Controlled morphological and physical properties of ZnO nanostructures synthesized by domestic microwave route

Abstract

The limited applications of ZnO in the visible light are still a challenge. In a short-term reaction (15 min), controlling the growth and morphology of zinc oxide in nano-structures had been achieved using a domestic microwave as a simple, quick and inexpensive tool. Besides, no seeds substrates were needed to be immersed during preparation process. Adding capping or complexing agents helped in controlling the surface morphology of ZnO, like hexamethylenetetramine, poly(vinyl pyrrolidone) (Polyvinyl alcohol), Hydrazine hydrate, trisodium citrate and ethylenediamine. The XRD results indicated the crystalline hexagonal wurtzite phase for all ZnO samples showing crystallite size ranged from 16.8 to 31.2 nm. SEM photos for the prepared ZnO NS samples demonstrated morphologies of twin-short rod, hexagonal rod, nanowires, nanosheet, and nanoflower structures. UV–visible and PL spectroscopy for measuring the optical properties showed that the band gap of ZnO samples ranged between 3.25 and 3.21 eV and still smaller than the standard value. Sample (M2) showed the highest intensity peak at 438 nm and high broad green emission peak at 511 nm. In brief, both solvent nature and crystal growth in the specific solvents are the keys to enforcing the crystal morphology. Eventually, the antibacterial activity of zinc oxide was evaluated in the presence and absence of UV radiation. Findings showed that all aqueous solution of ZnO samples irradiated by UV exhibit more antibacterial activity due to the increased amount of H2O2 generated which is fatal to bacteria.