To unveil the role of Ti3+ defects in photocatalysis, a facile and efficient method is highly desirable to manage the distribution and concentration of Ti3+, and consequently, understand their impact on the defects-induced visible-light photoactivity. In this BIX 02565 work, we have developed an innovative facial oxidation-based solvothermal method to synthesize bulk Ti3+ self-doped anatase TiO2 nanocrystals (TiO2−x). The distribution of subsurface/bulk defects can be controlled by further annealing the as-prepared TiO2−x at different temperatures. Based on experimental observations, we first propose a “Ti3+ reversible-diffusion mechanism”, demonstrating that “Ti3+”-induced photoactivity relies on not only the absolute defect concentration, but also on a proper distribution of the subsurface/bulk defects.
Titanium hydride (TiH2, 98.0%) powder was purchased from Sigma–Aldrich Co., LLC. Hydrogen peroxide (H2O2, 30.0%), sodium borohydride (NaBH4, 98.0%), absolute ethyl alcohol (EtOH, 99.9%), hydrochloric acid (HCl, 36–38%, A.R.) and sodium hydroxide (NaOH, 98%, A.R.) were obtained from Sinopharm Chemical Reagent Co., Ltd. and used as received without any further purification. Double distilled water was used throughout the experiments.