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Hamrouni A.,Gabes University | Hamrouni A.,Schiavello Grillone Photocatalysis Group | Moussa N.,Gabes University | Di Paola A.,Schiavello Grillone Photocatalysis Group | And 4 more authors.
Journal of Photochemistry and Photobiology A: Chemistry | Year: 2015

Binary and ternary SnO2-ZnO-ZnWO4 nanocomposites were prepared by a sol-gel route. The photocatalytic activity of the samples was evaluated through the decomposition of 4-nitrophenol and partial oxidation of 4-methoxybenzyl alcohol to p-anisaldehyde. All the mixed catalysts revealed higher photoactivity than bare ZnO, SnO2 or ZnWO4 and the best performances were exhibited by the binary nanocomposites. The high photocatalytic activity was explained by the presence of heterojunctions among different semiconductors that enhance the separation of the photogenerated electron-hole pairs, hindering their recombination. As a general consideration, an essential role was played by the electronic features of the samples in the degradation reactions whereas the surface properties were key factors for the selective formation of p-anisaldehyde. © 2015 Elsevier B.V.All rights reserved.

Matos J.,Venezuelan Institute for Scientific Research | Garcia-Lopez E.,Schiavello Grillone Photocatalysis Group | Palmisano L.,Schiavello Grillone Photocatalysis Group | Garcia A.,Venezuelan Institute for Scientific Research | Marci G.,Schiavello Grillone Photocatalysis Group
Applied Catalysis B: Environmental | Year: 2010

2-Propanol was photocatalytically oxidized in the presence of binary materials composed by mixtures of home-prepared active carbon and commercial TiO2 or ZnO. Remarkable beneficial improvements of the photocatalytic activity were observed in the presence of activated carbon (AC). In particular the presence of AC along with TiO2 in the binary materials enormously increased the photocatalytic ability of the bare semiconductor to completely oxidize the substrate, indicating a synergy between the semiconductor and AC. Probably, when AC was present in the binary materials, the majority of the substrate and of the intermediates were reversibly adsorbed onto the AC surface. Due to the presence of a contact interface between TiO2 and AC, a continuous transfer of the species from the AC to the TiO2 surface was possible. On the other hand, the presence of AC avoided the deactivation of TiO2 that occurred instead for the bare semiconductor. The reaction rate in the presence of ZnO based materials was always lower with respect to that observed for the corresponding TiO2 ones, although the presence of AC improved the photoactivity of bare semiconductor in this case also. © 2010 Elsevier B.V.

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