Scalable Superhydrophobic Flexible Nanofiber Film for Passive Daytime Radiative Cooling
Li-Cui Hu, Chao‐Hua Xue, Bing‐Ying Liu, Xiao-Jing Guo, Jiang-He Wang, Fuquan Deng
Abstract
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.