Fabrication of CuZn5–ZnO–CuO micro–nano binary superhydrophobic surfaces of Cassie–Baxter and Gecko model on zinc substrates

Superhydrophobic surfaces were prepared via immersing the clean perpendicular zinc substrates into aqueous copper chloride (CuCl2) solution and followed by annealing in dry air. Two Superhydrophobic models were obtained by controlling the concentration of CuCl2 aqueous solution. One had a high water contact angle (CA) of 162 ± 2° with a small sliding angle SA of less than 2 ± 1°, which was identified with Cassie–Baxter model, the other had a high CA of larger than 150° with a high adhesion, which was identified with Gecko model. CuZn5–ZnO–CuO micro–nano binary structure leads to superhydrophobicity of the surface. Wettability and durability of surfaces were investigated and a theoretical explanation on superhydrophobic surfaces is presented. Durability test was carried out to study properties of the surface. Formation mechanism of the surface was also explained.

Graphical abstractThe zinc substrate was modified by chemical displacement at a perpendicular position and annealed to form the micro–nano binary structure with CuZn5–ZnO–CuO/zinc of Cassie–Baxter model and Gecko model, controlled by CuCl2 aqueous solution concentrations.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Micro–nano binary structure of Cassie–Baxter model and Gecko model are obtained. ► CuZn5–ZnO–CuO/zinc micro–nano binary structure leads to superhydrophobicity. ► The annealing plays an important role in superhydrophobicity of metallic materials. ► The superhydrophobic surface with Cassie–Baxter model shows a good durability.