Simultaneously spray-assisted assembling reversible superwetting coatings for oil–water separation

Abstract

Here, superhydrophobic cuprous oxide (Cu 2 O) with hierarchical micro/nanosized structures was synthesized via spray-assisted layer by layer assembling. The as-prepared superhydrophobic meshes with high contact angle (159.6°) and low sliding angle (1°) are covered with Cu 2 O “coral reef” -like micro/nanosized structures. Interestingly, the superhydrophobic mesh surfaces became superhydrophilic again due to the oxidization of Cu 2 O to CuO by annealing at a higher temperature (300 °C). And the superhydrophobic properties would be recovered by heating at 120 °C. Furthermore, the superwetting meshes were applied to design a miniature device to separate light or heavy oil from the water–oil mixtures with excellent separation efficiency. These superwetting surfaces by simultaneously spray-assisted layer by layer assembling technique show the potential application in universal oil–water separation. • The as-prepared superhydrophobic surface is with Cu 2 O coral reef-like micro/nanostructures. • No low surface energy materials have been involved in the method. • The spray deposition process is convenient and suitable for mass production. • The reversible wetting transition is responsive to the temperature. • The mesh can be used to separate different kinds of oils with excellent separation efficiency.