Anisotropic Scattering‐Enhanced Radiative Cooling by Self‐Assembled Hierarchical Silk Micropyramid Arrays

Abstract

ABSTRACT Intensified global warming has highlighted the urgent need for personal radiative‐cooling textiles. Silk, a natural protein fiber, is a promising candidate for radiative cooling because of the relatively high mid‐infrared (MIR) emissivity of fibroin proteins and its microstructure‐induced solar reflectance. However, the intrinsic absorption of the fibroin protein in the ultraviolet (UV) region poses a fundamental constraint on the cooling efficacy under sunlight, and enhancing MIR emissivity via structural design remains challenging. Herein, multiscale beaded fibers and hierarchical micropyramid arrays are rationally designed to simultaneously improve UV reflectance and MIR emissivity, with the guidance of theoretical simulations based on Mie theory and finite‐difference time‐domain modeling. The target structure is fabricated via a scalable electrospinning technique, achieving a solar reflectance of 97%, with UV‐range (0.3–0.42 µm) reflectance reaching 99%, and a high MIR (8–13 µm) emissivity of 97%. When integrated into conventional cotton fabric, the engineered structure demonstrates a superior cooling effect of ∼6°C compared with that of traditional silk fabric under direct sunlight, while maintaining sufficient breathability and flexible comfort. This study presents a feasible strategy for developing high‐performance silk‐based radiative cooling textiles.