Deposition of ZnO thin films for treatment of water.

Abstract

The semiconductor heterogeneous photocatalytic technique is a kind of green technology that has been used to solve environmental pollution problems. The present study focuses on the screening of potentially photocatalytic ZnO thin films and nanostructures by using them to degrade organic dyes. Primarily Zinc chloride, nitrate and acetate salts were tested for their photocatalytic activity through the degradation of Red reactive and Methylene Blue (MB) in aqueous solution. The select compounds which are deposited by spray pyrolysis show considerable photodegradation efficiency. The studied different parameters such as concentration of dye, time deposition, salt source and seed layer position have a great effect on the photodegradation of this dye. Hydrothermal ZnO nanostructured were also tested for decolorization of MB and the results are very encourage especially for ZnO Nanorods (acetate salt) and ZnO nanoflowers for water treatment and gas sensing. Undoped and ZnO: Ag NPs films on glass and tissue, which prepared by sol-gel, show the capability of zinc oxide and silver nanoparticles to resist the growth of Gram – of K. pneumonia and E. coli by their inhibition zone which reaches 23 mm. Zinc nitrate as a precursor was used to prepare the Al/ ZnO/p-Si heterojunction by ultrasonic spray in order to investigate the photovoltaic parameters of the solar cell of this device. The I-V measurements indicate that the ideality factor n is 1.39 and the barrier height ϕb is 0.67 eV. The ϕb from I-V measurement and Norde’s function (0.69 eV) are in well agreement. While the series resistance Rs obtained from Norde’s function is found 1194 Ω. The diode has a good rectification property,photovoltaic behavior, photosensing and photoresponsivity properties. The electrical and photoelectric characterization confirms that this device is a very suitable candidate as a photodiode, photosensor applications and optoelectronic applications. The ISC and VOC were varied 11.12- 50.73 µA and 125.33- 185.22 mV for various illuminations. The C-V analysis shows that capacitance and conductance of the Al/ZnO/ p-Si diode depends on voltage and frequency. The Na, ϕb and Vbi of this structure are increased with the increasing frequencies.