Fabrication of Carbon Modified Visible Light Active n-TiO₂ Thin Films by Wet Process for Photoelectrochemical Water Splitting

Abstract

Carbon modified (CM)-n-TiO 2 exhibited reduced bandgap energy and improved photoresponse. In this study, the CM-n-TiO 2 films of different carbon contents were made by spray pyrolysis from glucose containing TiCl 4 solution and subsequent calcination. It was found that the CM-n-TiO 2 films exhibit significant dependence of photocurrent on their carbon contents, and carbon doping reduced the bandgap energy of TiO 2 from 3.2 eV to 2.78 eV and created a new energy band having bandgap of 1.45 eV within its intrinsic bandgap. Furthermore, the photocurrent responses both in UV and visible regions were found to be enhanced by increasing the amount of doped carbon in these films. It was proposed that the increased carbon doping density in the TiO 2 thin films increases the density of states of the midgap band, thereby enhancing the photocurrent responses in the UV and visible region.