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.