Flexible Ceramic Radiative Cooling Membranes with High Reflectivity in Solar Spectrum, Excellent UV and Fire Resistance

Traditional radiative cooling technology, relying on polymers with high solar reflectivity and infrared (IR) emissivity, struggles to fulfill the requirements for building durability and fire resistance because of the polymers' inadequate ultraviolet (UV) aging resistance and flammability. To address this challenge, this work develops a fully inorganic and flexible ceramic membrane exhibiting ultra-high reflectance of 97.8% in the 0.25–2.5 µm solar spectrum and an IR thermal emissivity of 92.3% in the 8–13 µm atmospheric transparent window (ATW) band, for a maximum daytime sub-ambient temperature drop of 9.2 °C and a net radiative cooling power of 128.52 W m⁻². At the same time, the flexible ceramic membranes can endure temperatures up to 1000 °C, are non flammable, and exhibit only a 1.2% decrease in solar band reflectance after 552 h of continuous 0.7 kW m⁻² UV irradiation. The excellent UV, acid, and fire safety properties of the electrospun ceramic membrane hold promise for their long-term use in outdoor and extreme environments.