High-Strength Flexible Membrane with Rational Pore Architecture as a Selective Radiator for High-Efficiency Daytime Radiative Cooling

Passive daytime radiative cooling, a cooling strategy with no energy consumption, has attracted significant attention as a supplement to traditional active energy cooling techniques. However, realizing a practicable radiator with excellent spectral selectivity and strength via facile, scalable, and economical manufacturing remains a challenge. In this study, a spray-phase-separation strategy that utilizes spray and high-speed airflow to regulate the phase evolution kinetics during the evaporation-induced phase separation process for rational pore architecture is proposed. The fabricated poly (vinylidene fluoride-co-hexafluoropropene) based flexible hierarchically porous complex membrane (FHPCM) shows an excellent spectral selectivity with an average reflectance of 97.2% and 52.9% in 0.24-2.5 and 2.5-8 mu m wavelength range, respectively. In addition, FHPCM demonstrates an average emittance of 93.5% in the atmospheric window with an effective thickness of 313 mu m, thus realizing a sub-ambient radiative cooling of 14.9 degrees C and an inaccurate noontime radiative cooling power of 100 W m(-2) under an average solar intensity of approximate to 1250 W m(-2). Outdoor applications further confirm the excellent capacity of FHPCM for cooling cars and buildings, with a maximum T-cooling of 7.4 degrees C. In addition, the economical FHPCM possesses good strength (64.6 MPa), flexibility, hydrophobicity, and weatherability.