High-Performance Radiative Cooling Using a SiO₂/PHBV Fiber Membrane with a Micronano-Multistage Structure

Radiative cooling has emerged as a highly innovative, clean, and environmentally sustainable cooling solution, leveraging passive heat dissipation without the need for additional energy inputs. Herein, we introduce an advanced radiative cooling fiber membrane incorporating 10 wt % SiO₂/PHBV with a micronano-multistage architecture. This membrane is fabricated via electrospinning technology, utilizing poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) as the biodegradable matrix, which features multiple absorption peaks within the atmospheric window. The SiO₂ nanoparticles embedded within the membrane enhance Mie scattering and act as selective emissive materials in this window. The fiber membrane achieves an impressive solar reflectivity of 0.95 and an emissivity of 0.89 in the atmospheric window. When exposed to direct sunlight with an average radiation intensity of 537.06 W/m², the membrane's cooling temperature is 4.85 °C, yielding a temperature differential of approximately 12.8 °C relative to human skin. The average cooling power of the membrane is 64.05 W/m², with a peak cooling power of 91.75 W/m² under an average solar radiation intensity of 751.83 W/m². Furthermore, the fiber membrane exhibits a remarkable 151% elongation at break and a water contact angle of 124.5°, highlighting its suitability for use in personal wearable cooling fabrics.