Biomimetic, Hierarchical‐Porous Composite Aerogel Fiber with Spectral Selectivity and Water Microchannels for Synergistic Radiative‐Evaporative Passive Cooling Textile

ABSTRACT Inspired by the hair structure of desert animals, the structure‐engineered aerogel fiber (SAF) has effectively prepared through the utilization of the double‐diffusion process in wet spinning. The SAF fabric exhibit high emissivity (96.1%) within the atmospheric window and high reflectivity (92.3%) within the solar spectrum, thereby effectively mitigating the impact of solar radiation on human thermal balance. Additionally, the fibers exhibit an internal porosity of ∼93.9%, which functions to reduce the penetration of external heat and facilitates the instantaneous absorption (over 80% of self‐weight) and evaporation (∼5.7 g h −1 ) of sweat through capillary effect, thereby further enhancing the dissipation of heat from human body. The continuous and scalable technical routes also endow SAFs with outstanding mechanical strength, water resistance, and breathability. Practical application tests demonstrate that the temperature of SAF fabric is ∼10.6°C lower than the commercialized cotton fabric under direct sunlight (solar irradiation: ∼1511 W m −2 ) and ∼12.0°C under the simultaneous action of direct sunlight (solar irradiation: ∼1091 W m −2 ) and simulated sweat infiltration. These results underscore the cost‐effectiveness and high performance of SAF fabric, which offers substantial solutions and broad application prospects for multifunctional textiles and evaporative and radiative synergistic cooling applications.