Synergistic CuO/CNT Photothermal Coating on Polyurethane Sponge for Rapid Viscous Crude Oil Adsorption and Recovery

The efficient remediation of viscous crude oil spills remains a significant challenge due to its limited flowability under ambient conditions. This study reports a multifunctional sponge fabricated by coating a polyurethane (PU) framework with a ball-milled PU/CuO/CNT ink, followed by polydimethylsiloxane encapsulation. The resulting sponges exhibit exceptional mechanical robustness, sustaining 60% compressive strain and maintaining 98% height retention after 5,000 cycles, coupled with high hydrophobicity (water contact angle ≈ 145°). Synergistic light absorption by CuO and CNT enables a broadband efficiency of 97.76%, achieving rapid surface heating to 85.7 °C within 2 min under 1 sun illumination. The photothermal effect reduces oil viscosity, accelerating adsorption rates by 60-fold and achieving high uptake capacities (25.8–66.6 g g –1 ). The sponge maintains stable performance under harsh environments, including exposure to strong acids, alkalis, seawater, and UV radiation. When coupled with a solar-driven, peristaltic pump-assisted recovery system, the sponge enables efficient removal of floating oil from water within 6 min. These results highlight the potential of this multifunctional sponge as a practical and sustainable material for marine oil spill management.