Preparation of high-concentration substitutional carbon-doped TiO2 film via a two-step method for high-performance photocatalysis

Abstract

In this paper, we present a facile two-step method for preparing a high-concentration substitutional carbon-doped TiO₂ (TiO_2−xC_x) film. First, the titanium substrate undergoes gas carburizing, followed by micro-arc oxidation (MAO) to form a carbon-doped TiO₂ 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−xC_x. The TiO_2−xC_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 TiO₂ 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.