Defective TiO2 prepared via synchronous crystallization and constraint reduction strategy with enhanced photocatalytic activity

Defects (oxygen vacancy and Ti3+) play crucial roles in determining band structure, light absorption, and catalytic activity of TiO2. Herein, a synchronous crystallization and constraint reduction strategy was reported to construct controllable defective TiO2 using sodium borohydride (NaBH4) as the reductant. The constraint decomposition effect of NaBH4 in pore channels of TiO2 aerogels enables the defects migrate from surface to bulk region effectively, and bulk defects are more stable. Moreover, the species and concentration of defects can be controlled by changing the calcination temperature in this case. An optimum temperature for the NaBH4 treatment was found to be 500 degrees C. After the reduction at 500 degrees C, defective TiO2 with maximum bulk oxygen vacancies shows excellent visible light absorption performance, effective separation of photogenerated charge carriers, and suitable band edge, and the removal rate was 94.9% for rhodamine B (RhB) under visible light which was about 325% higher than that of TiO2 without oxygen vacancy.

Automated summary

Defects (oxygen vacancies and Ti3+) in TiO2 play crucial roles in determining band structure, light absorption, and catalytic activity. A strategy involving simultaneous crystallization and constraint reduction using NaBH4 as the reductant was reported to construct controllable defective TiO2. This approach enables defects to migrate effectively from the surface to the bulk region, with bulk defects being more stable. By adjusting the calcination temperature, the species and concentration of defects can be controlled, with an optimal temperature of 500 degrees Celsius found for NaBH4 treatment. Defective TiO2 treated at 500 degrees Celsius shows enhanced visible light absorption performance and a significantly higher removal rate of rhodamine B compared to TiO2 without oxygen vacancies.