Investigation on the electronic structures and optical performances of Si–S codoped anatase TiO2 by first-principles calculation

• Systematic calculation on electronic and optical properties of Si/S-codoped TiO2 are performed.
• Si/S-codoped TiO2 manifests enhanced visible-light absorption as well as strong oxidizing power.
• The optical absorption of Si/S-codoped TiO2 is reinforced with increasing S doping concentration.
• Under O-rich condition, Si doping can improve the thermal stability of Si/S-codoped TiO2.
• Considering the effect of S 3p, the band gap of Si/S-codoped TiO2 may be suitable for water splitting.

The electronic and optical properties of Si and/or S (co)doped anatase TiO2 are investigated by density function theory plus U calculations. Results show that the synergistic effects of Si and S codoping result in higher visible-light absorption compared with pure and Si or S monodoped TiO2. Moreover, with increasing S doping concentration, the band gap of Si/S-codoping system becomes narrower, and simultaneously the band edge positions may be suitable for water splitting. Additionally, the defect formation energy calculations indicate that Si doping can enhance the thermal stability of TiO2 under O-rich condition.