Synthesis of amorphous carbon coated on V2O3 core-shell composites for enhancing the electrochemical properties of V2O3 as supercapacitor electrode

Abstract

V2O3@C core-shell composites were successfully synthesized by the heat treatment with H2V3O8@C core-shell composites. The composition and phase of the samples were evaluated by X-ray powder diffraction, energy-dispersive X-ray spectrometer, X-ray photoelectron spectroscopy, elemental analysis, infrared spectroscopy and Raman spectroscopy. The morphology and structure of the samples were observed by the means of scanning electron microscopy and transmission electron microscopy. The results revealed that the samples consisted of the crystal V2O3 phase and the amorphous carbon phase, and their morphology were well-defined core-shell nanobelts, and each V2O3 core was encapsulated into amorphous carbon. The Brunauer-Emmet-Teller result showed that V2O3@C core-shell composites displayed the specific surface area as high as 83.2m2g−1. Furthermore, the electrochemical properties of V2O3@C core-shell composites as supercapacitor electrode were investigated by cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy. For comparison, the synthesis and electrochemical properties of carbon spheres and V2O3 particles were also investigated. The results showed the measured capacitance of V2O3@C core-shell composites was based on the pseudocapacitance. V2O3@C core-shell composites displayed the highest specific capacitance and electric conductivity among carbon spheres, V2O3 particles and V2O3@C core-shell composites. The specific capacitances were 223, 180, 146, 112, 92 and 72 Fg−1 at the discharge current densities of 0.1, 0.5, 1, 2, 5 and 10 Ag−1, respectively. The present work provided a strategy to prepare core-shell structured composites of metal oxides with improved electrochemical performance for supercapacitor electrodes.