Superhydrophobic-photothermal-insulating synergistic CNT/COF composite coatings for solar-powered crude oil restoration

In this study, a multifunctional composite membrane (PDMS@CNT@COF@CF) integrating superhydrophobic, efficient photo-thermal conversion, and electrical insulation properties was developed through a functional co-design strategy. The material was constructed by depositing a covalent organic framework (COF) on the surface of carbon nanotube (CNT) via room temperature in situ polymerization. It was then robustly anchored onto a cotton fabric (CF) substrate through polydimethylsiloxane (PDMS) coating. The prepared composite membrane exhibited excellent superhydrophobic in air (water contact angle of 157.4°), and achieved separation efficiencies exceeding 96.0 % for both light and heavy oils. The separation efficiency of 98.6 % with a flux of 12913.6 L/m 2 · h was maintained after 30 cycles of use. Furthermore, the in-situ modification of COF significantly enhanced the volume resistance of the material to the MΩ level, which was three orders of magnitude higher than pure CNT. Notably, under 1.0 kW/m 2 simulated sunlight, the surface temperature of the PDMS@CNT@COF@CF rase to 76.3 °C within 180 s. The synergistic photothermal-superhydrophobic effect significantly reduced the viscosity of crude oil, enabling continuous recovery when coupled with a peristaltic pumping system. It is expected to facilitate the research and development process of oil-water separation materials adapted to complex marine environments.