الفهرس 
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Abstract
Today, one-dimensional zinc oxide (ZnO) nanostructures have great potential in many applications such as photocatalyst and self-cleaning. Therefore, it is really important to realize the controllable growth of ZnO nanostructures and investigate their properties. In this work, ZnO nanostructured thin films were grown onto glass substrates at different conditions by two different techniques: chemical bath deposition (CBD) and spray pyrolysis.
Firstly, a simple two-step wet chemical method was adapted to deposit nanostructured ZnO thin films. A low-cost successive ionic layer adsorption and reaction (SILAR) method was used to grow ZnO seed layers at 80 oC. Then, different hierarchical based ZnO nanostructured thin films were deposited onto the ZnO seed layers by chemical bath deposition (CBD). The influence of deposition time (tD) and pH on the surface morphology, structural, optical properties and wettability behavior of the ZnO nanostructured films were systematically investigated. The structural and morphological properties were studied by X-ray diffraction (XRD) and field emission- scanning electron microscopy (FE-SEM). The optical and wetting properties were investigated by UV-Vis spectrophotometer and water contact angle (WCA) measurement, respectively. The surface morphology revealed a complex and orientated hierarchical based ZnO nanostructured films with diverse shapes from hexagonal
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nanorods to hexagonal nanoplates and even much more complex plates/rods and flower-like shapes by changing deposition time and pH of the precursor.
XRD results confirm the synthesis of nanostructured ZnO of the hexagonal structure with a preferential orientation along (002) lattice plane. The average crystallite size, D, is altered between 41.41 to 68.43 nm dependent on the morphology of the ZnO film and pH of the precursor. At pH 6.5, the films are hydrophilic for 10 h ≤ tD ≤ 6 h and hydrophobic for 6 h < tD < 10 h. The wetting properties of the films were enhanced by increasing or decreasing pH around 6.5. Morphology and thickness of ZnO nanostructure could efficiently control transmittance, absorbance, optical band gap, and the extinction coefficient of the films. The optical band gap is blue shifted from 2.45 to 3.62 eV @ pH 6.5 as the deposition time increased from 2 to 8 h and blue shifted from 2.72 to 3.62 eV @ 8 h as the pH value increased from 5.5 to 6.5. The existence of stable hydrophobic zinc oxide nanostructured films at room temperature with large-scale and band gaps around 3.62 eV supports their use in self-cleaning and gas sensing applications. Secondly, simple spray pyrolysis set up was adapted to grow nanostructured ZnO thin films on the surface of glass substrates. In this method 0.01 M zinc acetate thermally decomposed over glass substrates at 300oC. The flow rate of the solution was changed from 20 to 100 μL/min to obtain different thickness and morphologies of ZnO films. from structural study, the prepared films at 80 and 100 μL/min showed strong (100) diffraction peak and (002) diffraction peak, respectively, which corresponding to wurtzite ZnO structure with highly orientated along c-axis. The average crystallite sizes are increased from 28.84 to 45.4 nm as the flow rate increased from 40 to 100 μL/min. The prepared ZnO films are porous in nature and pore diameter is altered between 20
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and 45 nm with an average value of 37 nm. The thickness of the deposited film is increased linearly from 80.14 to 329.8 nm with increasing the flow rate from 20 to 100 μL/min. The quantitative analysis of the ZnO is 41.69% Zn and 58.31% O, which indicates the high purity of the fabricated ZnO thin film. All samples are highly transparent (> 95 %) in the visible region and is slightly decreased with increasing the flow rate. The Eg of nanostructured ZnO films is blue shifted from 3.42 to 3.59 eV as the deposition flow rate increased from 20 to 100 μL/min. The highest Urbach energy, 397 meV, is obtained for the film that deposited at 40 μL/min. The hydrophilicity (wettability) was improved by increasing the flow rate to 80 μL/min, where the contact angle was decreased from 70 to 52.5◦. The maximum photo degradation efficiency (η) of ZnO films for the MB dye after 260 min was 93.5% and 76.9% under sunlight and 400-watt power irradiation, respectively. These results confirm the efficient use of fabricated ZnO nanostructured films in the photocatalytic degradation and self-cleaning applications.