting that the aggregation of QDs will lead to the decline of electrochemical performance, so it is necessary to maintain its good dispersion stability. Bi-pyrene-terminated molecular wires (BPMW) can reduce the stacking of graphene, which is considered to be a good material for modifying graphene with desired porous structure, higher specific surface area, and more attachment sites for the loading of QDs. Here, rGO@BPMW@CoCeSx-QDs were successfully designed and constructed. In detail, CoCe bimetallic organic framework (CoCe-MOF) was grown in situ on BPMW modified graphene by two-step solvothermal method to afford porous composites of rGO@BPMW@CoCeSx-QDs (pore size range is 40–230 nm). The fabricated electrode based on rGO@BPMW@CoCeSx-QDs shows an excellent electrochemical capacitance of 1047 F g−1 at the current density of 1 A g−1 in a three-electrode system. Moreover, a solid-state asymmetric supercapacitor (ASC) device can be fabricated based on the synthesized rGO@BPMW@CoCeSx-QDs, and exhibits a high energy density of 32.3 Wh kg−1 at a power density of 750 W kg−1.