Harmonizing Sunlight and Architecture for Argema-Inspired Nanocellulose Aerogel Radiative Coolers via Energy Tailoring Strategy

Abstract

Passive radiative cooling is a zero-energy-consumption cooling technique, which shows great application in releasing global warming. To realize efficient daytime cooling in hot, lowlatitude regions, achieving ultrahigh solar reflectance (≥96%), thermal emissivity, and low thermal conductivity simultaneously is very important but remains a great challenge for most polymerbased radiative coolers. In this work, inspired by the micro/ nanostructure in Argema mittrei, an efficient energy tailoring strategy was proposed to design mechanically stable and biodegradable nanocellulose aerogel-based radiative coolers (CDA) with a nested pore structure for high-performance passive cooling. By constructing dual-pore structure at the micro/ nanoscale level and dual chemical structure at the molecular level by cross-linking by LiCl, the as-prepared CDA exhibits ultrahigh solar reflectance of 97%, high emissivity of 0.91, and thermal conductivity of 37.36 mW/mK, which can realize cooling efficiency of 9.3 °C at noon in a hot city (Nanjing). The simulation indicated that the interweaved dual-pore structure can enhance the structure stability and multiscattering of CDA simultaneously. Furthermore, the CDA also displayed good biodegradability, easy recycling performance, and mechanical robustness. This work shines new light on the development of advanced sustainable porous materials for thermal regulation.