Synergistic Design of Radiative and Evaporative Cooling: A Nanofiber Membrane-Hydrogel System for High-Performance Passive Cooling

Abstract Passive cooling technology that integrates radiative and evaporative cooling offers distinct advantages, including zero energy consumption and enhanced cooling performance, and has therefore attracted increasing attention. Inspired by the synergistic cooling mechanism, this work proposes a composite cooler fabricated by combining a polyacrylamide (PAM) hydrogel with an excellent swelling ratio (∼1800%) and a thermoplastic polyurethane (TPU)-based nanofiber membrane exhibiting high solar reflectivity (∼85%). Experimental results demonstrate that the resulting TPU/PAM composite cooler achieves a temperature drop of approximately 27 °C. In comparison, the single-layer TPU film and the PAM hydrogel alone achieve temperature reductions of ∼12.3 °C and ∼23 °C, respectively. Furthermore, the composite cooler shows significant potential for applications in building thermal management, vehicle operation, and decelerating fruit oxidation. This work provides a perspective for low-energy passive cooling of buildings.