title: Significant enhancement of photocatalytic activity over bifunctional ZnO-TiO₂ catalysts for 4-chlorophenol degradation.
abstract: In this study, ZnO-TiO₂ binary oxide catalysts were successfully prepared by a solid-state dispersion. The catalysts were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, diffuse reflectance spectroscopy, transmission electron microscopy, Brunauer-Emmett-Teller and photoluminescence techniques. It was observed that the interaction between ZnO and TiO₂ affected the photocatalytic efficiency of binary oxide catalysts. 20 wt% ZnO-TiO₂ photocatalyst exhibited much higher photocatalytic activity than pure TiO₂, ZnO and P-25 in the degradation of 4-chlorophenol under low UV irradiation. The chemical interaction between ZnO and TiO₂ in the form of the Zn-O-Ti- bond may affect the photoefficiency of binary oxide catalysts. The profound effect of binary oxide catalyst for 4-chlorophenol degradation was generally considered due to small particle size, lower band gap energy and the presence of more surface OH groups than that of the pure TiO₂ and ZnO photocatalyst. It was concluded that in the case of 20 wt% ZnO-TiO₂ catalyst, the main intermediates of degradation were phenol, 2-chlorophenol, hydroquinone and catechol, while with P-25 the main intermediates were ring-opening products, suggesting that different reaction mechanisms may have taken place depending on the nature of the catalyst.
authors: Istanbul University, Faculty of Engineering, Chemical Engineering Department, Avcilar, 34320 Istanbul, Turkey. Electronic address: gpozan@istanbul.edu.tr.
authors: Gulin Selda
authors: GS
authors: Pozan
authors: Istanbul University, Faculty of Engineering, Chemical Engineering Department, Avcilar, 34320 Istanbul, Turkey.
authors: Ayca
authors: A
authors: Kambur
mesh_terms: D002384:Catalysis; D002733:Chlorophenols / Q000737:chemistry*; D046529:Microscopy, Electron, Transmission; D053758:Nanoparticles / Q000737:chemistry* / Q000528:radiation effects / Q000648:ultrastructure; D010316:Particle Size; D056951:Photoelectron Spectroscopy; D010782:Photolysis; D017550:Spectroscopy, Fourier Transform Infrared; D014025:Titanium / Q000737:chemistry* / Q000528:radiation effects; D014466:Ultraviolet Rays; D014874:Water Pollutants, Chemical / Q000737:chemistry*; D014961:X-Ray Diffraction; D015034:Zinc Oxide / Q000737:chemistry* / Q000528:radiation effects
chemical_list: D002733:Chlorophenols; D014874:Water Pollutants, Chemical; C009495:titanium dioxide; C029107:4-chlorophenol; D014025:Titanium; D015034:Zinc Oxide
keywords: 4-Chlorophenol; Characterization; Photocatalytic degradation; UV irradiation; ZnO–TiO(2)