Biomimetic superhydrophobic cotton fabrics with multistage micro-nanostructures for long-term passive radiative cooling

Passive radiative cooling (PRC) has attracted considerable attention in personal thermal management due to its zero-energy consumption and zero-pollution. However, PRC textiles in outdoor applications are susceptible to contamination, resulting in performance degradation. Inspired by the self-cleaning surface of lotus leaves, a biomimetic superhydrophobic cotton fabric for long-term passive radiative cooling was successfully fabricated by constructing ZIF-L/ZIF-8 micro-nanostructures and combining with polymethylhydrosiloxane (PMHS) coatings. This multistage micro-nanostructure significantly enhanced the optical properties of cotton fabric, increasing the solar reflectance from 64.5% to 90.4% and the infrared emissivity from 93.0% to 95.8%. Furthermore, the superhydrophobic fabric demonstrated excellent radiative cooling performance, achieving a cooling effect of 5.3 °C under solar irradiation compared with cotton fabric. In particular, the fabric exhibited superior superhydrophobicity with a water contact angle (WCA) of 162.8°, and maintained the WCA of over 150° under severe conditions such as soaking in acids, alkalis and salts, ultrasonic treatment, washing, tape peeling and abrasion. Most importantly, the fabric offers an efficient self-cleaning property, making it suitable for long-term outdoor radiative cooling. The biomimetic superhydrophobic fabric integrates radiative cooling and self-cleaning functions, providing a promising solution for the development of green, energy-saving and sustainable PRC textiles.