Photocatalytic Properties of Titanium Dioxide Thin Films Doped with Noble Metals (Ag, Au, Pd, and Pt)

Sol‐gel grown TiO2 thin films are deposited on glass substrates by spin‐coating, using noble metals (M = Ag, Au, Pd, and Pt) for doping. The films are thermally treated at 500 °C, to obtain the anatase phase. The film properties are characterized by field‐emission scanning electron microscopy (FE‐SEM), energy‐dispersive X‐ray spectroscopy (EDX), X‐ray diffraction (XRD), Raman spectroscopy, profilometry, and UV/VIS/NIR spectroscopy. FE‐SEM images and EDX measurements show the presence of dopant elements in the metallic form. XRD and Raman measurements show the presence of the anatase phase for pure and doped samples. Optical measurements show the optical band gap decreases for Au and Pt doping, while it shows little change for Ag and Pd doping, compared to pure TiO2. The photocatalytic activity of all films is evaluated by measuring the rate of decolorization of methylene blue (MB) under UV irradiation. The normalization of the rate of degradation of MB according to the film thickness shows significant photocatalytic activity of all films with the following order Pt‐TiO2 > Pd‐TiO2 > Au‐TiO2 > Ag‐TiO2 > pure TiO2.