Effect of Metal (Ni²⁺, Fe³⁺, and Mo³⁺) Doping in TiO₂ Thin Films on Antimicrobial Activity

Pure- and metal (Ni²⁺, Fe³⁺, and Mo⁵⁺)-doped TiO₂ films were prepared on soda-lime-silica glass by a spin coating-pyrolysis, to be used in antimicrobial applications. As-deposited films were prefired at 500 °C for 10 min in air, followed by annealing at 550 °C for 60 min in argon. X-ray diffraction, field emissionscanning electron microscopy, and ultra-violet-visible-near infrared spectrophotometry were used to analyze the crystal structure, surface morphology, and optical properties of the films, respectively. The largest red shift in the optical-energy band gap was obtained on the Fe³⁺-doped TiO₂ film after annealing. The number of Escherichia coli that remained after each irradiation time was counted to examine the antimicrobial ability of the films. A reduction of above 99% of Escherichia coli populations on 10 mol% Fe³⁺-doped TiO₂ films was observed after irradiation for 40 min at 375 nm.