title: ZnO/CuO hetero-hierarchical nanotrees array: hydrothermal preparation and self-cleaning properties.
abstract: ZnO/CuO heterohierarchical nanotrees array has been prepared via a simple hydrothermal approach combined with thermal oxidation method on Cu substrates. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffractometer(XRD) are employed to characterize and analyze the as-synthesized samples. The results demonstrate that the secondary growth of ZnO nanorods enclose with CuO nanowires, leading to the formation of ZnO/CuO heterohierarchical nanotrees array. The hierarchical nanostructures have isotropic crystal symmetry and they have no 6-fold (or 4-fold or 2-fold) symmetry as general epitaxial growth. Enlightened by the similarity with microstructure of lotus, the wettability of ZnO/CuO heterohierarchical nanotrees array has been investigated. It is revealed that as-prepared ZnO/CuO nanotrees array after silanization present remarkable superhydrophobic performance, which is attributed to the trapped air and hierarchical roughness. Furthermore, their wettability could be manipulated by the morphologies of hierarchical ZnO nanorods. At the optimal condition, the greatest static angle of water droplet on the obtained heterohierarchical nanotrees array could reach almost 170°, and this substrate could be used as self-cleaning surface.
authors.affiliation: Research Center for Biomimetic Functional Materials and Sensing Devices, Institute of Intelligent Machines, Chinese Academy of Sciences, Hefei 230031, PR China.
authors.forename: Zheng
authors.initials: Z
authors.lastname: Guo
authors.forename: Xing
authors.initials: X
authors.lastname: Chen
authors.forename: Jie
authors.initials: J
authors.lastname: Li
authors.forename: Jin-Huai
authors.initials: JH
authors.lastname: Liu
authors.forename: Xing-Jiu
authors.initials: XJ
authors.lastname: Huang
mesh_terms: D003300:Copper / Q000737:chemistry*; D057927:Hydrophobic and Hydrophilic Interactions; D007700:Kinetics; D036103:Nanotechnology / Q000295:instrumentation*; D053770:Nanowires / Q000737:chemistry; D010084:Oxidation-Reduction; D013499:Surface Properties; D013696:Temperature; D015034:Zinc Oxide / Q000737:chemistry*
chemical_list: D003300:Copper; D015034:Zinc Oxide; C030973:cupric oxide