Scalable metasurface-enhanced supercool cement
Guo Liang Lu, Fengyin Du, Zhen Wang, Feilong Wu, Wenqiang Zuo, Xiaohang Xu, Zhangyu Wu, Chang Liu, Ruizhe Yang, Yanpei Tian, Zhangli Hu, Dongliang Zhao, Chenyue Guo, Tian Li, Wei She, Changwen Miao
Abstract
Structural materials with the capability for passive daytime radiative cooling (PDRC) show promise for the sustainable cooling of buildings. However, developing durable PDRC structural materials with optical robustness, ease of deployment, and scalability remain a challenge for civil engineering applications. We synthesized a metasurface-enhanced cooling cement using a universal, scalable pressure-driven fabrication strategy during a low-carbon production process. The self-assembly of multiple-sized reflective ettringites as main hydration products toward the metasurface, coupled with hierarchical pores, guaranteed high solar reflectance (96.2%), whereas raw materials containing alumina- and sulfur-rich function groups leveraged inherent mid-infrared emissivity (96.0%). This photonic-architectured cement achieved a temperature drop of 5.4°C during midday conditions with a solar intensity of 850 watts per square meter. This supercool cement featured intrinsic high strength, armored abrasive resistance, and optical stability, even when exposed to harsh conditions, such as corrosive liquids, ultraviolet radiation, and freeze-thaw cycles. A machine learning-guided life-cycle assessment indicated its potential to achieve a net-negative carbon emission profile.