Scalable Superhydrophobic Flexible Nanofiber Film for Passive Daytime Radiative Cooling

Passive daytime radiative cooling technology can cool objects without any energy consumption. Although some progress has been made, there are still challenges in manufacturing low-cost, anticontaminant, and weathering-resistant radiative coolers for long-term cooling. Herein, a superhydrophobic flexible cooling radiator (SFCR) as a film is fabricated by a facile, inexpensive, and scalable electrospinning and electrospraying method. The SFCR film consists of poly(vinylidene fluoride-co-hexafluoropropylene) fiber frameworks adhered to by numerous microaggregates from SiO2 nanoparticles. The SFCR film exhibited a strong solar reflectivity of 98.5% and an average emissivity of more than 95%. It also showed superior superhydrophobicity and wettability with a static water contact angle of 156° and sliding angle of 2.2°. The average temperature drop of the film was 11.6 °C compared to the air around the film under sunlight. Importantly, the self-cleaning effect of the SFCR film robustly protects its surface against outdoor contamination and is conducive to sustainable cooling. This SFCR film integrating radiative cooling with self-cleaning characteristics is promising for scalable production and can be utilized on buildings, vehicles, and other terrestrial objects.