Eco-Friendly Nanoarchitectonics for Durable, Self-Cleaning, and Efficient Subambient Radiative Cooling Coatings

Passive daytime radiative cooling (PDRC) can contribute to the mitigation of global warming by dissipating heat into outer space without energy consumption. However, challenges persist in developing radiative cooling coatings with high optical performances, environmental adaptability, and multifunction synergy, limiting their practical applications. Here, an eco-friendly spray-coating approach was employed to prepare a Si₃N₄/Al₂O₃&SiO₂-PCM PDRC coating (SASPRC) based on an innovative design of spectral complementarity and synergy within atmospheric windows. The coating exhibits remarkable solar reflectance of 97.3% and infrared emissivity of 97.7%, achieving an average cooling effect of 8.2 °C below ambient temperature in direct sunlight. By incorporating phase change material (PCM), it delivers a net daily cooling power of 90.03 W m^-2, surpassing that without PCM (86.79 W m^-2). In addition to the remarkable optical characteristics and exceptional subambient cooling performance, SASPRC also demonstrates stable self-cleaning capability with a water contact angle of 165.3°, superior mechanical robustness, and excellent chemical durability. This rational design presents a viable strategy for developing high-performance radiative coolers that simultaneously address the environmental adaptability, ecological sustainability, and durability of coatings and global warming as the ultimate goal.