Growth of ZnO nanoflowers: effects of anodization time and substrate roughness on structural, morphological, and wetting properties

Abstract

Zinc oxide (ZnO) nanoflowers were grown on pure zinc plates through electrochemical anodization. Prior to anodization, zinc plates were artificially roughened by sanding with emery papers #1000, #1500, and #2000 grits so as to obtain varying substrate surface profiles. Thus, the effect of zinc plates’ roughness on the structural, morphological, and wetting properties was investigated by means of anodization time. X-ray diffraction measurements showed that the grown nanostructures were of wurtzite structure. Scanning electron microscope images revealed that anodization time increased the fraction of anodized surface. Additionally, increasing anodization time yields an increase in the aspect ratio of the micrometer long nanoflower spines, as well as, by increasing anodization time, from 0 to 600 s, contact angle gradually decreases for all substrate surface roughness values. The best wettability performance with the lowest contact angle with 13.46° was recorded for the sample with highest roughness (sanded with #1000) and anodized for 600 s. It is expected that the electrochemical anodization method which enables rapid and controlled formation of metal oxide nanostructures can further be a promising way to develop structures with tunable wettability.