Preparation of a Super‐Hydrophobic Zinc Coating with a Hierarchical Structure Inherited from the Indicalamus Leaf through Electroplating

Abstract

treatment to create a low surface energy. [9][10][11][12][13][14] However, these biomimetic structures still vary considerably from those found in nature. To some extent, this limits the further development of super-hydrophobic materials. Nevertheless, morph-genetic materials present a novel preparation method for materials using biological structures as templates and modifying their chemical compositions to obtain new materials with structural similarities to the original biological substrate. Thus, natural templates can impart their properties onto the synthetic materials. Researchers have begun to use this method to develop super-hydrophobic materials, such as Cu, ZnO, and Si biomorphic materials, which were prepared using lotus leaves or wood as templates. [15][16][17] Zinc is an industrially important nonferrous metal, with excellent properties such as ductility, wear resistance, and casting. In particular, zinc and its alloys display excellent resistance to corrosion because a layer of dense oxide film forms on their surfaces. Therefore, zinc is often galvanized onto other materials as an anticorrosion coating, and is widely used in the automobile, shipbuilding, construction, and other light industries. However, zinc coatings adhere to acidic solutions and are easily corroded in humid and acidic environments. They are also easily stained by water under damp working conditions, which can negatively impact the appearance of the products. A variety of environments can result in corrosion to some extent, but water often plays an essential role, necessitating the fabrication of super-hydrophobic zinc surfaces. This technology will advance the field toward the goal of achieving super-hydrophobic zinc coatings, which prevent moisture absorption and corrosion and address the issues presented above.The indicalamus leaf is naturally super-hydrophobic due to its hierarchical surface structure, which is shown in Figure 1. Water droplets formed spheres with a contact angle of 151° on the surface of the leaf, as shown in Figure 1a. We found that its microstructure consists of many linear arrangements of micrometer-scale mastoids in 1D grooves on the leaf surface, as shown in Figure 1b. The diameters of these mastoids are 3-6 µm, as shown in Figure 1c. Moreover, there are numerous nanoscale flower-like slices on each mastoid, as can be seen in Figure 1d, with thicknesses of 70-100 nm. This hierarchical structure imparts hydrophobicity to the indicalamus leaf. Inspired by the concept of morph-genetic materials, we have Inspired by the idea of deriving morph-genetic materials from natural templates, the indicalamus leaf is used as a template in an electroplating method designed to prepare a zinc surface with a hierarchical microstructure similar to that of the indicalamus leaf. The leaf templates are first sintered at high temperature under vacuum to leave the carbon skeleton of indicalamus leaf behind; a layer of zinc is then plated directly onto this surface. The zinc coating inherits both the nanoscale slice structures a...