UV laser-produced copper micro-mesh with superhydrophobic-oleophilic surface for oil-water separation

We report a method to fabricate micro-pore arrays on a copper sheet by a 355 nm UV nanosecond pulse laser, and investigate the effects of surface microstructures and micro-pore spacing on the wettability of the formed copper micro-mesh. We found that the surface was initially hydrophilic, but changed to superhydrophobic-oleophilic with water contact angle 151° and oil contact angle about 10° after exposed to ambient environment for 14 days. We analysed the surface morphologies of the processed samples with a three-dimensional profilometer, measured the water and oil contact angles, and characterized the surface by a field emission environmental scanning electron microscope (FESEM) and energy dispersive X-ray spectrometer (EDS). The surface chemistry changes were confirmed by X-ray photographic spectroscopy (XPS). Effective oil-water separation performance of the fabricated copper mesh was demonstrated. Learning from the natural change, we designed a coating material containing C8 long C–C (H) chain and coated onto the freshly prepared copper mesh to convert the surface property into a preferred superhydrophobic-oleophilic nature. This study provides a controllable methodology consisting laser processing and surface modification for making micro-pore copper mesh as a simple and effective method for oil-water separation.