Synthesis and characterization of C-N-S-tridoped TiO2 nano-crystalline photocatalyst and its photocatalytic activity for degradation of rhodamine B

C-N-S-tridoped TiO2 nano-photocatalysts were synthesized through simple one-step sol-gel reactions in the presence of biomolecule cystine. The resulting materials were characterized by X-ray diffraction (XRD), N-2 physical adsorption, X-ray photoelectron spectroscopy (XPS), Fourier transition infrared spectra (FT-IR), and ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS). XRD results showed that tridoping with C, N and S could effectively restrain the phase transformation of TiO2 from anatase to rutile and growth of the crystallite sizes. DRS results revealed the light absorption of C-N-S-tridoped TiO2 was red-shifted to visible region. XPS and FT-IR analysis demonstrated that S was incorporated into the lattice of TiO2 through substituting titanium atoms, N might coexist in the forms of N-O-Ti and O-Ti-N in tridoped TiO2, and C could form a mixed layer of carbonate on the surface of TiO2. Further, the activities of the as-synthesized catalysts were evaluated for the photodegradation of rhodamine B (RhB) in aqueous suspension under visible and UV light irradiation. It was found that C-N-S-tridoped TiO2 presented higher photocatalytic activity than that of pure TiO2 and P25 TiO2. The excellent photocatalytic activity of C-N-S-tridoped TiO2 could be attributed to the small crystal size, high surface area, large surface hydroxyl groups, strong light absorption in visible region and narrow band gap. (C) 2013 Elsevier Ltd. All rights reserved.