SiH/TiO2 and GeH/TiO2 heterojunctions: promising TiO2-based photocatalysts under visible light.

We use hybrid density functional calculations to find that the monolayer silicane (SiH) and the anatase TiO2(101) composite (i.e. the SiH/TiO2 heterojunction) is a promising TiO2-based photocatalyst under visible light. The band gap of the SiH/TiO2(101) heterojunction is 2.082 eV, which is an ideal material for the visible-light photoexcitation of electron-hole pairs. Furthermore, the SiH/TiO2(101) heterojunction has a favorable type-II band alignment and thus the photoexcited electron can be injected to the conduction band of anatase TiO2 from that of silicane. Finally, the proper interface charge distribution facilitates the carrier separation in the SiH/TiO2(101) interface region. The electron injection and carrier separation can prevent the recombination of electron-hole pairs. Our calculation results suggest that such electronic structure of SiH/TiO2(101) heterojunction has significant advantages over these of doped TiO2 systems for visible-light photocatalysis.