Oxygen Vacancy Defect Engineering of Heterophase Junction TiO 2 : Interfacial/Surface Oxygen Vacancies Coadjust the Photocatalytic ROS Production

In this study, TiO 2 samples are synthesized through two stages including hydrolysis and calcination. It is found that the addition of HCl in the hydrolysis stage could facilitate the formation of heterophase junction TiO 2 . By annealing at 300 °C in an argon atmosphere, interfacial oxygen vacancies (Vo) and surface Vo (distributed in the anatase phase) can be constructed in the heterophase junction TiO 2 . After photocatalytic experiments, it can be found that surface Vo and interface Vo have a synergistic effect in the production of photocatalytic reactive oxygen species (ROSs). Surface Vo can enrich O 2 and transmit electrons to O 2 on the surface of anatase. Therefore, the enriched O 2 can be converted into • O 2 – and 1 O 2 easily. The interfacial Vo not only facilitate the electron transmission between the two phases but also change the electron transfer mode from I-scheme to Z-scheme. Thus, interfacial Vo make photogenerated electrons transfer to anatase and photogenerated holes leave in the rutile. These holes in the rutile part have high oxidation potential and can better oxidize H 2 O (or OH – ) molecules to • OH. They can also oxidize • O 2 – to 1 O 2 . This work promotes the further development of defect design and application in photocatalytic materials.