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.