Controlled growth of superhydrophobic films without any low-surface-energy modification by chemical displacement on zinc substrates

Superhydrophobic surface was prepared via immersing the clean perpendicular zinc substrate into aqueous copper (II) chloride (CuCl2) solution and followed by anneal under the humid condition. The prepared samples were characterized by powder X-ray diffraction analysis, X-ray photoelectron spectroscopy, energy-dispersive X-ray spectroscopy (XPS), and scanning electron microscopy (SEM), and energy-dispersive X-ray spectrometry analysis (EDX). SEM images of the films showed that the resulted surfaces exhibit micro–nano binary structures. The resulting surfaces had a high water contact angle (CA) of larger than 150° as well as a small sliding angle (SA) of less than 6°. Cu–Zn alloy formed by chemical displacement. Crystal CuZn5 formed via crystal transition via anneal treatment. Crystal ZnO formed in air or under the humid condition. The CuZn5–ZnO micro–nano binary structures leads to the surface superhydrophobicity.