Visible Light Photoelectrochemical Response of Carbon- Doped TiO2 Thin Films Prepared by DC Reactive Magnetron Sputtering

Carbon-doped TiO2 thin films were prepared by direct current (DC) reactive magnetron sputtering at room temperature in Ar/O2 ambience, using a titanium target incrusted with graphite pieces. The films as prepared were characterized by X-ray diffraction (XRD), UV-Vis transmission spectra, and photoelectrochemistry methods. The XRD patterns of the films showed that the doping of carbon was beneficial to the crystallization of the films. When the ratio of area of C/Ti was less than 0.10, the crystallization of the films increased with the increase in graphite area in the target. The band gap of the films decreased from 3.4 eV (pure TiO2 films) to 3.1 eV when the ratio of area of C/Ti in the target was 0.05. The photoelectrochemical property of the films improved when the ratio of area of C/Ti in the target was less than 0.10. When this ratio was 0.10, the photocurrent density of the films was 0.069 μA·cm−2 at 0 V under visible light illumination. However, an abnormal photoelectrochemical response was observed when the ratio of area of C/Ti in the target was 0.16.