Upgrading of silicon slag into radiative cooling materials by controlled oxidation with oxygen carriers

Abstract

Energy saving and waste recycling are two importance for sustainability of the Earth. Radiative cooling is an effective technology to decrease cooling energy consumption. Realization of low-cost preparation of radiative cooling materials is a key for large-scale application but is still challenging. Meanwhile, growing prosperity of metallurgical industry leads to abundant silicon-containing solid wastes. In this work, for the first time, an upgrading strategy to transform siliconcontaining solid wastes into radiative cooling materials is proposed by using silicon slag as a representative raw material.To eliminate the SiC component which demonstrates strong sunlight absorption and highly chemical inertness, oxygen carriers (CeOx and SrOx)-assisted accelerated oxidation strategy is developed. Al element is introduced to modify the crystal structure of products to improve the radiative cooling performance. Blended with poly(4-methyl-pentene), a membrane with CeOx-assistant annealed product (A-SiS-Al/Ce) shows a radiative cooling power of 67.3 W m -2 . In contrast, a silicon slag membrane shows a sunlight heating power of 68.5 W m -2 due to the sunlight absorption from Si and SiC components. Energy consumption simulation indicates that the A-SiS-Al/Ce membrane can efficiently save cooling energy in wide regions with climatic parameters of temperate, hot summer with cold winter, and hot summer with warm winter.