Development of doped ZnO thin films by successive ionic layer adsorption and reaction method for photocatalytic activities

Abstract

Nowadays residual dye pollutants are improperly disposed into the water The conventional methods like chemical precipitation coagulation and adsorption on activated carbon cannot completely remove organic dye pollutants but only transfer dyes from one phase to another causing secondary pollution and requiring further treatment Advanced oxidation processes AOPs a set of chemical treatment procedures designed to treat dyes in waste water is regarded as one of the most promising alternative methods for conventional waste water treatment methods to remove dyes from water and various industry effluents Particularly the application of metal oxide semiconductors in the advanced oxidation process has gained much attention in treating dye wastewater due to its good degradation efficiency and low toxicity and does not generate harmful secondary by product When the metal oxide semiconductor is irradiated with a suitable wavelength it generates electron hole pairs upon irradiation ZnO have strong reduction oxidation capacity non toxicity higher stability than metals and chemical inertness etc which made ZnO as effective photocatalyst in the photocatalytic process Zinc oxide has wide direct band gap of 337 eV ie in the near UV range The band gap energy and the recombination of photogenerated electrons and holes of ZnO can be modified by doping metals nonmetals or coupling semiconductors The photocatalytic property of ZnO can be enhanced by either modifying the surface morphology of ZnO thin films or by doping with the transition metals Preparation and characterization of ZnO and doped ZnO polycrystalline thin film via wet chemical techniques have attracted considerable attention due to their wide application prospects in various electronic and optoelectronic devices newline