An advanced passive radiative cooling emitter with ultrahigh sub-ambient cooling performance

Passive radiative cooling technologies are crucial for energy conservation and emission reduction, yet their development encounters substantial challenges. In this study, we fabricate an advanced passive radiative cooling emitter by coating BaSO4@SiP/H-SiO2@PAN on an aluminum substrate. This design highlights a remarkable average temperature reduction of 20.1 degrees C and an ultrahigh cooling power of 121.0 W m-2 under strong solar radiation, showcasing exceptional sub-ambient cooling performance. Through meticulous design optimization, the emitter exhibits an efficient reflectance of 95.5% in the visible spectrum and a superior mid-infrared emissivity of 97.9%. Additionally, the emitter's superhydrophobic surface, characterized by a water contact angle (WCA) of 155 degrees, ensures excellent self-cleaning properties. Furthermore, its performance remains stable even after prolonged UV exposure, demonstrating its outstanding durability. This innovative emitter provides a critical solution for energy-efficient cooling in buildings and outdoor equipment, significantly contributing to reduced energy consumption and carbon emissions. This study develops a state-of-the-art passive radiative cooling emitter with 95.5% reflectance and 97.9% emissivity, achieving an average temperature reduction of 20.1 degrees C and a cooling power of 121.0 W m-2 under intense sunlight.