Exploration of vanadium and rhenium co-doped TiO₂ for enhanced photocatalytic performance via first principle density functional theory investigation

Abstract

Abstract Elemental doping is an effective strategy to enhance the photocatalytic performance of TiO 2 by modifying its electronic structure through the introduction of impurity states near the valence or conduction bands. In this study, we employ density functional theory (DFT) with Hubbard U correction (DFT+U) to investigate the effects of vanadium (V) and rhenium (Re) mono-doping and co-doping on the structural, electronic, and optical properties of rutile TiO 2 . Structural optimizations reveal slight reductions in lattice constants and bond lengths in doped systems, attributed to the marginal ionic radius differences between the dopants and Ti 4+ ions. Formation energy analysis indicated that V–Re co-doping is energetically more favorable than mono-doping, suggesting high structural stability. Electronic structure analysis indicates a significant bandgap narrowing in V-doped (2.62 eV) and V–Re co-doped TiO 2 (2.75 eV), suggesting enhanced absorption in the visible region and improved photocatalytic activity. In contrast, Re mono-doping slightly increases the bandgap to 3.10 eV, limiting its activity to the UV region. Optical properties, including the dielectric function and absorption spectra, further confirm a redshift in V and V–Re doped systems, while Re doping results in a blueshift. Band edge alignment with respect to the normal hydrogen electrode (NHE) shows that all doped systems satisfy the thermodynamic criteria for water splitting, with V–Re co-doping exhibiting the most favorable band positions for hydrogen evolution. Finally, this work demonstrates that co-doping with V and Re is a promising strategy to engineer TiO 2 with improved visible-light photocatalytic performance, offering valuable insights for the design and synthesis of efficient photocatalysts for hydrogen production.

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