Effects of oxygen vacancy on 3d transition-metal doped anatase TiO₂: First principles calculations

Highlights: • The Band gaps of doped systems were reduced by 0.51–0.96 eV compared with pure TiO₂. • Doping and oxygen vacancy are effective means to changing the hybrid strength of TMO bonding. • The band gap increases approximately linearly with the MP value of TMO bonding. In this work, systematic study of the formation energy, crystalline and electronic structures of 3d transition metal (Sc, V, Cr, Mn, Fe, Co and Ni) doped anatase TiO₂ specimens with and without oxygen vacancy has been carried out by the first principles calculations. The impurity states located at the band gaps enhance the visible light absorption, and the oxygen vacancy result in the E_F move into the CB for some doped systems, which induce the Ti³⁺ ions and promote the separation of photogenerated carriers. Doping and oxygen vacancy can change the hybrid strength and MP value of TMO bonding which has the approximately linearly with the band gap.