Structural and Optical Properties of ZnO Nanostructures Synthesized by Hydrothermal Method at Different Conditions

Abstract

ZnO nanostructures were synthesized by hydrothermal method at different temperatures and growth times. The effect of increasing the temperature on structural and optical properties of ZnO were analyzed and discussed. The prepared ZnO nanostructures were characterized by X-ray diffraction (XRD), UV–Vis. absorption spectroscopy (UV–Vis.), Photoluminescence (PL), and scanning electron microscopy (SEM). In this work, hexagonal crystal structure prepared ZnO nanostructures was observed using X-ray diffraction (XRD) and the average crystallite size equal 14.7 and 23.8 nm for samples synthesized at growth time 7 and 8 hours respectively. A nanotubes-shaped surface morphology was found using scanning electron microscopy (SEM). The optical properties showed that the samples had good absorbance in the UV-Vis. region and wide band gap. The PL spectrum displayed that the intensity of ultraviolet (UV), band gap and defect bands depend on the growth temperature of the ZnO nanostructure. The largest band gap was 3.351 eV for ZnO nanostructure synthesized at 100 °C and growth time 8h.

On the properties of ZnO nanorods (ZnO NRs)/NiO heterostructure prepared by double chemical bath deposition

“…These findings are in good agreement with XRD data. Similar findings have been reported by other researchers [28,37,38]. Looking at these properties, it is evident that these materials are potential candidates for use as the ultraviolet detectors and photocatalysis applications.…”

“…The obtained values of bandgaps are relatively smaller compared to the reported value of bulk ZnO. This could be due to the band-bending effect attributed to the smaller size of the crystallite [37]. These findings are in good agreement with XRD data.…”

Preparation of CuO loaded cation exchange resin composites and its degradation of polyacrylamide aqueous solution

“…This may be because the hydrothermal environment at 80°C speeds up the migration of metal ions, and promots some adsorbed Cu 2+ to detach from the resin surface and pores, which causes that the content of Cu in the final product is less than that in the product without hydrothermal process. 30 Additionally, the polyethylene glycol-400 dispersant has a certain viscosity, which is conducive to the dispersion and uniform slow release of Cu 2+ , 31 so as to approach the resin particles and enter the interior of the resin orderly, resulting in an increase in the content of Cu on the surface and cross section of the resin. 32 However, considering the SEM results of the resin surface and cross section, the micro morphology of “CuO@CER-Lack of hydrothermal” and “CuO@CER-Hydrothermal/dispersant” is irregular and not ideal, which may have adverse effects on the subsequent photocatalytic applications.…”