How diamond-like carbon films help separate oil and water efficiently

Abstract

Oil-water separation is an important pursuit because of the ever-increasing demands both in the environment and health cares. Bioinspired superwetting materials outperforming traditional methods are promising in oil-water separation, yet now highly challenging in cost, efficiency, and robustness. Herein, for the first time, diamond-like carbon film dual-coated copper meshes were prepared via one-step electrodeposition in deep eutectic solvent based on electrode size regulation for bilateral oil-water separation. The results showed that the bilateral microstructures and wettability of the films are highly dependent on the area ratio of the cathode to the anode. Decreasing this area ratio can facilitate more charged ions in the electrolyte moving across the holes and edges to reach and deposit on the back of meshes, thus forming microstructures similar to that on the front. Especially, at the smallest area ratio of 1:16, the bilateral films exhibit nearly identical surface superhydrophobicity and superlipophilicity as well as long-term corrosion resistance and mechanical durability. The oil-water separation tests revealed that the bilateral separation efficiencies are as high as 99.8% at one time, remain above 90% even after 25 separation cycles, and can be basically restored via acetone-cleaning and air-aging. This work provides a new strategy for creating low-cost, high-efficiency, and reusable materials for bilateral oil-water separation.