Engineering biomimetic cellulose fabric for sustainably and durably cooling human body

It is essential and challenging to develop sustainable and durable passive radiative cooling materials for long-term effectively maintaining human thermal comfort when undergoing intensified global warming in our low-carbon society. Herein, inspired by the distinct structure-property relationship of fruits-branches in fruiter, this work designs an approach of fibrillation of cellulosic fibers (branches of fruiter) followed by in-situ synthesis of SiO 2 nanoparticles (fruits of fruiter) easily to prepare sustainable, robust, customizable, and scalable cooling cellulose fabric. Such coupling strategy of cellulosic-fiber fibrillation and SiO 2 in-situ growth strongly roughens cellulose fabric, more specifically, sufficient micro- and nano-sized cellulose fibrils and SiO 2 particles, which enables our cooling cellulose fabric to effectively reflect solar light with 97% reflectance (0.4–1.0 µm) and emit mid-infrared light with 0.97 emissivity (8–13 µm). As a result, the developed cooing cellulose fabric spontaneously cools the human body with a temperature drop of 7.4 °C in high-temperature summer. It should be noted that the developed strategy realizes extraordinary adhesion performance between nanosized SiO 2 and fibrillated cellulosic fibers , endowing cooling cellulose fabric with durable yet effective cooling distinction despite enduring 100-time mechanical washing and 100-day exposure to air, as well as high strength (∼48 MPa), desirable moisture evaporation rate and breathability . The present work demonstrates a promising strategy how durability, functionality, and customizability can be integrated in future material design.