Fire Resistant Building Radiative Cooler with Synergistically Optical Selective Based on 2D/3D Cellulose/LDH Nanosheets Film for Effective Energy Conservation

Passive radiant cooling (PRC) technology has an irreplaceable position in building cooling and energy conservation due to sustainable and environmental friendly without energy consumption. However, the lack of consideration for building security in extreme weather conditions, especially in hot and overheated conditions, which propose a requirements for synergistic design of fire resistance and optical selectivity of materials. Herein, this work propose to introduce the compound (PAC) originated from phytic acid (PA) and cytosine (C) and the LDH nanosheets modified by ammonium polyphosphate (APP) into porous cellulose acetate (CA) film to obtain synergistically functionalized 2D/3D cellulose LDH photonic films (CPA films). The presence of substantial amounts of P elements effectively enhances the fire resistance of films, so that it burns without an open flame and with excellent self-extinguishing. Furthermore, the P=O and P−O in APP and PAC endows CPA films with outstanding atmospheric window emissivity via selective absorption, whose infrared emissivity is 93.68%. Meanwhile, the modified dispersive LDH increases solar radiation reflectivity to 96.15%. As a verification, building models covered with films are constructed, cooling of 6℃ be achieved and average energy saving efficiency is 22.8% through shading roof merely. Looking forward to the future, the CPA films will get a comprehensive application in buildings, 5G communication base stations, spacecraft and all equipment exposed to solar. Graphical abstract