An Easy‐to‐Prepare Thermally Conductive Metacotton for Efficient Radiative Cooling Above Ambient Temperatures

ABSTRACT Passive radiative cooling offers a promising pathway toward sustainable development by requiring no external energy input and enabling zero carbon emissions. However, the low thermal conductivity of radiative cooling materials restricts their applicability in scenarios where operating temperatures are significantly above ambient levels. Herein, we report an effective design of a novel metacotton fabricated by coating hexagonal boron nitride ( h ‐BN) and poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVDF‐HFP) onto biomass‐derived cotton through a simple, continuous impregnation process based on non‐solvent phase separation. The resulting porous PVDF‐HFP layer improves the solar reflectance and infrared emittance of the cotton to 93.0% and 94.7%, respectively. Notably, the incorporation of h ‐BN significantly enhanced the thermal conductivity of the cotton to 1.98 W m −1 K −1 , representing a 30‐fold increase. These performance enhancements enable the woven cotton/PVDF‐HFP/ h ‐BN composite fabric to achieve an average cooling effect of ~18°C relative to pristine cotton fabric under a solar intensity of ~800 W m −2 and an additional input power density of 2000 W m −2 . Additionally, the composite fabric exhibits excellent stain resistance owing to its robust hydrophobic characteristic. Overall, this study offers novel insights and presents a straightforward yet effective strategy for achieving efficient radiative cooling in applications operating at temperatures significantly above ambient levels.