Study On The Preparation Of Micro-nano Structured Metal Surfaces And Their Bionic Superhydrophobic Properties

In recent years, superhydrophobic surfaces with water contact angle (CA) larger than150°have attracted more and more attention due to their broad applications like self-cleaning coatings, energy conversion and conservation, separation of oils or organic solvents from water, and so on. There are two main ways to fabricate artificial superhydrophobic surfaces. One is to create a rough structure on a hydrophobic surface (CA>90°) and the other is to modify a rough surface by compounds with low surface free energy. A lot of techniques have been developed to fabricate artificial superhydrophobic surfaces. For example, templating, sol-gel process, plasma treatment, chemical etching and so on. However, most of the methods involved multisteps, harsh conditions, and/or expensive equipment and materials. Therefore, there is still a big challenge to prepare superhydrophobic metal surfaces by simple and time-saving methods.In this paper, we have successfully prepared superhydrophobic metallic surfaces of Sn/SnOx, Bi/Bi2O3, Cu, Au et al. by replacement reactions and electrodeposition.(1) Superhydrophobic Sn surfaces on zinc substrate can be facilely fabricated by a replacement reaction between Zn and acidic SnCl2solutions without any post-treatment and surface modification. The maximal CA can reach to156°.(2) Sn/SnOx (x=1and2) surfaces on different substrates have been prepared by a one-step method involving electrodeposition of3D porous dendritic metal and subsequent self-passivation of the deposited porous Sn surface. The as-prepared porous dendritic Sn/SnOx surface shows intrinsic superhydrophobicity with low water adhesion, and a maximum contact angle of165°was achieved without performing surface modification.(3) Two facile methods (displacement reaction and electrodeposition) have been employed to construct superhydrophobic Bi/Bi2O3surfaces. The hierarchical porous dendritic Bi/Bi2O3films show intrinsic superhydrophobicity and a maximum contact angle of164°without performing surface modification.(4) A series of superhydrophobic metal surfaces such as copper, nickel, cadmium, cobalt, zinc, gold, Pd and Pt have been prepared by one-step electrodeposition process. The XPS results indicate that the wettability of metallic surfaces may have been affected by the spontaneously modification of hydrocarbons from ambient air.