Porous photocatalytic activity

Li, Y., Ma, M., Wang, X., and Chen, G. (2009) Photocatalytic activity of porous titania nanocrystals prepared by nanoscale permeation process in supercritical C02 effects of supercritical conditions. Catalysis Communications,... 

Synthesis of mesoporous TiO/M composites and their photocatalytic activity in hydrogen evolution. Hydrolysis of Ti(TV) tetrabutoxide with subsequent sol-gel transformation in the presence of dibenzo-18-crown-6 ether as a template yields amorphous titanium dioxide (Fig. 1). Calcination of the parental amorphous sample at 500 °C causes crystallization of Ti02 and formation of a porous material with high specific surface area and a narrow pore size distribution with the average pore diameter 5.0 nm (Table 1, sample No. 2). Combination of the hydrothermal treatment (HTT) of Ti02 samples at 100 - 175 °C with their subsequent calcination... 

Transparent anatase Ti02-based multilayered photocatalytic films synthesized via a sol-gel process on porous alumina and glass substrates showed a sponge-like microstructure and a mean crystallite dimension of ca. 8 nm [152]. Doping such films with iron(III) impeded the photocatalytic activity. 

Zhao, Y, Zhang, X., Zhai, J., He, J., Jiang, L., Liu. Z.. Nishimoto. S.. Murakami, T., Fujishima, A., and Zhu, D. 2008. Enhanced photocatalytic activity of hierarchically micro-Znano-porous TiOj films. Applied Catalysis B Environmental 1-2, 24-29. 

Monolithic zirconia networks can also be formed using a similar procedure giving porous 2xQ>2 structures [9]. As the titania and zirconia precursors are miscible, binary inorganic networks of various Ti Zr ratios could be produced [9]. The crystallinity and photocatalytic properties of the mixed material were studied X-ray amorphous materials were produced for Ti Zr ratios of 2 8 to 7 3, and the binary material containing 10% zirconia (the presence of which inhibited crystal transformation to the rutile phase) showed the highest photocatalytic activity for the photodecomposition of sahcylic acid and 2-chlorophenol [9]. 

Cell assemblies. As macroporous templates, these provide a facile bioinspired method for the synthesis of hierarchical macro-mesoporous titania with tunable macroporous morphology and enhanced photocatalytic activity [134]. This is also a simple and facile technique that can be used to prepare many types of metal oxide porous materials with good control over the pore size and morphology. 

Furthermore, R. K. Rana et al. reported a bio-inspired assembly of Ag/ AgCl/ZnO nanostructures with poly(allylaminehydrochloride) as the mineralizer for the enhaneed visible-light-driven photocatalytic activity. The as-prepared Ag/AgCl/ZnO had a spindle- and rod-like morphology along the (OOOl)direction with a width of 100-200 nm and a length of 400-700 nm (Fig. 26A). The Ag/AgCl particles were trapped in the porous... 

Fen X, Peng Z, Alexandra N, Zheng-Yong Y, Zhen RT, Mate] H, et al. Hierarchically assembled porous ZnO nano-particles synthesis, surface energy and photocatalytic activity. Chem Mater 2007 19(23) 5680-6. 

Titania membranes show excellent chemical resistance, and can be used in both acidic and basic pH and moreover, they show interesting photocatalytic activity. Titania UF membranes have been commercialized by several companies. At present, extensive efforts have focused on the preparation of porous membranes having small pore sizes in the NF range (1-2 nm). Since pore sizes are believed to be controlled by the sizes of the packed particles, controlling the sol size is a crucial process for membrane processing. Anderson et al. [23] prepared nanosized TiOi and Zr02 particles (3-5 nm) by carrying out hydrolysis and condensation reactions of metal tcrt-amyloxide with a small amount of water (molar ratio of H20/Ti = 3—5) in tcrt-amyl alcohol solutions. Hydrolysis and condensation reactions of metal alkoxides are written as follows ... 

Gole JL, Lewis S, Lee S (2007) Nanostructures and porous silicon activity at interfaces in sensors and photocatalytic reactors. Phys Stat Sol (a) 204 1417-1422 Harper J, Sailor MJ (1996) Detection of nitric oxide and nitrogen dioxide with photoluminescent porous silicon. Anal Chem 68 3713-3717... 

Ao, Y, J. Xu, D. Fu, and C. Yuan, A simple route for the preparation of anatase titania-coated magnetic porous carbons with enhanced photocatalytic activity. 

Various Ti02 materials have been prepared by sol-gel method. For example, porous Ti02 fiber was prepared by unidirectional freezing of gel (Maki, 1985). Sakka et al. obtained a bundle ofporous Ti02 fibers ofabout 10 cm in length and 20-100 /rmin diameter, which contained small anatase crystals. They have not reported the photocatalytic activities, but in the light of applications, such morphological control will play more important role. 

H. Imai et al. have reported that the monodisperse hollow nanotubes consisting of anatase crystalline of Ti02 particles have been directly prepared in a porous alumina membrane by a deposition technique using an aqueous solution system of titania tetrafluoride. The morphology of the anatase nanotubes was highly controllable because no annealing for crystallization was required. The photocatalytic activity of the deposited anatase was... 

M.M. Yusuf et al. have reported mesoporous Ti02 films with controlled pore sizes prepared by smfactant templating sol-gel method and its photocatalytic activity. The porous films of anatase with rectangular and columnar structure were obtained by annealing after immersion of the wet gel films in benzyltrimethylammonium chloride- and cetyltrimethyl-ammonium chloride-solutions, respectively. They concluded that the microstructure of the sol-gel derived films can be controlled by changing the type of surfactant species and the concentration of surfactant solutions. The photocatalytic activity of their films for the oxidation of NO , was improved by the surfactant modification (Yusuf, 2002). 

Anpo, M., Aikawa, N., Kubokawa, Y., Che, M., Louis, C., and Giamello, E. Photoluminescence and photocatalytic activity of highly dispersed titanium oxide anchored onto porous vycor glass. J. Phys. Chem. 1985, 89, 5017. 

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