CO2-utilized synthetic marbles with enhanced radiative cooling

The urgent challenges posed by global warming and CO ₂ greenhouse effects have spurred extensive efforts in building material development for utilizing sequestered CO ₂ and mitigating building energy consumption. Inspired by the natural cooling effect of ancient white marble architectures, here we developed an engineered marble material (EMM) for highly efficient radiative cooling. EMM was synthesized by carbonation of γ-Ca ₂SiO ₄ through CO ₂. This process sequestered 511 kg CO ₂ per ton of γ-Ca ₂SiO ₄. EMM possessed a hierarchical porous nano structure that offered a high solar reflectivity of 95 % and a strong thermal emissivity of 97 %. The EMM coating doped with alumina and silica gel exhibited a superior cooling effect, manifested by a maximum subambient temperature drop of 8.8 ℃. The radiative cooling effect resulted in a potential annual reduction in CO ₂ emission up to 54.8 kg/m ². The radiative cooling effect of EMM was enhanced through chemical tuning that broadened the wavelength range of its thermal emission. EMM possesses coating-ability, castability, and multifunctionalities, presenting significant potential for large-scale implementation. This work opened a new way for the application of the CO ₂-utilized materials for radiative cooling in building engineering.