Preparation of high-concentration substitutional carbon-doped TiO(2) film via a two-step method for high-performance photocatalysis

In this paper, we present a facile two-step method for preparing a high-concentration substitutional carbon-doped TiO(2) (TiO(2−x)C(x)) film. First, the titanium substrate undergoes gas carburizing, followed by micro-arc oxidation (MAO) to form a carbon-doped TiO(2) film on the surface. The process can be described as direct oxidation of titanium carbide (O→TiC(x)). The experimental results reveal that compared with traditional thermal annealing, this process could increase the carbon doping concentration to 6.07 at% and x to 0.24 in TiO(2−x)C(x). The TiO(2−x)C(x) film exhibits a significant red-shift in the band-gap transition, a narrow band gap of 2.77 eV, and excellent photocatalytic performance, more than two times higher than that of undoped TiO(2) film. This method is simple, efficient, economical, environmentally friendly, and adapts to mass production. This experimental strategy can also be used in preparing other doped elements.