Electronic structure and optical properties of SrTiO3 codoped by W/Mo on different cationic sites with C/N from hybrid functional calculations

Abstract

The effect of C, N, Mo and W doping on the electronic structures and optical absorption in SrTiO3 system was systematically explored in this work. The optical absorption edge is substantially redshifted to the visible region due to the induced impurity states within the band gap after doping. However, the monodoping generally comes with the compensating defects, which decreases the photo-catalytic efficiency. Fortunately, the charge compensated combinations, such as ((C@O/TM@Ti), (2N@2O/TM@Ti) and (2C@2O/TM@Sr), TM = Mo, W) could overcome the shortage of monodoping case. And the band-edge alignment confirms that the water redox potentials lie between the highest occupied and lowest unoccupied states for the C@O/TM@Ti and 2N@2O/TM@Ti models, which guarantees their visible-light photocatalytic activity. Although the highest occupied states of 2C@2O/TM@Sr cases are higher than the oxygen evolution potential, the conduction band minimum still keeps strong reduction capability. Furthermore, the formation energy of defect indicates that the codoping can increase the doping concentration of C for C@O/TM@Ti cases under O-rich condition and C@O/W@Ti case under O-poor condition.