Investigation of the pH effect in hydrothermal growth of zinc oxide nanostructures

• Main Authors: Zulkifli, Nor Ashikin, Hasbullah, Nurul Eddahanie, Ameruddin, Amira Saryati, Awang, Noor Azura, Ahmad, Mohd. Khairul
• Format: Article
• Language: English
• Published: 2020
• Subjects: TP155-156 Chemical engineering
• Online Access: http://eprints.uthm.edu.my/1017/1/J11903_bf8b848c39b100e6fb59572685eaa8f9.pdf; http://eprints.uthm.edu.my/1017/; https://doi.org/10.5373/JARDCS/V12SP2/SP20201135
• Institution: Universiti Tun Hussein Onn Malaysia

This study focuses on the influence of the pH value of hydrothermal solution on the morphology and the transmission spectrum of zinc oxide (ZnO) nanostructures using field-emission scanning electron microscope (FE-SEM) and ultraviolet-visible (UV-Vis) spectroscopy, respectively. The ZnO nanostructures were grown on glass substrates at 90oC for 5 hours. The pH and the concentration of the starting solutions were varied from 2.03 to 12.02 and 6 mM to 100 mM respectively. Various ZnO structures of neuron-like, flowerlike, and urchin-like morphologies were obtained at alkaline pH (~8.00 to ~9.00) while for pH solution lower than ~8.00, rod-like nanostructures were obtained. Solution of pH value <4.6 and >11.50 shows that growth of nanostructures was suppressed due to the high susceptibility to erosion in both acidic and alkaline solutions. By changing the concentrations of the solution, the density and size were also varied. The increase in concentration lead to the increase of nanostructure density and the diameter of ZnO nanorods. The trend shows that the concentration solution from lower (C < 6mM) to a higher concentration (C > 100mM) resulted ZnO nanostructures such as nanorods to thick film due to overgrowth and coalescence of the nanostructures with more available precursors.