Template‐Assisted 3D‐PVDF Nanonetworks for Passive Daytime Radiative Cooling

ABSTRACT Passive daytime radiative cooling (PDRC), which dissipates heat through infrared emission to outer space while reflecting solar radiation, represents a promising strategy for reducing energy consumption in cooling technologies. Here, a template‐assisted strategy is introduced to fabricate nanostructured polyvinylidene fluoride (PVDF) radiative coolers via polymer infiltration into three‐dimensional anodic aluminum oxide (3D‐AAO) nanoporous templates. The optical properties and cooling performance of the 3D‐PVDF nanostructures are investigated with and without the AAO template. To tune the crystalline phase composition and its influence on optical response, three post‐infiltration cooling methods—natural, fast, and ultra‐fast—are applied. A UV treatment further enhances solar reflectance through photo‐oxidation‐induced whitening. The optimized free‐standing 3D‐PVDF obtained via ultra‐fast cooling exhibits an average solar reflectance of 82.4% (0.32–2.5 μm) and an infrared emissivity of 96.7% within the 8–13 μm atmospheric window. These properties correspond to a theoretical daytime cooling power density of 182.3 W m −2 under a solar irradiance of 1000 W m −2 . Outdoor measurements demonstrate a daytime temperature reduction of 12.9°C under peak solar irradiance of 962 W m −2 relative to an empty reference box. This work establishes a scalable strategy for engineering three‐dimensional polymer nanostructures for high‐performance radiative cooling and energy‐efficient building technologies.