Density functional theory study of the structural, electronic and optical properties of C-doped anatase TiO2 (101) surface

• Optical properties of C-doped anatase TiO2 (101) surface were investigated.
• The incorporation of C atom can lead to the red shift of absorption edge.
• The case of C at O site performs the best ability of visible light absorption.
• The dipole moment caused by distortion has effects on the optical properties.

The effects of electronic and local structures on the optical properties of C-doped anatase TiO2 (101) surface were investigated. When C is at Ti or interstitial site, a planar CO3 unit is observed and leads to the decrease of band gap. While for C substituted at O site, although it introduces impurity states, the intrinsic band gap does not change. Furthermore, the dipole moment is calculated to explore the effect of local crystal structure on the photocatalytic ability. The results show that the dipole moment can promote the separation of charge carriers and enhance the photocatalytic activity.