Self-Cleaning and Anticorrosive Silica Microsphere@Boron Nitride Nanosheets Core-Shell Hierarchical Structure for...

Passive radiative cooling is a promising technology that can achieve high-efficient cooling by reflecting solar radiation while simultaneously emitting heat without consuming energy. However, to precisely construct the microstructure of the materials is crucial to maximize their performance. Herein, a self-cleaning and anticorrosive 3D silica microsphere@boron nitride nanosheets core-shell hierarchical structure (SiO₂@BNNSs) stacked coating is fabricated on the surface of aluminum oxide substrate. The cooperative integration of prominently sunlight reflective BNNSs and highly selective infrared emissive SiO₂ microspheres, combined with sunlight scattering brought by the 3D interconnecting configuration, results in an outstanding solar radiation reflectance of 0.84 and a mid-infrared emittance of 0.82 for the SiO₂@BNNS coating. These features enable the SiO₂@BNNS coating to exhibit excellent passive radiative cooling performances with high temperature drop of ≈17.5 °C on sunny day and ≈8.1 °C on overcast day, respectively. More importantly, the SiO₂@BNNS coating also exhibits self-cleaning performance and corrosion resistance in both acidic and alkaline conditions, ensuring the preeminent stability over a long time for various practical applications. This work demonstrates that the hybridization of the high reflection, scattering, and emittance of different materials through reasonable structure design can achieve high-efficient passive radiative cooling, offering promising prospect for energy-saving cooling technology.