Flower-like Fe2O3@multiple graphene aerogel for high-performance supercapacitors

The paper reports one strategy for synthesis of flower-like Fe2O3@ multiple graphene aerogel (F-Fe2O3@MGA). First, Fe3+ was combined with 2-methylimidazole in an ethylene glycol medium containing polyvinyl pyrrolidone surfactant to form Fe(III)-2-methylimidazole complex. Due to the template effect of polyvinyl pyrrolidone, the complex shows a flower-like morphology that consists of ultrathin Fe2O3 plates. Then, Fe3+ in the complex was oxidized into F-Fe2O3 in air at 350 degrees C for 2 h and at 500 degrees C for 0.5 h. Finally, the F-Fe2O3 was hybridized with graphene via a multiple gelation method. The as-prepared F-Fe2O3@MGA gives well-defined three-dimensional structure. The F-Fe2O3 crystals are well dispersed on the dense graphene frameworks networks. The unique structure achieves to high electron/ion conductivity and structural stability. The composite electrode for supercapacitors exhibits a high specific capacitance (1119 F g(-1) at the current density of 1 A g(-1)) and high rate-capability (630 F g(-1) at the current density of 10 A g(-1) and 492 F g(-1) at the current density of 20 A g(-1)) in a 3.0M KOH electrolyte. The asymmetric supercapacitor of F-Fe2O3@MGA/activated carbon provides the energy density of 95.3Wh kg(-1) at the power density of 800Wkg(-1) and 45Wh kg(-1) at the power density of 8000 Wkg(-1). The outstanding capacitive performance makes F-Fe2O3@ MGA can be used as an electrode material for next-generation high-performance supercapacitors. (c) 2018 Elsevier B.V. All rights reserved.