ZnO Nanotubes - Wet Etching

ZnO Nanotubes - Wet Etching

Material Name: ZnO
Recipe No.: 10323
Primary Chemical Element in Material: Zn
Sample Type: Nano
Uses: Etching
Etchant Name: None
Etching Method: Wet etching
Etchant (Electrolyte) Composition: Zn foils (Zn, Sigma Aldrich, 99.99%) with 0.25 mm thickness were cut into 1.0 × 1.0 cm2 samples. The foils were manually polished using silicon carbide (SiC, 3M) papers of increasing grit sizes, followed by alumina until a mirror finish was achieved. The polished samples were washed with deionized water before and after degreasing in acetone (C3H6O, RCL Labscan) for 10 min in an ultrasonic cleaner. The foils were etched in a 5% hydrochloric acid (HCl, RTC) in ethanol (C2H6O, Univar) solution for 3 min, followed by washing with de-ionized water. The samples were immersed in de-ionized water at 90°C for 4 h to produce ZnO nanorods, then washed with de-ionized water and dried to room temperature. Afterward, the as-produced ZnO nanorods were etched in potassium chloride (KCl, Merck, 99.95%) solution at 80°C to facilitate conversion into nanotubes. The effect of time and etchant concentration was studied by etching at 80°C for 1–4 h and in 0.5–3 M KCl, respectively.
Procedure (Condition): No data
Note: Zinc oxide (ZnO) hierarchical structures composed of nanorods were grown by wet oxidation of etched zinc (Zn) foils in hot water at 90°C for 4 h. The ZnO nanorods having an average topmost diameter of 490 nm were then selectively etched in 0.5–4 M potassium chloride (KCl) solution at 80°C for 1–4 h to facilitate conversion to nanotubes. Well-formed ZnO nanotubes were obtained after immersion in 1 M KCl solution at 80°C for 3 h. However, increasing the etching time to 4 h resulted in the collapse of the structure. XRD analysis showed that the nanorods and nanotubes were highly crystalline with wurtzite structure.
Reference: M D L Balela and M J A Jose, Two-Step Formation of Zno Nanotubes by Wet Oxidation and Selective Etching, International Symposium on Frontier of Applied Physics, IOP Conf. Series: Journal of Physics: Conf. Series 1191 (2019) 012061, doi:10.1088/1742-6596/1191/1/012061.