Vapor Exchange Induced Particles-Based Sponge for Scalable and Efficient Daytime Radiative Cooling

Abstract

Passive daytime radiative cooling technology (DRCT) has recently gained significant attention for its ability to achieve sub-ambient temperature without energy consumption, making it an attractive option for space cooling. The cooling performance can be further improved if radiative cooling materials also exhibit high thermal insulation performance. However, synthesizing radiative cooling materials that possess low thermal conductivity while maintaining mechanical durability remains a challenge. Here, a vapor exchange method is developed to prepare particles-based poly(vinylidene fluoride-co-hexafluoropropylene) sponge materials for scalable and efficient daytime radiative cooling. By tailoring the particle diameter distribution, high solar reflection (94.5%), high infrared emissivity (0.956), and low thermal conductivity (0.048 W m−1 K−1) are achieved, resulting in a sub-ambient cooling of 9.8 °C under direct solar irradiation. Additionally, the sponge material exhibits good mechanical durability, sustaining deformation with a strain up to 40%, making it adaptable to diverse scenarios. A radiative cooling material with mechanical durability and thermal insulation can thus pave the way for large-scale applications of DRCT.