Sol–Gel and Thermally Evaporated Nanostructured Thin ZnO Films for Photocatalytic Degradation of Trichlorophenol
1 Ecole Nationale Supérieure de Chimie de Paris, Lab de Physico-Chimie de Surfaces, UMR-CNRS 7045, 11, rue Pierre et Marie Curie, 75005, Paris, France
2 Surface Protection & Corrosion Control Lab, Central Metallurgical Research & Development Institute (CMRDI), P.O. Box 87, Hellwan, Cairo, Egypt
3 Process Development Division, Egyptian Research Institute, Nasr City, PO Box 9540, Cairo, 11787, Egypt
Nanoscale Research Letters 2009, 4:627-634 doi:10.1007/s11671-009-9290-1Published: 19 March 2009
In the present work, thermal evaporation and sol–gel coating techniques were applied to fabricate nanostructured thin ZnO films. The phase structure and surface morphology of the obtained films were investigated by X-ray diffractometer (XRD) and scanning electron microscope (SEM), respectively. The topography and 2D profile of the thin ZnO films prepared by both techniques were studied by optical profiler. The results revealed that the thermally evaporated thin film has a comparatively smoother surface of hexagonal wurtzite structure with grain size 12 nm and 51 m2/g. On the other hand, sol–gel films exhibited rough surface with a strong preferred orientation of 25 nm grain size and 27 m2/g surface area. Following deposition process, the obtained films were applied for the photodegradation of 2,4,6-trichlorophenol (TCP) in water in presence of UV irradiation. The concentrations of TCP and its intermediates produced in the solution during the photodegradation were determined by high performance liquid chromatography (HPLC) at defined irradiation times. Complete decay of TCP and its intermediates was observed after 60 min when the thermal evaporated photocatalyst was applied. However, by operating sol–gel catalyst, the concentration of intermediates initially increased and then remained constant with irradiation time. Although the degradation of TCP followed first-order kinetic for both catalysts, higher photocatalytic activity was exhibited by the thermally evaporated ZnO thin film in comparison with sol–gel one.