Effect of silver incorporation on structural and optical properties of TiO 2 thin films prepared via non-aqueous sol-gel route

Titanium dioxide (TiO2) thin films doped with varying levels of silver (Ag) (Pristine, 4 at%, 8 at%, 12 at% and 16 at%, denoted as PT, 4AT, 8AT, 12AT and 16AT) were synthesized using a non-aqueous sol-gel route and deposited using spin-coating technique. Ag doping lowered the onset temperature for anatase phase crystallization and the anatase-to-rutile transition temperature. X-ray diffraction and Raman spectroscopy confirmed a pure anatase phase in PT, 4AT, 8AT and 12AT, while the 16AT sample exhibited a mixed anatase-rutile phase. Ag was detected in both the Ag⁺ and Ag⁰ states, signifying partial doping and the presence of metallic Ag on the surface. UV-Vis spectroscopy revealed a notable reduction in the bandgap, from 3.12 eV in PT to 2.08 eV in the 12AT sample. X-ray photoelectron spectroscopy further confirmed oxygen vacancies in the 12AT sample, facilitating charge separation and suppressing recombination, as validated by photoluminescence spectroscopy. Photocatalytic activity, assessed via Rhodamine B dye degradation under sunlight, improved progressively with increased Ag content. The 12AT sample exhibited the highest photocatalytic efficiency due to its pure anatase phase, the presence of oxygen vacancies and minimized charge carrier recombination.