Cellulose‐Based Passive Daytime Radiative Cooling Materials: Structures, Properties, and Applications

ABSTRACT Refrigeration is vital for modern society, yet conventional vapor‐compression systems suffer high energy consumption, significant greenhouse emissions, and miniaturization challenges. Passive daytime radiative cooling (PDRC) offers a promising eco‐friendly alternative by exploiting thermal radiation to dissipate heat through the atmospheric window (8–13 µm) into cold outer space, requiring zero energy input and enabling substantial energy savings. Cellulose, as an Earth‐abundant natural polymer, is highly attractive for PDRC due to its molecular hydroxyl groups enabling high infrared emissivity and excellent structural tunability for chemical modification. Cellulose‐based PDRC materials exhibit remarkable sustainability, diverse forms, and superior cooling performance, making them ideal for advanced thermal management. This comprehensive review details the fundamentals of solar radiation and radiative cooling, then systematically examines structure‐property relationships across various cellulose‐based PDRC materials. It discusses optimization strategies via macro/microstructural control and bioinspired design, alongside functional enhancements like coloration and self‐cleaning. Key applications in energy‐efficient buildings, smart textiles, and food preservation are highlighted, demonstrating significant cooling effects and energy‐saving potential. Finally, current challenges and future prospects for next‐generation sustainable cellulose PDRC technologies are outlined.