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

- A binder-free C-TiO2 composite film was prepared by gas thermal penetration on pure Ti plate.
- C-TiO2 composite films yields the largest specific capacity of 47.46 mC cm−2 at the scan rate of 10 mV s−1.
- C-TiO2 composite films yields the largest specific capacity of 7.35 mC cm−2 at the current density of 0.075 mA cm−2.
- Drop agent methanol provides the compounded carbon material for the film.
- Gas thermal penetration provides an ideal reductive atmosphere for the formation of Ti3+ ions.

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 47.46 mC cm−2 at the scan rate of 10 mV s−1 based on the CV curves, and 7.35 mC cm−2 at the current density of 0.075 mA cm−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.