Self-healing superhydrophobic and passive radiative cooling coating fabricated from waste-derived α-hemihydrate phosphogypsum

Addressing the high energy consumption and greenhouse gas emissions associated with conventional active cooling technologies, daytime passive radiative cooling has attracted significant interest due to its zero-energy cooling characteristics. However, its practical application remains challenging due to the difficulty in balancing optical performance, fabrication cost, process complexity, and environmental durability within existing material systems. This study utilizes industrially derived α-hemihydrate phosphogypsum (α-HPG) as a functional inorganic filler to develop an SPG-DM 0.6 S composite coating with integrated cooling performance, superhydrophobicity, and self-healing capability through hydrophobic group grafting and compounding with polymethyl methacrylate (PMMA). Experimental results demonstrate that the coating achieves an average temperature reduction of 19.5°C below ambient temperature, a net cooling power of 128 W·m −2 , a WCA of 161.2°, and excellent anti-icing and self-cleaning performance. Finite-Difference Time-Domain (FDTD) simulations systematically reveal the regulation mechanism of the material's microstructure on light scattering efficiency. This work pioneers a novel approach for the high-value utilization of industrial by-products and provides an innovative solution for developing cost-effective, high-performance, and durable sustainable radiative cooling materials.