From Waste to Superhydrophobic Marine Armor: Bionic Shark Skin Coating Achieves Recyclable Oil–Water Separation with Exceptional Stability

Efficient and durable materials are urgently required to address marine oil pollution. Herein, a robust superhydrophobic coating is fabricated on copper foam for efficient oil–water separation in harsh marine environments. A shark-skin-inspired hierarchical structure was constructed via fiber laser ablation (forming 20–50 μm microcavities) and grafted with silane-modified candle soot nanoparticles (CSNs, 100–500 nm). This design achieves a surface water contact angle of 165.5 ± 2.3° and a sliding angle below 5°. The coating demonstrates a high oil–water separation efficiency of 98.25% due to its superhydrophilicity and stable Cassie–Baxter state, along with excellent recyclability and regenerability. To ensure survivability under actual sea conditions, the coating’s durability was rigorously validated. In a 3.5 wt % NaCl solution, its anticorrosion efficiency exceeds 97%, with equally outstanding corrosion resistance in acidic and alkaline environments. After simulated long-term marine operation testing (including 2 h of high-pressure water jet, 12 h of wave loading, and 100 mechanical drop impacts), the coating maintains superhydrophobicity (contact angle of >150°). This performance stems from synergistic multiscale roughness, enhanced by dual silane coupling agents (KH550/KH570) and epoxy resin (EP) that strengthen the interface integrity between the copper substrate and composite coating through robust Si–O–Cu covalent bonds. This study proposes a scalable fluorine-free strategy for developing durable functional coatings suitable for a real-world marine oil spill emergency response.