Origin of the enhanced photocatalytic activity of (Ni, Se, and B) mono- and co-doped anatase TiO materials under visible light: a hybrid DFT study.

The characteristic properties of TiO (anatase) make doping necessary to enhance its photocatalytic activity. Herein, a density functional theory (DFT) study using the Heyd-Scuseria-Ernzerhof (HSE) hybrid functional was performed to precisely investigate the effect of mono- and co-doping (Ni, Se and B) on the structural, electronic and optical properties of anatase TiO. Notably, the origin of the enhanced photocatalytic activity of the modified systems was determined. The response to visible light was enhanced for all the mono- and co-doped materials except for B, and the highest absorption coefficient was observed for Se mono-doping and Se/B and Ni/B co-doping. The decrease in bandgap is associated with a red shift in the absorption edges with the smallest bandgap calculated for Ni/B (2.49 eV). Additionally, the Ni, Se and Se mono-doped systems and Ni/Se co-doped systems are proposed as promising photocatalysts for water splitting applications and further experimental validation. Moreover, the Ni/B and Se/B co-doped materials can also be valuable photocatalysts for other energy applications due to their enhanced visible light activity and the prolonged lifetime of their produced charge carriers.