Rapid preparation of multifunctional superhydrophobic PDA-PPy nanofiber coating for anti-icing and solar-driven steam generation

The application of photothermal superhydrophobic materials still suffer from the limit intrinsic solar absorption, the single functionality and structural instability. Herein, a durable multifunctional photothermal superhydrophobic coating was designed by the pre-self-assembly and in-situ copolymerization of pyrrole (Py) and dopamine (DA). Benefitting from the in-situ growth of Py and DA on the pre-embedded oxidant matrix (FeCl₃), the porous interwoven PPy-PDA nanofiber structure rapidly formed. After encapsulation of highly transparent polydimethylsiloxane (PDMS), the open pores and channels facilitated a remarkable 99 % light absorption by enabling multiple reflections and stable multi-scale structure. Thus, the prepared coating showed efficient photothermal conversion performance with surface equilibrium temperature 93.8 ℃ (1 kW/m²) and superhydrophobicity. In addition, the freezing time of the coating was 22.2 times that of uncoated surface passive anti-icing. Furthermore, the freezing ice could melt within 2 min and rolled off immediately under 1 kW/m² sunlight. Therefore, the prepared coating showed excellent passive anti-icing and photothermal active de-icing property. Importantly, the coating could also be used for photothermal evaporation. Under 1 sun intensity, the solar vapor evaporation rate of the coating was 2.06 kg m⁻²h⁻¹. More importantly, the coating maintained outstanding mechanical and chemical durability, which confirmed by strict tests (sandpaper abrasion test, kneading test, tape-peeling test, high temperature resistance test, strong UV radiation test and different pH solutions erosion test). The outstanding environmental adaptability has a great promise for practical applications of photothermal conversion materials.