TiO2 hollow microspheres impregnated with biogenic gold nanoparticles for the efficient visible light-induced photodegradation of phenol

Abstract In this study, titania hollow microspheres were prepared via sol–gel process followed by autoclaving at 180 °C for 20 h using titanium (IV) oxysulfate and ammonium fluoride. Different amounts of Au in a water-dispersible sol obtained from carambola fruit extract at room temperature were incorporated into the synthesized TiO 2 to prepare Au/TiO 2 nanocomposite. The physicochemical properties of the synthesized products were studied by X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, N 2 adsorption–desorption analysis, ultraviolet-diffuse reflectance spectroscopy, photoluminescence spectroscopy, field emission scanning electron microscopy, and transmission electron microscopy. The prepared Au/TiO 2 nanocomposite was applied to study the photocatalytic degradation of phenol (a toxic organic pollutant) under irradiation by visible light. The Au/TiO 2 nanocomposite containing 5 wt% Au had the smallest band gap energy of 2.24 eV and the maximum photocatalytic efficiency (95%), where it decomposed 97.5% of the organic pollutant after irradiation by visible light for 1 h.