Fabrication of oxygen-deficient TiO2 coatings with nano-fiber morphology for visible-light photocatalysis

In this study, heat treatment in carbon powder is developed as a safe, simple, and effective strategy to fundamentally enhance the visible-light photocatalytic activity of titanium dioxide (TiO2) coatings. The target TiO2 coatings were fabricated using the prepared Ti coatings by a heat treatment process involving pretreatment in carbon powder, followed by oxidation in air, and reduction in carbon powder. The results show that Ti2CO coatings are formed and micro-cracks appear in the surface of the coatings during pretreatment. The Ti2CO coatings and micro-cracks are beneficial for forming rutile TiO2 coatings with nano-fiber morphology during subsequent oxidation. During reduction, oxygen vacancies, which promote the narrowing of band gap, are generated in the lattice of rutile TiO2. The visible-light photocatalytic activity of the target TiO2 coatings is effectively enhanced more than 8 times, compared with the TiO2 coatings prepared solely by oxidation of Ti coatings. The ability to fabricate highly visible-light photoactive TiO2 materials by simple and safe heat treatment in carbon powder opens up new opportunities in various areas, such as the preparation of powders, nanowires, films.