A one-step preparation and enhanced electrochemical properties of C-TiO2 composite films

Abstract

In order to improve the capacitive properties of TiO2 materials for supercapacitors, the carbon-modified TiO2 (denoted as C-TiO2) composite films was synthesized by gas thermal penetration of pure Ti plate with methanol as the drop agent under the temperature of 550°C. The structure and composition of C-TiO2 was investigated by SEM, XRD, RAMAN, XPS and XANES. The electrochemical performance of C-TiO2 was evaluated by electrochemical impedance spectra (EIS), cyclic voltammetry (CV) and galvanostatic charge/discharge (GCD) tests. Results show that the film is composed of a large amount of rutile TiO2 and a little anatase TiO2, and meantime the carbon is deposited on the film through the methanol decomposition during the gas thermal penetration, which greatly influences the electrochemical properties of the composite films. The prepared C-TiO2 yields the largest specific capacities of 47.46mCcm−2 at the scan rate of 10mVs−1 based on the CV curves, and 7.35mCcm−2 at the current density of 0.075mAcm−2 based on the galvanostatic charge/discharge curves, which compares favorably with many other similar modified TiO2 film materials reported nowadays. The excellent large charge storage properties of C-TiO2 films are attributed to the deposition of a certain amount of graphitized carbon and organic carbon containing hydroxyl groups and carbanyl groups and the formation of Ti3+ in the form of TiO1.5 under methanol reductive atmosphere be means of the improvement of the pseudocapacitance property and the conductivity of the composite films.