Influence of heat treatment process on photocatalytic activity of photocatalyst TiO₂/TiC_xO_y coatings during heat treatment in carbon powder

Photocatalyst TiO₂/TiC_xO_y coatings on alumina (Al₂O₃) balls had been successfully fabricated by mechanical coating technique with titanium (Ti) powder and subsequent heat treatment in carbon powder. The influence of heat treatment conditions in carbon powder on the formed compounds, surface morphology and photocatalytic activity of photocatalyst TiO₂/TiC_xO_y coatings was investigated. XRD results show that the compounds of TiC_xO_y and TiO₂ were formed on the surface of Ti coatings during heat treatment in carbon powder. The relative amounts of TiC_xO_y and TiO₂ remarkably varies with changing the heat treatment temperature and/or holding time. The formed nano-bump structure during heat treatment in carbon powder at 1073 or 1173 K, could increase the accessible surface area. The formation of Ti³⁺ and generated oxygen vacancies confirmed by XPS measurement, are in favor of narrowing band gap to enhance the visible-light photocatalytic activity of photocatalyst TiO₂/TiC_xO_y coatings. The photocatalytic activity of the sample by heat treatment in carbon powder at 1173 K for 15 h shows highest. The fabrication strategy provides us a facile preparation procedure of visible-light responsive photocatalyst coatings.