Yichun Qu

Enhanced photocatalytic activity for degrading Rhodamine B solution of commercial Degussa P25 TiO2 and its mechanisms.

In this paper, the Degussa P25 TiO(2) (P-TiO(2)) is modified by the post-treatment with the phosphorous acid, and the resulting samples are also characterized by X-ray Powder Diffraction (XRD), Raman spectra (Raman), Brunauer-Emmett-Teller (BET) surface area analyzer, Transmission Electron Microscopy (TEM), Fourier Transform Infrared Spectra (FT-IR), X-ray Photoelectron Spectroscopy (XPS), Ultraviolet-Visible Diffuse Reflectance Spectra (UV-vis DRS) and Surface Photovoltage Spectroscopy (SPS). The effects of surface-modification on the thermal stability and photocatalytic activity of the P-TiO(2) are investigated in detail. The results show that the surface-modification enhances the thermal stability of P-TiO(2), even still with a main anatase phase after thermal treatment at 900 degrees C, which is close related to the inhibition effects of the PO(4)(3-) groups on the surface mass diffusion as well as the directing connections of P-TiO(2) nanoparticles. Interestingly, the modified P-TiO(2) by thermal treatment at 700 and 800 degrees C can exhibit much higher photocatalytic activity than un-modified ones. The reasons for the activity enhancement are involved with the enhanced anatase thermal stability, consequently improving photoinduced charge separation rate, and still keeping large surface area and a certain amount of surface hydroxyl groups.

Enhanced activity of bismuth-compounded TiO2 nanoparticles for photocatalytically degrading rhodamine B solution

TiO(2) nanoparticles compounded with different amounts of bismuth were prepared by a sol-gel method, and the effects of compounding bismuth on the phase transformation, photoinduced charge separation and photocatalytic activity for degrading rhodamine B solution were mainly investigated, along with enhancement mechanism of photocatalytic activity of TiO(2) nanoparticles by compounding bismuth species. It can be confirmed that, by means of X-ray diffraction (XRD), surface photovoltage spectroscopy (SPS) and ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS), compounding bismuth can extend the optical response, and effectively inhibit the phase transformation process from anatase to rutile, consequently greatly improving the anatase crystallinity so as to promote the photoinduced charge separation. These factors are responsible for the increase in the photocatalytic activity of TiO(2) compounded with an appropriate amount of bismuth species.

Facile fabrication of efficient AgBr-TiO2 nanoheterostructured photocatalyst for degrading pollutants and its photogenerated charge transfer mechanism.

A simple microemulsion-like chemical precipitation method has been successfully developed to construct effectively-contacted AgBr-TiO(2) composite. The key of this method is the dual roles of Br(-) in the synthetic process, as linkers between cetyltrimethyl ammonium cation surfactants and nanocrystalline anatase TiO(2) in the acidic condition, and as bromine sources to directly produce nanocrystalline AgBr on the surfaces of TiO(2) by chemical precipitation. It is well demonstrated that the as-constructed AgBr-TiO(2) nanoheterostructured composites display effective photogenerated charge transfer between AgBr and TiO(2), favorable to improve charge separation, by means of the surface photovoltage technique in different atmospheres at the aid of outer electric fields, especially for the transient surface photovoltage technique in air. And also, the Br(-) in crystal lattice of AgBr could effectively capture photogenerated holes under illumination. These factors are well responsible for the enhanced activity for photocatalytic degradation of liquid phase aqueous phenol solution and gas phase acetaldehyde under either UV-visible or visible irradiation, and the stability of AgBr in the photocatalytic processes.