Facile wet chemical synthesis of ZnO nanosheets: Effects of counter ions on the morphological, structural, optical and photocatalytic properties

Abstract

A facile low temperature wet chemical synthesis of ZnO nanosheets with tunable thickness is reported. Well defined ZnO nanosheets were obtained by simply varying the zinc precursor (zinc acetate, zinc sulphate and zinc nitrate). The effects of counter ions on the morphological, optical, structural and photocatalytic behavior of the synthesized ZnO nanosheets were investigated. Atomic force microscopy studies revealed appreciable changes in the morphology and significant decrease in the thickness (from 23 nm to 9.5 nm) of ZnO nanosheets as the counter ions were changed from acetate to sulphate ions. Photoluminescence spectroscopy and optical absorption studies showed that the counter ions appreciably affect the optical properties of the prepared nanosheets. The intensity of UV emissions from ZnO nanosheets followed the order of counter ions: acetate < sulphate < nitrate. Photocatalytic removal of methylene blue by the prepared ZnO nanosheets was also studied. The photocatalytic activity of ZnO nanosheets followed the order of counter ions: acetate > sulphate > nitrate. The origins of the observed subtle changes in the thickness and the variations in the optical, morphological and photocatalytic behavior of ZnO nanosheets with variation in the counter ions are tentatively proposed.