Role of defects on TiO 2 /SiO 2 composites for boosting photocatalytic water splitting.

Defect engineering of semiconductor photocatalysts is considered as an evolving strategy to adjust their physiochemical properties and boost photoreactivity of the materials. Here, hydrogenation and UV light pre-treatment of TiO 2 /SiO 2 composite with the ratio of 9 : 1 (9TiO 2 /1SiO 2 ) were conducted to generate Ti 3+ and non-bridging oxygen holes center (NBOHC) defects, respectively. The 9TiO 2 /1SiO 2 composite exhibited much higher photocatalytic water splitting than neat TiO 2 and SiO 2 as a consequence of the electronic structure effects induced by the defect sites. Electron paramagnetic resonance (EPR) indicated that hydrogenated and UV light pre-treated of 9TiO 2 /1SiO 2 boosted a higher density of Ti 3+ and NBOHC defect which could serve to suppress photogenerated electron-hole pair recombination and act as shallow donors to trap photoexcited electron. Overall, both defect sites in 9TiO 2 /1SiO 2 delivered advantageous characteristic relative to neat TiO 2 and SiO 2 with the finding clearly illustrating the value of defect engineering in enhancing photocatalytic performance.