Influence of Zr–S co-doping on the electronic structure and optical properties of anatase TiO₂: first-principles GGA + U method

Titanium dioxide has received much attraction in the field of photocatalysts applied for hydrogen production from the water splitting due to its unique set of desirable properties of non-toxicity, chemical and thermal stability, efficient photocatalytic activity and low cost. However, it is only active under ultraviolet irradiation because of the wide band gap, which limits its photocatalytic efficiency. In the present paper, the geometrical structure, dopant formation energy, electronic structure and optical properties of a series of Zr–S co-doped anatase TiO₂ were calculated by the GGA + U method based on density functional theory to narrow the band gap and expand its light absorption edge. The results show that the hybridization of O2p and S3p changes the energy levels near the top of valence band and Zr4d orbital makes a certain separation of the O2p and Ti3d orbital in conduction bands, which is helpful to prevent the recombination of electron and hole. The distance between S and Zr atom in the supercell has a significant influence on the electronic structure and optical properties of the co-doped system. The edge of co-doped TiO₂ absorption band has a certain degree of redshift. This study may provide theoretical guidance for its application in photocatalysts.