Hierarchical Ethyl Cellulose Films With Exceptional UV Stability Enabling Highly Efficient Daytime Radiative Cooling

Flexible radiative cooling materials can dissipate heat from objects without energy consumption, offering a sustainable approach to thermal management. Current research lacks radiative cooling materials combining eco-friendliness and UV resistance. We develop a flexible and eco-friendly ethyl cellulose (EC) film with durable UV resistance via a scalable electrospinning approach, enabling efficient daytime radiative cooling. The EC film has an average solar reflectance of 97.4 % (0.3–2.5 μm) and a mid-infrared emittance of 89.4 % (8–13 μm), resulting in a theoretical radiative cooling power of 145 W m⁻². Therefore, under the solar radiation of 961 W m⁻², the EC film achieves a significant temperature reduction of about 10.4 °C below the ambient temperature. Since the electron-donation effect of the ethyl group, the ethyl groups can reduce the reactivity of hydroxyl groups and generate sacrificial carbon-centered free radicals to enhance the UV stability of the EC film. After 600 h of continuous UV irradiation at 0.7 kW m⁻², the EC film exhibits an average solar reflectivity of 96.9%. Moreover, the EC film degrades naturally in soil within ≈8 months. The excellent refrigeration performance, UV stability, and eco-friendliness of the EC film make it highly promising for diverse refrigeration applications.