Enhanced Photocatalytic Activity of Rare Earth Metal ( Nd and Gd ) doped ZnO Nanostructures

Presence of harmful organic pollutants in wastewater effluents causes serious environmental problems and therefore purification of this contaminated water by a cost effective treatment method is one of the most important issue which is in urgent need of scientific research. One such promising treatment technique uses semiconductor photocatalyst for the reduction of recalcitrant pollutants in water. In the present work, rare earth metals (Nd and Gd) doped ZnO nanostructured photocatalyst have been synthesized by wet chemical method. The prepared samples were characterized by X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM) and energy dispersive X-ray spectroscopy (EDS). The XRD results showed that the prepared samples were well crystalline with hexagonal Wurtzite structure. The results of EDS revealed that rare earth elements were doped into ZnO structure. The effect of rare earth dopant on morphology and photocatalytic degradation properties of the prepared samples were studied and discussed. The results revealed that the rare earth metal doped ZnO samples showed enhanced visible light photocatalytic activity for the degradation of methylene blue dye than pure nano ZnO photocatalyst. Introduction. The photocatalytic degradation of organic pollutants such as dyes or pesticides from water using semiconductor materials has recently attracted a lot of attention. Among photocatalysts, Zinc oxide (ZnO) have received much attention owing to its stable structure, wide direct bandgap, nontoxicity, high photocatalytic activity, mild reaction conditions and reasonable cost[1]. However, in practical applications, the photocatalytic activity of ZnO is greatly limited by its wide band-gap (3.37 eV) which makes it poor response towards visible light and rapid recombination rate of photogenerated electron-hole pairs which inhibits its photocatalytic reaction. Hence, various strategies have been adopted to enhance the photocatalytic activity of ZnO. It is well known that doping is an effective method to improve the photocatalytic activities. Recent studies revels that the rare earth (RE) ions doping on ZnO can introduce impurity energy levels in band gap and expanded its visible light response [2-6]. Furthermore RE ions doping can produce traps for photogenerated charge carriers and decreased the electron–hole pairs recombination rate. Several methods have been adopted to synthesize pure and RE doped ZnO structures, including microwave heating process, hydrothermal method, chemical co precipitation method, chemical vapour synthesis and sol-gel method. In this paper a template free precipitation method was used to prepare RE doped ZnO nanopowders. This method is simple, inexpensive and high yield providing room temperature synthesis of pure and doped ZnO nano powder. Experimental Details. Pure and RE (Nd and Gd) doped ZnO nano powder were synthesized using wet chemical precipitation method. Initially, 0.25M of ZnCl2 and 2mol% of each doping rare earth 23© 2017 The Authors. Published by Magnolithe GmbH. This is an open access article under the CC BY-NC-ND license http://creativecommons.org/licenses/by-nc-nd/4.0/