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

摘要

Sol-gel grown TiO_2 thin films are deposited on glass substrates by spincoating,using noble metals (M¼Ag, Au, Pd, and Pt) for doping. The filmsare thermally treated at 500 °C, to obtain the anatase phase. The filmproperties 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. FESEMimages and EDX measurements show the presence of dopant elementsin the metallic form. XRD and Raman measurements show the presence ofthe anatase phase for pure and doped samples. Optical measurements showthe optical band gap decreases for Au and Pt doping, while it shows littlechange for Ag and Pd doping, compared to pure TiO_2. The photocatalyticactivity of all films is evaluated by measuring the rate of decolorization ofmethylene blue (MB) under UV irradiation. The normalization of the rate ofdegradation of MB according to the film thickness shows significant photocatalyticactivity of all films with the following order Pt-TiO_2>Pd-TiO_2>Au-TiO_2>Ag-TiO_2>pure TiO_2.