Wetting Transition from Hydrophilic to Superhydrophobic over Dendrite Copper Leaves Grown on Steel Meshes

Abstract

With the development of water purification technologies, the usage of superhydrophobic meshes is increased but the fabrication of durable and cost effective superhydrophobic meshes is still challenging. Here, the formation of hierarchical copper fractals on stainless steel meshes and their superhydrophobicity without any physical or chemical modification were studied. In addition, the improvement of superhydrophobicity of surfaces during storing in a glass bottle for a long time (> one year) is reported. The structures were prepared using electrodeposition method applying cyclic voltammetry and square pulse deposition approaches on stainless steel meshes with 50 µm, 100 µm and 200 µm pore sizes. The prepared layers are a composition of copper with varying amounts of cuprite (Cu2O) depending on deposition method and mesh pore size. As-prepared cyclic voltammetry layer on 100 µm mesh showed the parahydrophobicity with the contact angle of 154° but a large sliding angle. The one-year stored samples in the glass bottle showed superhydrophobicity with the contact angles larger than 150° and sliding angles in the range of 4°–20°. The observed improvement of superhydrophobicity is a great success in the realm of industrial water purification, while most other proposed samples by the others have problems related to the durability of superhydrophobicity.