Origin of the enhanced photocatalytic activity of (Ni, Se, and B) mono- and co-doped anatase TiO2 materials under visible light: a hybrid DFT study

Abstract

The characteristic properties of TiO₂ (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 TiO₂. 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_int, and the highest absorption coefficient was observed for Se⁴⁺ mono-doping and Se/B_int+sub and Ni/B_sub co-doping. The decrease in bandgap is associated with a red shift in the absorption edges with the smallest bandgap calculated for Ni/B_sub (2.49 eV). Additionally, the Ni, Se⁴⁺ and Se²⁻ mono-doped systems and Ni/Se⁴⁺ co-doped systems are proposed as promising photocatalysts for water splitting applications and further experimental validation. Moreover, the Ni/B_int+sub and Se/B_int+sub 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.