Sol-gel synthesised silver doped TiO2 nanoparticles supported on NaX zeolite for photocatalytic applications

Silver doped TiO2 nanocomposite [1% (w/w)] and undoped nano-TiO2 particles were prepared by sol-gel method from tetraporopyl orthotitanate as the precursor. To improve the photocatalytic efficiency, silver doped TiO2 nanoparticles were immobilised on NaX zeolite and used as photocatalyst. Chemical composition and optical absorption of the photocatalyst were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), infrared and ultraviolet-visible absorption spectroscopy. The XRD patterns show that the supported TiO2 are crystallised in anatase phase, and the intensity of the zeolite peaks decreases with the increase in TiO2 loading. Characterisation of samples by SEM indicates that the outer surface of the zeolite crystals is covered by the titania particles. Infrared spectroscopy revealed that the nanosize titanium oxide particles are linked to the framework through Ti-O-Si bonds. Ultraviolet-visible diffuse reflectance spectrum of metal doped TiO2 nanocomposite shows red shift in the band gap transition. The photocatalytic performances of these composite semiconductors were examined with respect to an azo dye, Orange G. The effects of pH and irradiation time on photodegradation were investigated. According to the UV-vis absorption spectroscopy results, the photodegradation of orange G dye under UV light irradiation in the presence of silver doped TiO2/NaX zeolite catalyst is more efficient than the Ag/TiO2 nanocomposite and also undoped nanotitanium oxide powder.