Transition metal-doped one-dimensional TiO2: A synergistic experimental and DFT study for photocatalytic applications

Titanium dioxide (TiO 2 ) based photocatalysts are extensively researched; however, their limited visible-light absorption and rapid charge recombination restrict their wide practical applications. To address this issue, one-dimensional TiO 2 nanotubes doped with Fe, Co, Ni, and Cu ions were synthesized using the hydrothermal method. A key gap discussed in the current work is the integration of experimental and theoretical insights into how transition metal doping affects charge dynamics in TiO 2 . XRD confirms the anatase phase and incorporation of dopants in the lattice, while TEM reveals the tube-like morphology. Density functional theory (DFT) calculations indicate that doping reduces the HOMO–LUMO gap, thereby significantly enhancing the responsiveness to UV-Visible light. Fe, Co, Ni, and Cu-doped TiO 2 demonstrated improved photocatalytic efficiency for methylene blue (MB), methyl orange (MO), ciprofloxacin (CIP), and amaranth, with efficiencies of up to 94%, 88%, 55%, and 71%, respectively. The increased production rate of hydroxyl radicals (•OH) under illumination strongly supports the use of metal-doped TiO 2 for enhanced degradation. The current investigation facilitates an in-depth understanding of the degradation mechanism of metal-doped TiO 2 nanotubes. • Metal-doped TiO 2 nanotubes were synthesized by the hydrothermal method • XRD confirms the anatase phase, and TEM reveals the 1D-TiO 2 nanotube morphology • DFT and experiments reveal enhanced charge transfer and band gap tuning • Enhanced photocatalytic degradation of pollutants under UV-Visible light upon doping