Mixed-Phase TiO2 with Oxygen Vacancies for Enhanced Visible Light Photocatalysis Performance

Because of the decrease in the band gap and the carrier recombination rate, the visible light photocatalysis performance of the mixed-phase TiO2 with oxygen vacancies is better than that of the pure-phase TiO2. In this study, two different acids were separately applied in the hydrothermal synthesis of TiO2 nanoparticles without any post-heat treatment. The reaction was carried out at a relatively low temperature not exceeding 140(circle)C. Both kinds of crystallized TiO2 powders show much more band gap reduction than that of commercial Degussa P25 TiO2 nanoparticles, which can be attributed to the oxygen vacancies. Under the visible light illumination-assisted photocatalytic degradation of methyl orange in water, the two mixed-phase TiO2 powders exhibited a steady photocatalytic activity upon increasing to five cycles. The highest photocatalytic efficiency of the two powders is 2.7 times than that of the P25 powder, which is regarded as an excellent photocatalyst for water purification. Mixed-phase TiO2 nanoparticles were synthesized by acid-assisted hydrothermal synthesis at 140(circle)C without any post-calcination. Compared with P25, the specific surface area of H-TiO2 (by HCl) and A-TiO2 (by acetic acid) is larger. At the same time, H-TiO2 and A-TiO2 have excellent photocatalytic performances when assisting in the degradation of methyl orange in water under visible light illumination. The stable high photocatalytic performance and the simple preparation methods of the H-TiO2 and A-TiO2 nanoparticles will promote the industrial application.