Simple fabrication of twist-like helix N,S-codoped titania photocatalyst with visible-light response

Visible-light responsible N,S-codoped titania photocatalyst was fabricated by simple hydrolysis of titania tetrachloride using ammonia in the presence of glacial acetic acid and ammonium sulfate. The N,S-codoped titania materials were fabricated by a template-free route and demonstrated twist-like helix morphology. The morphology and microstructure characteristics of N,S-codoped titania photocatalysts were characterized by means of the N2 adsorption–desorption measurements, thermal gravimetric and differential thermal analysis (TG-DTA), transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), UV–visible diffuse reflectance spectra (DRS) and X-ray powder diffraction (XRD). The unique morphology of N,S-codoped titania materials and mesoporous microstructure were maintained after a heat treatment at 723 K for 3 h, exhibiting significantly thermal stability. The photocatalytic activity was evaluated by degrading phenol in aqueous suspension under ultraviolet and visible light irradiation. The results obtained with these novel photocatalysts are compared with the behavior of the well-studied and widely used Degussa P25 TiO2 under the same conditions. The N,S-codoped titania samples were more superior than P25 and the sample calcined under 723 K for 3 h shows the best photocatalytic activity, the higher activity of which could be attributed to its high surface area, large pore volume, well-crystallized anatase, red-shift in adsorption edge and strong absorbance of light with longer wavelength.