Enhanced Photocatalytic Activity of TiO2 Coatings by Heat Treatment in Carbon Powder

The heat treatment in carbon powder is a safe and effective strategy to enhance the photocatalytic activity of titanium dioxide (TiO₂) coatings. Firstly, Ti coatings were prepared by mechanical coating operation with Ti powder on alumina balls. Secondly, the target TiO₂ coatings were prepared using the prepared Ti coatings by the multi-heat treatment (pretreatment in carbon powder, oxidation in air and reduction in carbon powder). During the pretreatment, thin films of Ti₂CO and micro-cracks form in the surface of the Ti coatings. The formed thin films and micro-cracks are helpful for forming a nano-fiber morphology of rutile TiO₂, during the subsequent oxidation. During the reduction, oxygen vacancies generated in the lattice of rutile TiO₂ are in favor of narrowing the band gap. The target TiO₂ coatings with a nano-fiber morphology and the narrowed band gap, effectively enhances the photocatalytic activity by more than 3 times, compared with the pristine TiO₂ coatings.