Fabrication of a self-cleaning cellulose acetate/SiO2 film for sustainable radiative cooling

Cooling materials oriented to outdoor applications should provide not only high solar light reflectivity and strong thermal emissivity but also durable resistance to rain flushing. Herein, we propose a radiative cooling porous film of cellulose acetate and SiO2 with solar reflectivity of 98.6 % and infrared emissivity of 97 %. The film achieved cooling performance with average temperature drop of 14.1 °C, showing strong cooling performance. And it is superhydrophobic with water contact angle of 166.6°, enabling it to be self-cleaned by water and stabilized to rain flushing. The self-cleaning of the film could mitigate dust pollution on the material in outdoor applications and prevent the surface from wetting in outdoor applications which sustain the radiative cooling. This work paved a way to non-wettable self-cleaning radiative cooling films using naturally evolved materials for sustainable applications.