Hydrogenated nanoporous TiO₂ film on Ti−25Nb−3Mo−2Sn−3Zr alloy with enhanced photocatalytic and sterilization activities driven by visible light

Anatase TiO₂ film with highly-ordered nanoporous structure was successfully synthesized on Ti−25Nb−3Mo−2Sn−3Zr (TLM) alloy through a simple two-step anodization method and a subsequent hydrogenated process. The results show that the obtained TiO₂ film on TLM alloy presents a thickness of 900 nm and contains numerous oxygen vacancies. Furthermore, the concentration of oxygen vacancies can be tuned by controlling the temperature of hydrogen annealing. Through the first-principles calculations, it is found that the presence of oxygen vacancy can effectively narrow the band gap of TiO₂ and thus expand light absorption range of TiO₂ to visible light. The sample hydrogenated at 400 °C displays good photocatalytic and photocatalytic sterilization activities, which can be ascribed to the special structure, enhanced crystallinity and oxygen vacancies content of TiO₂ film. These features make the material a good candidate in practical application. - Highlights: • Well-bonded and nanoporous TiO₂ film on TLM alloy was successfully prepared using a modified two-step anodization. • The content-controlled oxygen vacancies are introduced into TiO₂ via hydrogen annealing. • The obtained sample displays good photocatalytic and sterilization activities under visible-light irradiation.