Stability and dynamics of carbon and nitrogen dopants in anatase TiO2: A density functional theory study

The properties of carbon-and nitrogen-doped anatase TiO2, a renowned photocatalyst, depend strongly on the atomic-scale details of dopant incorporation and dynamics. Here we identify with ab initio calculations stable structures of C dopants in TiO2 that differ from previous theoretical predictions. We also describe the evolution of dopants and point defects in terms of diffusion barriers and defect complex formation. In particular, we study processes that allow dopants and oxygen native defects to migrate and initiate dopant transformations. The results reveal a range of growth and annealing conditions that can create, shift, or annihilate levels in the TiO2 band gap, altering significantly its catalytic activity.