Fabrication of ZnO Nanostructures with Self-Cleaning Functionality

Abstract

The science of biomimicry has served as a fusion point between nature and technology where one could adopt nature’s best solution for human’s use. Lotus leaf, for example, possesses self-cleaning capability due to the unique physical and chemical properties of its surface structural features. In this work, we aimed to mimic these features on glass surface using ZnO nanostructures to achieve the self-cleaning functionality. A series of ZnO films were electrochemically deposited on indium-doped tin oxide (ITO) conducting glass substrates from different aqueous electrolytes at systematically varied deposition potentials and electrolyte conditions. The surface morphology, density, orientation and aspect ratio of the ZnO micro/nanostructures obtained were characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM). ZnO ranging from two dimensional plate-like to one-dimensional needle-like micro/nanostructures were observed. Results from these studies show that lower electrolyte concentrations tend to favor one-dimensional growth of ZnO nanostructures that self-assembled into micron-size flower-like clusters at higher deposition temperatures. The ZnO-modified hierarchical dual-structured surface exhibits superhydrophobic property with water contact angle as high as 170o.

Thin Protective Coatings on Metals Formed by Organic Corrosion Inhibitors in Neutral Media

“…This mainly concerned the preparation of SHP coatings on Zn or galvanized steel with emphasis on the development of methods to create polymodal surface morphology for this purpose. Among them, a large number of works are devoted to the creation of highly developed ZnO coatings [250][251][252][253][254][255] with various micro/nanostructures and study of their protective and hydrophobic properties. Some features of the formation of protective layers on the surface of Zn and its alloys by carboxylic acids in organic solvents have already been mentioned above when considering the adsorption of succinic acid on Fe.…”

Recent Advances in Superhydrophobic Electrodeposits

“…Electrodeposition of zinc can produce surfaces with spongy, fractal and nanorod morphologies [ 63 , 64 , 65 ]. Zhang et al [ 63 ] produced zinc with a hierarchical spongy morphology by electrodeposition from ionic liquid.…”

“…Zinc oxide nanostructures were electrodeposited from an aqueous solution at varying salt concentrations and applied potentials [ 65 ]. When the concentration of electrolyte was high (5 mM ZnCl 2 and Zn(NO 3 ) 2 ), a flake-like microstructure was developed.…”