High-performance supercapacitor enabled by vacancy engineering of Fe2O3@reduced graphene oxide matrix

The construction of Fe2O3 with oxygen vacancy on the reduced graphene oxide matrix (Fe2O3-OV@rGO) is proposed under hydrothermal reduction environment for high-performance asymmetric supercapacitors. The obtained Fe2O3-OV@rGO displays strong mechanical property and ultra-light weight. The transmission electron microscopy images of Fe2O3-OV@rGO present that Fe2O3 nanoparticles with the size of 30 nm are uniformly distributed on the rGO matrix. Cyclic voltammetry tests indicate that capacitance contribution is dominant relative to diffusion contribution. The Fe2O3-OV@rGO shows the specific capacitance of 1291.5 F<middle dot>g(-1) at 0.5 A<middle dot>g(-1) and capacitance retention of 72 % from 0.5 to 10 A<middle dot>g(-1). In-situ Raman spectra of Fe2O3-OV@rGO are recorded to trace OV concentration change, suggesting its excellent electrochemical reversibility. An asymmetric supercapacitor Fe2O3-OV@rGO||rGO exhibits an ultrahigh energy density of 115.6 Wh<middle dot>kg(-1) at a power density of 140 W<middle dot>kg(-1). A 94.7 % capacitive retention and a similar to 100 % Coulombic efficiency remain after 20,000 cycles. Ideal supercapacitive behaviors of the Fe2O3-OV@rGO||rGO are attributed to the creation of OVs in the Fe2O3 lattice structure and the construction of conducting channels stemmed from the rGO.