Bilayer CNTF/H-CNT@PDA Composite Coating with Synergistic Electrothermal–Photothermal–Superhydrophobic Functionalities for Efficient Anti-Icing and De-Icing

Developing anti-icing composite coatings integrating superhydrophobic, electrothermal, and photothermal functionalities is critical for guaranteeing the safe operation of key equipment in extremely cold environments. Layer-by-layer structural design is capable of maximizing the performance of each functional layer and avoiding overall functional failure caused by interlayer delamination. Herein, a bilayer composite coating was fabricated with a bottom carbon nanotube film (CNTF) layer and a multifunctional top coating. The underlying CNTF layer acts as an electrothermal functional layer to deliver efficient Joule heating. The top coating is composed of modified E-51 epoxy resin (M-E-51) and hexadecyltrimethoxysilane (HDTMS)-grafted polydopamine (PDA)-coated carbon nanotubes (H-CNT@PDA), which functions as a photothermally active layer, constructs a three-dimensional micro–submicrometre hierarchical superhydrophobic structure, and endows effective protection for the base CNTF layer. The prepared composite coating achieves synergistic electrothermal and photothermal de-icing performance: its surface temperature exceeds 100 °C at 3 V and reaches 52.0 °C under 0.9-sun irradiation, which is superior to the 47.4 °C achieved by pure CNTF. The coating also exhibits excellent superhydrophobicity with a water contact angle (WCA) of 156.1 ± 3.8° and a sliding angle (SA) of 6.2 ± 1.6°, along with a low ice adhesion strength of 60.1 kPa. De-icing tests verify that the coating can complete de-icing within 362 s under 1-sun illumination and 301 s under 3 V electric heating, demonstrating its outstanding dual electrothermal/photothermal de-icing capability for cold-condition anti-icing applications.