Photodecolorization of Rhodamine B on tungsten-doped TiO2/activated carbon under visible-light irradiation.

Tungsten-doped TiO(2)/activated carbon catalysts have been prepared by a supercritical-pretreatment-assisted sol-gel process. The structural features of the photocatalysts have been investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV/Vis diffuse-reflectance spectroscopy (DRS), electron dispersive X-ray (EDX), photoluminescence spectroscopy, and Brunauer-Emmett-Teller (BET) analysis. The results revealed that a W-TiO(2) layer was coated on the AC surface, and had higher surface area and smaller crystallite size than TiO(2)/AC obtained by a similar route. The W dopant was responsible for narrowing the band gap of TiO(2) and shifting its optical response from the ultraviolet (UV) to the visible-light region. The photocatalytic performances of the supported catalysts have been evaluated for the degradation of Rhodamine B (RhB) solution under visible-light irradiation. Compared with bulk W-TiO(2), the photoactivity was obviously enhanced when it was coated onto AC. In addition, it was found that the reactivity showed a significant relationship with the amount of W dopant, and the photoactivity order of the catalysts from weak to strong showed good agreement with their PL intensities. The effects of TiO(2) content, tungsten ion content, catalyst amount, pH, and initial RhB concentration have been examined as operational parameters. The photocatalytic reactions followed pseudo-first-order kinetics and are discussed in terms of the Langmuir-Hinshelwood model.

Li Y ，Zhou X ，Chen W ，Li L ，Zen M ，Qin S ，Sun S ... -  《-》

Electrospun nanofibers of Bi-doped TiO2 with high photocatalytic activity under visible light irradiation.

Bi-doped TiO(2) nanofibers with different Bi content were firstly prepared by an electrospinning method. The as-prepared nanofibers were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), photoluminescence spectra (PL), and UV-vis diffuse reflectance spectroscopy (DRS). The results indicated that Bi(3+) ions were successfully incorporated into TiO(2) and extended the absorption of TiO(2) into visible light region. The photocatalytic experiments showed that Bi-doped TiO(2) nanofibers exhibited higher activities than sole TiO(2) in the degradation of rhodamine B (RhB) and phenol under visible light irradiation (λ>420 nm), and 3% Bi:TiO(2) samples showed the highest photocatalytic activities.

Xu J ，Wang W ，Shang M ，Gao E ，Zhang Z ，Ren J ... -  《-》

Synthesis and visible light photocatalytic properties of polyoxometalate-thionine composite films immobilized on porous TiO2 microspheres.

Multilayer films (PW(12)-TH)(n) (PW(12)=PW(12)O(40)(3-), TH=thionine) were immobilized on porous anatase TiO(2) microspheres by layer-by-layer (LbL) self-assembly method. The porous structure of TiO(2) was confirmed by transmission electron microscopy (TEM). Scanning electron microscopy (SEM) showed that TiO(2) template particles had a round shape with an average diameter of 250 nm. The composite films were characterized by FTIR spectroscopy, UV diffuse reflectance spectroscopy and XRD spectroscopy. The results confirmed the successful immobilization of (PW(12)-TH)(n) composite films onto TiO(2) microspheres, and the growth of PW(12)-TH layer pair was uniform. SEM and TEM were also used to characterize the morphology. When PW(12)-TH composite films were assembled on the template, the surface became rougher with the increasing number of layer pair. The lattice fringe of TiO(2) became weaker when immobilized (PW(12)-TH)(n). The photocatalytic properties of the microspheres toward a rhodamine B (RhB) solution were investigated under visible light irradiation. The combination of TiO(2) and PW(12) showed an excellent photocatalytic performance. Both TH sensitization and PW(12) adsorption played important roles during the process of photocatalysis. Moreover, the catalytic property and reusability of as-prepared catalyst were relevant to the number of PW(12)-TH bilayer. The kinetics of the photodecomposition to rhodamine B followed the first-order reaction.

Yang Z ，Gao S ，Li H ，Cao R ... -  《-》

Photocatalytic activity of tungsten-doped TiO2 with hydrothermal treatment under blue light irradiation.

Tungsten doping and hydrothermal treatment were found to significantly improve the visible-light photoactivity of TiO(2) synthesized by the sol-gel method. It was observed that TiO(2) doped with a 0.5% W:Ti mole ratio and treated with 4 h of hydrothermal curing showed photoactivity under blue light irradiation equal to 74% of the commercial Degussa P-25 under UV irradiation, i.e., 0.01 mM 2-chlorophenol was completely removed in 120 and 90 min, respectively. Light absorptivity and photocatalytic activity under blue light irradiation were not dependent on the crystallite structure of the TiO(2). The oxidation kinetics under blue light irradiation can be effectively explained by the Langmuir-Hinshelwood model with an apparent reaction rate constant and a Langmuir constant of 3.60 × 10(-4) mM min(-1) and 206.53 mM(-1), respectively.

Putta T ，Lu MC ，Anotai J 《-》

Hierarchical TiO2/CdS "spindle-like" composite with high photodegradation and antibacterial capability under visible light irradiation.

Novel hierarchical TiO(2)/CdS "spindle-like" composites with uniform distribution of CdS nanocrystals on nanoporous TiO(2) mesocrystals were successfully prepared by hydrothermal and hot-injection methods. In this work, the optimal mass ratio of Ti/Cd is determined to be 2 of as-synthesized TiO(2)/CdS composites. This TiO(2)/CdS composite exhibits excellent photocatalytic activity in the degradation of Rhodamine B (RhB) and photocatalytic reaction constant is 10 times higher than that of TiO(2), 3.5 times higher than that of CdS and higher than other TiO(2)/CdS composites with different amount of Ti/Cd mass ratio. In addition, TiO(2)/CdS with optimal amount of CdS kills 99.9% of Escherichia coli in 10 min under visible-light irradiation, which shows significant higher efficiency than pure TiO(2), CdS and other TiO(2)/CdS composites. The excellent performances of this hierarchical composite are ascribed to its outstanding properties, including large specific surface area (BET), high crystallinity of oriented single-crystal-like nanoporous TiO(2) mesocrystals for charge transfer, retarded recombination of photogenerated electron-hole pairs via isolating electrons and holes in two different materials, and extended photo response of this hierarchical composite to the visible region. Considering all these superior properties and abilities, this hierarchical TiO(2)/CdS "spindle-like" composite will show great potential for applications in the water purification field.

Gao P ，Liu J ，Zhang T ，Sun DD ，Ng W ... -  《-》