Abstract
Abstract
Lutetium-doped titanium dioxide (TiO₂) nanoparticles with a dopant concentration of 5 mol% were synthesized via a controlled sol–gel route to elucidate the influence of rare-earth incorporation on the structural, optical, electrochemical, gas-sensing, and photocatalytic properties. Powder X-ray diffraction confirmed the retention of the anatase TiO₂ phase after Lu incorporation, accompanied by slight lattice distortion and no secondary phase formation. X-ray photoelectron spectroscopy verified the presence of trivalent Lu
3
⁺ ions and defect-associated oxygen vacancies, while the Ti oxidation state remained unchanged. Elemental composition and effective dopant incorporation were further corroborated by energy-dispersive X-ray spectroscopy and atomic absorption analysis. Morphological studies revealed nanocrystalline particles with an interconnected architecture, facilitating efficient charge transport. Compared to undoped TiO₂, Lu-doped TiO₂ exhibited enhanced optical absorption with a reduced band gap, improved electrochemical stability as evidenced by cyclic voltammetry, chronoamperometry, and electrochemical impedance spectroscopy, and a stable photoelectrochemical response under applied bias. The material also demonstrated high selectivity, repeatability, and reliable response–recovery behavior toward ammonia gas sensing. Photocatalytic degradation studies showed efficient pollutant removal with good recyclability, following pseudo-first-order reaction kinetics. The synergistic effects of Lu-induced defect states and nanostructured morphology render 5 mol% Lu-doped TiO₂ a promising SDG multifunctional material for energy conversion, gas sensing, and environmental remediation applications.