Highly Stable Polyimide Composite Nanofiber Membranes with Spectrally Selective for Passive Daytime Radiative Cooling

Passive radiative cooling technology without electric consumption is an emerging sustainability technology that plays a key role in advancing sustainable development. However, most radiative cooling materials are vulnerable to outdoor contamination and thermal/UV exposure, which leads to decreased performance. Herein, we report a hierarchically structured polyimide/zinc oxide (PINF/ZnO) composite membrane that integrates sunlight reflectance of 91.4% in the main thermal effect of the solar spectrum (0.78-1.1 mu m), the mid-infrared emissivity of 90.0% (8-13 mu m), UV shielding performance, thermal resistance, and ideal hydrophobicity. The comprehensive performance enables the composite membrane to yield a temperature drop of similar to 9.3 degrees C, compared to the air temperature, under the peak solar irradiance of similar to 800 W m(-2). In addition, the temperature drop of as-obtained composite membranes after heating at 200 degrees C for 6 h in a nitrogen/air atmosphere can be well maintained at similar to 9.0 degrees C, demonstrating their ideal radiative cooling effect in a high-temperature environment. Additionally, the PINF/ZnO composite membrane shows excellent chemical durability after exposure to the outdoor environment. This work provides a new strategy to integrate chemical durability and thermal resistance with radiative cooling, presenting great potential for passive radiative cooling materials toward practical applications in harsh environments.