Thermal Rectification in Gradient Microfiber Textiles Enabling Noncontact and Contact Dual‐Mode Radiative Cooling

Abstract Radiative cooling textiles characterized by high solar scattering and significant mid‐infrared emission properties present a promising energy‐efficient solution for cooling objects exposed to high temperature and direct sunlight conditions. However, the inherent porous structure and thermal insulating properties of textiles pose challenges in effectively cooling self‐heated objects. Herein, the fabrication of an ultra‐flexible is presented, gradient‐structured microfiber composite textile using a filtration‐induced entrapment and hot‐pressing method. This textile features a unique concentration gradient of thermally conductive boron nitride nanosheets across its thickness, leading to a gradient distribution of stacking pore sizes. This gradient configuration induces multiple Mie scattering across the entire spectrum of incident sunlight, thereby achieving an impressive solar reflectance of up to 97.3%. Moreover, this textile demonstrates a thermal rectification factor of 31.8%, enabling efficient dual‐mode radiative cooling capabilities in both noncontact and contact scenarios. In noncontact cooling scenarios, this textile effectively reduces the temperatures of unheated and self‐heated enclosed spaces by 9.2 and 8.7 °C, respectively, outperforming typical textiles. Additionally, this textile shows enhanced radiative cooling capabilities in contact cooling scenarios, lowering the temperature of underlying self‐heated objects by 8.6 °C compared to typical textiles.