Enhancement in the photodegradation properties of ZnO nanostructures with structural transformation

Abstract

Semiconductor based photocatalysis has been proven a benchmark in the field of environmental remediation and water detoxification. We report the synthesis of ZnO nanoflakes (ZNF) and their subsequent transformation in ZnO nanosheets (ZNS). ZNF was prepared by wet chemical method while the hydrothermal method was used for the synthesis of ZNS. The morphological variations have been confirmed through the scanning electron microscopy (SEM). The SEM results reveal the presence of nanoflakes with an average length of 187 nm. The measured average length and width of ZNS are found to be 350 nm and 120 nm respectively. Optical absorption studies reveal enhancement of absorption of ZNS as compared to ZNF. The optical band gap value of ZNF and ZNS was obtained from Tauc plot method. The estimated bandgap for ZNF and ZNS are found to be 2.7, and 3.1 eV, respectively. The crystallographic properties of ZnO samples have been studied by X-ray diffraction (XRD). ZnO samples have been employed for the decomposition of methylene blue (MB) dye under sunlight exposure. The photocatalytic studies reveal that ZNS exhibits enhanced photocatalytic activities for degradation of MB dyes solution as compared ZNF. ZNS sample decomposed the 10µM MB dye solution in just 15 min. The superior photodegradation activity of ZNS is ascribed to the high surface area and improved sunlight utilization capability.