Reversible Wettability of a Chemical Vapor Deposition Prepared ZnO Film between Superhydrophobicity and Superhydrophilicity

Abstract

A superhydrophobic ZnO thin film was fabricated by the Au-catalyzed chemical vapor deposition method. The surface of the film exhibits hierarchical structure with nanostructures on sub-microstructures. The water contact angle (CA) was 164.3°, turning into a superhydrophilic one (CA < 5°) after UV illumination, which can be recovered through being placed in the dark or being heated. The film was attached tightly to the substrate, showing good stability and durability. The surface structures were characterized by scanning electron microscopy and atomic force microscopy.

The tunable wettability in multistimuli-responsive smart graphene surfaces

“…Notably, the switchable wettability of the graphene film originates from the adsorption-desorption process of oxygen molecules on the graphene surface, following that of transition metal oxides and CNTs. [16][17][18][19][20][21] Moreover, the experimental results also indicated that the transition was strongly dependent on the level of light irradiation energy and the special chemical composition of the graphene surface. The diversity of wettability on the graphene surface was closely related to the stability of absorbed solvent molecules during ultrasonication.…”

One-Step Deposition Process to Obtain Nanostructured Superhydrophobic Thin Films by Galvanic Exchange Reactions

“…Top-down approaches encompass lithographic and template-based techniques [10], laser ablation technique [11] and plasma treatment of the surfaces [12,13]. Bottom-up approaches mostly involve self-assembly and self-organization [14], such as chemical bath deposition (CBD) [15,16], chemical vapor deposition (CVD) [17] and electrochemical deposition [18]. Such surfaces are usually coated with a low surface energy material as a second step to eliminate or reduce further interactions with water.…”

Fabrication of Novel Superhydrophobic Surfaces and Water Droplet Bouncing Behavior — Part 1: Stable ZnO–PDMS Superhydrophobic Surface with Low Hysteresis Constructed Using ZnO Nanoparticles

“…The CA on these surfaces increased from 110 • to 156 • with decreasing concentration of zinc ion precursor, demonstrating controllable wetting behavior. Liu et al [19] fabricated ZnO films by Au-catalyzed chemical vapor deposition (CVD) method. The surface of as-synthesized film exhibited hierarchical structure with sub-microstructures with CA about 164.3 • , and UV illumination could switch the surface from hydrophobic to hydrophilic.…”

“…The hydrothermal method and electrochemical deposition are relatively complex and difficult to apply for mass production. As for the CVD method [19] mentioned above, a catalyst is needed for the growth of ZnO film which means the catalyst layer should be deposited on the substrate in advance. As for direct oxidation method, a Zn seed layer is needed to produce a superhydrophobic surface.…”