Efficient Visible‐Light‐Induced Photocatalytic Activity of SrTiO3 Co‐Doped With Os and N: A GGA + U Investigation

Abstract

A systematic investigation based on spin‐polarized DFT + U has been carried out to study the electronic structure of charge compensated (Os, 2N)‐codoped SrTiO3 as compared with that of pure SrTiO3, Os‐doped SrTiO3, N‐doped SrTiO3, and charge non‐compensated (Os, N)‐codoped SrTiO3. The calculated band gap of pure SrTiO3 is improved to 3.22 eV using GGA + U method by choosing appropriate U values, which is in good agreement with the experimental value (3.25 eV). Although charge non‐compensated co‐doping with (Os, N) significantly reduces the photoabsorption energy by introducing localized in‐gap impurity states of Os‐5d, N‐2p, and O‐2p, unfortunately, the presence of these states may hinder charge carrier mobility. The calculated results show that the charge compensated co‐doping with one Os and two N leads to the complete passivation of the mid gap Os‐5d and O‐2p impurity states, thus the positions of the band edges are extended to satisfy the criteria for overall water splitting under visible‐light. The present predictions demonstrate that the charge compensated (Os, 2N)‐codoped SrTiO3 can be a desirable effective photocatalyst for highly active visible‐light‐induced hydrogen production from water splitting due to the enhanced visible‐light activity as well as decreased electron–hole recombination rate.