Hui Zhao,Jihai Duan,Pengxia Sun,Zisheng Zhang,Weiwen Wang
Black Ti 3+ self-doping TiO 2 nanotubes (BTNT) have attracted widespread attention due to their abilities to enhance visible light response and photo-generated electron-hole separation without introducing impurity particles. However, due to the poor stability of Ti 3+ , the doping of a large amount of Ti 3+ is a huge challenge. In this work, we have taken a different approach, and the black Ti 3+ self-doping TNT-Ag-WO 3 (BAW) photocatalyst was prepared. The BAW Z-scheme photocatalytic (PC) system was successfully constructed. Compared with TNT's PC system (degrade 40.56%), BAW Z-scheme PC system can degrade 97.67% with 20 mg/L MB wastewater after 120 min. By introducing a large number of Ti 3+ and O vacancies, the inherent active group is mainly converted from the holes and.OH on the WO 3 valence band and.O 2 − on the TiO 2 conduction band , which improved the stability of O vacancies.Before and after the reaction, the reduction of Ti 3+ in BTNT is about 30 times that of Ti 3+ in BAW. This work provides a reference and basis for constructing Z-scheme heterojunction on BTNT, and also provides new ideas for improving the stability of Ti 3+ and O vacancies in self-doped TiO 2 .
Ti 3+ self-doped single-crystalline SrTiO 3−x nanocubes acting as molecular bricks are successfully assembled onto Ti 3+ self-doping single-crystalline TiO 2−x (B) nanorods through an effortless two-step hydrothermal process coupled with an in situ solid-state chemical reduction method. SrTiO 3−x nanocubes act as molecular bricks, which are uniformly assembled onto the surface of TiO 2−x (B) nanorods due to lattice matching. The band gap of the resultant SrTiO 3−x /TiO 2−x (B) sample is ∼2.97 eV, which exhibits excellent photocatalytic performance for the reduction of Cr(VI) and hydrogen production under visible light. The apparent rate constant k value for the photocatalytic reaction of SrTiO 3−x /TiO 2−x (B) for Cr(VI) reduction is ∼8 times higher than that of white TiO 2 (B). The photocatalytic hydrogen production rate for SrTiO 3−x /TiO 2−x (B) is ∼160.2 μmol g −1 h −1 , which is ∼5 times higher than that of white TiO 2 (B). The enhanced photocatalytic activity can be considered to be caused by a synergetic effect of heterojunction formation and the introduction of Ti 3+ self-doping, which can not only facilitate the separation of photogenerated charge carriers between TiO 2−x (B) and SrTiO 3−x , but also broaden the photoresponse from the UV to visible-light region.
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