Facile Two-Step Strategy for the Construction of a Mechanically Stable Three-Dimensional Superhydrophobic Structure for Continuous Oil–Water Separation

It has been a big challenge to separate oil slicks from oil-polluted water sources efficiently and in an environmentally friendly way. Three-dimensional (3D) hydrophobic and superoleophilic materials have great potential in water separation continually. In this study, we developed a facile two-step strategy for fixing functionalized nanoparticles on 3D complex macroscopic surfaces. By using commercial glue to immobilize different types of nanoparticles on the surfaces of various 3D objects, superhydrophobic copper foam, cotton wool, and polyurethane (PU) sponge with strong stability and excellent performance were prepared. Owing to flexible fixing with the glue, the prepared PU sponge remained superhydrophobic after 950 mechanical compression cycles, 250 cycles of absorption/squeezing, or soaking in n-dodecane for 60 h. The prepared PU sponge was applied to the rapid absorption of clean oil on a water surface, and the feasibility of separating mixed oil through capillary separation of cavernous bodies was examined. Furthermore, the method for loading nanoparticles onto a 3D structure can be used with many self-cleaning, flexible electrodes and catalysts.