The inefficient utilization of industrial by-product phosphogypsum, coupled with the increasing global demand for cooling, has spurred the development of sustainable radiative cooling materials. Compared with conventional cooling coatings that primarily rely on expensive synthetic materials or complex fabrication processes, this study provides a promising cost-effective and sustainable route for integrating industrial solid waste valorization with zero-energy cooling technologies. In this study, we fabricated a composite coating (β-HPG@CA/SiO2@OTS) consisting of β-hemihydrate phosphogypsum (β-HPG), a derivative product of phosphogypsum, cellulose acetate (CA), SiO2 particles and octadecyltrichlorosilane (OTS) by a facile combination of blade coating and spraying, which exhibited strong solar reflectivity (90.9%), high mid-infrared emissivity (98.7%) and satisfactory superhydrophobicity (157°). The as-prepared composite achieved an ambient temperature drop of 18.7 °C under direct sunlight during sunny weather, achieving a net cooling power of 92.23 W/m2. Meanwhile, the composite coating exhibits excellent durability after prolonged immersion in strongly acidic and alkaline solutions, ultraviolet radiation and outdoor testing. Owing to its simple fabrication process and robust cooling performance, this coating shows promise for scalable production and practical outdoor applications, such as building envelopes and equipment enclosures.
Wang et al. (Mon,) studied this question.