Visible-light photocatalytic water splitting performance of V and Co codoped SrTiO₃: a first-principles study

This study employs first-principles calculations to investigate the effects of V and Co co-doping on the electronic structure, optical properties, and photocatalytic activity of SrTiO₃. The calculation results indicate that a positive defect binding energy and shortened V-O/Co-O bond lengths enhance the structural stability of the co-doped system. An intermediate band is introduced into the forbidden gap of the material via the strong hybridization between V-3d, Co-3d and O-2p orbitals, and the band gap is significantly narrowed from 3.2 eV of the pristine phase to 2.5 eV, 2.17 eV, and 1.95 eV for the near, medium, and far configurations, respectively, upon the scissors operator correction. This modification leads to a significant red-shift in the optical absorption spectrum, with the absorption edge extending from 390 nm to 650 nm and the emergence of new absorption peaks, thereby improving the light-harvesting capability in the visible region. Furthermore, band edge position analysis shows that its band edges are well-matched with the redox potentials of water, possessing the necessary conditions for water splitting. This work provides important theoretical guidance for the design of novel and efficient visible-light photocatalytic materials.