Correlation of electronic structures and crystal structures with photocatalytic properties of undoped, N-doped and I-doped TiO2

We have carried out the first-principle calculations based on density functional theory on undoped, N-doped and I-doped anatase TiO2. It was found that there are three new bands in the band gap for both doped TiO2, which is the explanation for their visible light respondency. The band potentials of I-doped TiO2 shift downwards and should have a stronger oxidation power. By analyzing the crystal structure we found the TiO6 distorted in I-doped TiO2, and this facilitated the migration of charge carriers and enhanced photoactivity. From our calculated results, we can explain their differences in photocatalytic activity under visible light irradiation.