Photothermally active superhydrophobic sandwich-structured 3D COF composite for efficient crude oil remediation

Photothermal materials have attracted considerable attention for efficient solar energy conversion. A promising strategy involves leveraging the photothermal effect to reduce crude oil viscosity, thereby facilitating efficient oil–water separation. In this study, we reported the in-situ polymerization of covalent organic framework (COF) layers on cotton wool (CW). Subsequently, polydopamine (PDA) and polydimethylsiloxane (PDMS) were sequentially coated to obtain a novel sandwich-structured composite (PDMS@PDA@COF@CW). The composite exhibited excellent superhydrophobic properties with a water contact angle of 153.5°. Furthermore, it maintained an oil–water separation efficiency of 98.1 % even after 50 consecutive cycles. The material also demonstrated remarkable chemical stability under various harsh environmental conditions and possessed excellent flame retardancy. Critically, the synergistic interaction between the PDA coating and the COF framework significantly enhanced photothermal performance. Consequently, the surface temperature of PDMS@PDA@COF@CW rapidly reached 83.8 °C within 180 s under 1.0 kW/m 2 light irradiation. This study presents a highly promising solution for mitigating crude oil spills, offering valuable insights into the design of multifunctional materials for environmental remediation.