Electronic and optical properties of Cr and Cr–N doped anatase TiO2 from screened Coulomb hybrid calculations

We studied the electronic and atomic structures of anatase TiO2 codoped with Cr and N using hybrid density functional theory calculations. The nonlocal screened Hartree–Fock exchange energy is partially mixed with the traditional semilocal exchange energy. This not only patches the bandgap underestimation but also improves the description of the anion/cation-driven impurity states and the magnetization of the dopants. Cr and/or N doping modifies the valence and conduction band edges of TiO2, leading to significant bandgap reduction. Hence, Cr, N and Cr–N doped TiO2 are promising for enhanced visible light absorbance. (paper)