Durable radiative cooling against environmental aging

To fight against global warming, subambient daytime radiative cooling technology provides a promising path to meet sustainable development goals. To achieve subambient daytime radiative cooling, the reflection of most sunlight is the essential prerequisite. However, the desired high solar reflectance is easily dampened by environmental aging, mainly natural soiling and ultraviolet irradiation from sunlight causing yellowish color for most polymers, making the cooling ineffective. We demonstrate a simple strategy to use titanium dioxide nanoparticles, with ultraviolet resistance, forming hierarchical porous morphology via evaporation-driven assembly, which guarantees a balanced anti-soiling and high solar reflectance, rendering anti-aging cooling paint based coatings. We challenge the cooling coatings in an accelerated weathering test against simulated 3 years of natural soiling and simulated 1 year of natural sunshine, and find that the solar reflectance only declined by 0.4% and 0.5% compared with the un-aged ones. We further show over 6 months of aging under real-world conditions with barely no degradation to the cooling performance. Our anti-aging cooling paint is scalable and can be spray coated on desired outdoor architecture and container, presenting durable radiative cooling, promising for real-world applications.