A universal copper mesh with on-demand wettability fabricated by pulsed laser ablation for oil/water separation

Oil/water separation by surface wetting has become a research hotspot due to frequent oil spilling accidents and increasing industrial oily waste water. A rapid one-step approach is developed to fabricate copper mesh with high controllability in ambient air. Dynamic pulsed laser ablation directly creates microgrooves on copper mesh decorated with nanoparticles synthesized via the nucleation of laser induced plasma species and air molecules. The single device mesh separates various oil/water mixtures solely by gravity. Pre-wetting by water functionalizes the copper mesh to work in water-removing mode to permeate water and repel oil for light oil/water mixtures. On-demand wettability to oil-removing mode is demonstrated through pre-wetting by oil to permeate oil and repel water in typical heavy oil/water mixtures. Most importantly, the as-prepared copper mesh possesses high separation efficiency above 98% for a series of oil/water mixtures and superior environmental stability which can separate various corrosive materials, such as strong acidic, alkaline and salt solutions. The conditions for the existence of amphiphobicity and effects of surface topography on wettability and separation performance are analyzed in details. The as-prepared mesh can achieve scaling-up production and has potential applications for oil-spilling clean-up and industrial oily waste water treatment.