Influence of carbon atmosphere on surface morphology and photocatalytic activity of TiO_2 coatings by multi-heat treatment

摘要

Photocatalyst titanium dioxide (TiO_2) coatings on alumina (Al_2O_3) balls had been prepared by mechanical coating technique with titanium (Ti) powder and multi-heat treatment (pretreatment-oxidation-reduction). The influence of carbon atmosphere during multi-heat treatment on the surface structure and photocatalytic activity of TiO_2 coatings was investigated and characterized. Results show that thin coatings of TiO_2 and Ti_2CO form on the surface of Ti coatings during pretreatment in air or in carbon atmosphere, respectively. Due to the pretreatment, different surface morphologies of rutile TiO_2 form on the surface of Ti coatings, during subsequent oxidation in air. Oxygen vacancies are generated in the lattice of rutile TiO_2, during subsequent reduction in carbon atmosphere. The photocatalytic activity of the TiO_2 coatings prepared by multi-heat treatment is effectively enhanced, compared with the TiO_2 coatings prepared by solo-oxidation of Ti coatings. The visible light photocatalytic activity of TiO_2 coatings Heated in carbon atmosphere could be effectively enhanced by more than eight times. The photocatalytic activity under ultraviolet is more related with nano-fiber morphology, while the photocatalytic activity under visible light is related with the narrowed band gap.