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Study on the Electrochemical Preparation of Micro-nano Structures on Metal Surfaces and Their Bionic Superhydrophobic Properties

Author: LiChao
Tutor: LiZeLin
School: Hunan Normal University
Course: Physical and chemical
Keywords: Electrochemical method micron-nano structure superhydrophobicity oxide sulfide photocurrent
CLC: TB383.1
Type: Master's thesis
Year: 2011
Downloads: 254
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Abstract


Wettability is an important property of solid surfaces which is governed by the surface chemical composition and geometrical structures. Superhophobic surface, with water contact angle larger than 150°, has attracted and more interest because it is of great significance in both fundamental research and industrial applications. Conventionally, there are two methods to produce the superhydrophobic surfaces. One is to modify the surface with low energy stuff, and the other is to produce micro and nano-structures on the surface.In this paper, we report some simple and convenient electrochemical techniques on fabricating superhydrophobic surfaces. Using these techniques, we have succeeded in the preparation of superhydrophobic surface on metallic substrates of tin, copper, zinc, and bismuth.(1) Based on the electrodissolution of Sn and crystallization of SnO in the solution of NaOH, we constructed micro-nano structured SnO "pompon" films on the Sn surface under control of constant potentials. There surfaces presented superhydrophobility with a contact angle more than 150°for the water drop.(2) Using cathodic hydrogen bubbles as templates, three dimensional porous lead films were respectively electrodeposited on the substrates of copper wafers and copper grids,which were then oxidized to porous films of lead oxides by heating the deposits in the air. The porous films showed superhydrophobicity and the maximum contact angle reached to 155°. The copper grids covered with the porous lead oxide film showed both superhydrophobicity and superoileophilicity and the contact angles were 152°and less than 5°for water and kerosene, respectively.(3) Superhydrophobic porous ZnO films consisting of petal flakes or cone-shaped ZnO have been prepared by a one-step method, namely, treating the zinc electrode with square potential pulses in the solution of NaOH with or without hydrogen evolution. This surface presented superhydrophobicity without chemical modifications, and the contact angle was more than 150°.(4) Though combination of electrochemical anode oxidation and chemical conversion, we prepared urchin-like bismuth oxide and fiber-like bismuth sulfide films, respectively. The prepared surfaces have superhydrophobicity, and the sulfide film also shows good photocurrent responses.

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