Dye degradation studies on Cu-doped TiO2 thin films developed by reactive sputtering

Abstract

TiO2 is one of the widely used photocatalysts for dye degradation and doping it with metals has shown to enhance its photocatalytic activity. In this work, Radio Frequency (RF) sputtering was used to fabricate robust, transparent Cu- doped TiO2 thin films on glass and silicon substrates at 300°C substrate temperature. Phase analysis, surface morphology and optical studies were carried out using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM) and UV–vis spectroscopy respectively. The XRD pattern of TiO2 films deposited at 300°C substrate temperature shows that they are in the pure anatase phase. The low copper doped TiO2 films showed crystalline nature; whereas with an increase in dopant concentration, the films tend to be amorphous. Moreover, the optical band gap of TiO2 was found to decrease from∼3.5 to ∼2.5 eV respectively upon Cu doping. The application potential of the Cu- doped TiO2 thin films was evaluated by monitoring the oxidative degradation of methylene blue (MB) dye under UV irradiation as a function of time. Here we could achieve the highest degradation rate of ∼32% for 1Cu/TiO2 films (intermediate doping) exposed to 90 min irradiation.