Photocatalyst Anatase

Abe, R., Sayama, K., Domen, K., and Arakawa, H. (2001) A new type of water splitting system composed of two different Ti02 photocatalysts (anatase, rutile) and a IOj"/r shuttle redox mediator. Chemical Physics Letters, 344 (3-4), 339-344. 

THE PHOTOCATALYSED REMOVAL OF LEAD IONS FROM SOLUTION When the photocatalyst anatase is suspended in lead(Il) acetate solution and the suspension is irradiated by a u.v. source, it is expected that the photoexcited electrons in the conduction band of the catalyst would reduce lead ions in solution, whereas the holes generated in the valence band would react at the surface forming OH radicals. These are likely to oxidise the acetate ions to CO2. 

Rapid e / h recombination, the reverse of equation 3, necessitates that D andM be pre-adsorbed prior to light excitation of the Ti02 photocatalyst. In the case of a hydrated and hydroxylated Ti02 anatase surface, hole trapping by interfacial electron transfer occurs via equation 6 to give surface-bound OH radicals (43,44). The necessity for pre-adsorbed D andM for efficient charge carrier trapping calls attention to the importance of adsorption—desorption equihbria in... 

Titania photocatalyst is used for air and water purification, photo-splitting of water to produce hydrogen, odor control and disinfectant. Crystal structure and crystallite size of titania particles are one of the most important factors that affect on the photoactivity. Photoactivity of anatase is higher than that of rutile, and increases with crystallite size [1]. Therefore, to increase photoactivity, it is desirable to find a route for the synthrais of the pure anatase titania with large crystallite size. 

Various methods are applied to the synthesis of titania particles including sol-gel method, hydrothermal method [2], citrate gel method, flame processing and spray pyrolysis [1]. To utilize titania as a photocatalyst, the formation of ultrafme anatase titania particles with large crystallite size and large surface area by various ways has been studied [4]. 

Mixed Ti-W oxides, after deposition of Pt, are active in the mineralization of toluene with sunlight excitation due to the low bandgap (2.7 eV) caused by the presence of both W and Pt in the anatase structure [87]. Vanadium was also used to prepare visible light active photocatalysts in dye degradation [88]. 

Figure 4.12 Schematic representation of the proposed reaction mechanism for overall photocatalytic water splitting using 03 - redox mediator and a mixture of Pt-Ti02-anatase and Ti02-rutile photocatalysts. Adapted from [161] (2001) with permission from Elsevier.

Baiju, K.V., Shukla, S., Biju, S., Reddy, M.L.P., and Warrier, K.G.K. (2009) Morphology-dependent dye-removal mechanism as observed for anatase-titania photocatalyst. Catalysis Letters,... 

Choi, Y., Umebayashi, T., and Yoshikawa, M. (2004) Fabrication and characterization of C-doped anatase Ti02 photocatalysts. Journal of Materials Science, 39 (5), 1837-1839. 

Kubacka, A., Colon, G., and Fernandez-Garci a, M. (2009) Cationic (V,Mo, Nb, W) doping of Ti02-anatase areal alternative for visible light-driven photocatalysts. Catalysis Today, 143 (3-4), 286-292. 

Solar light photocatalytic hydrogen production from water over Pt and Au/Ti02 (anatase/rutile) photocatalysts influence of noble metal and porogen promotion. Journal of Catalysis, 269 (1), 179—190. 

Zhang, L., He, D. and Jiang, P. (2009) Mn02-doped anatase Ti02 - an excellent photocatalyst for degradation of organic contaminants in aqueous solution. Catalysis Communications, 10,1414—1416. 

One of the main advantages of the method of EG-AC composite synthesis proposed here is a possibility of using this technique for obtaining the tri-component composites, such as EG-AC-Ti02. Composites between EG and photoactive anatase-type Ti02 are effective buoyant photocatalysts for degradation of water contaminants6,7. Their synthesis is typically a... 

Other composite photocatalysts were prepared by mounting immobilized anatase particles on mesoporous silica and silica beads [189-191], The behavior of anatase-mounted activated carbons was also studied in detail [192-194], It was even suggested that carbon-coated anatase exhibits better performance in photocatalysis than anatase itself, demonstrating high adsorptivity, inhibition of interaction with organic binders, etc. [195,196],... 

Homogeneous, nanosized, copper-loaded anatase titania was synthesized by an improved sol-gel method [197], These titania composite photocatalysts were applied to the photoreduction of carbon dioxide to evaluate their photocatalytic performance. Methanol was found to be the primary hydrocarbon product [198], Under calcination conditions, small copper particles are well dispersed on the surface of anatase titania. According to XAS and XPS analysis, the oxidation state of Cu(I) was suggested to be the active species for C02 photoreduction [199], Higher copper dispersion and smaller copper particles on the titania surface are responsible for a great improvement in the performance of C02 photoreduction. 

Various pairs of inorganic ions such as lOsVr, Fe /Fe, and Ce /Ce have been used as redox mediators to facilitate electron-hole separation in metal loaded oxide semiconductor photocatalysts [105-107], Two different photocatalysts, Pt-Ti02 (anatase) and Ti02 (rutile), suspended in an aqueous solution of Nal were employed to produce H2 and O2 under, respectively, the mediation of 1 (electron donor) and IOs (electron acceptor) [105]. The following steps are involved in a one-cell reaction in the presence of UV light. 

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