Radiative Cooling PVDF Aerogels with Hierarchical Porous Structure for Building Energy Savings

Passive daytime radiative cooling technology offers a sustainable solution for building energy conservation. However, its practical implementation faces significant challenges in regions with substantial diurnal temperature variations, particularly concerning excessive nocturnal cooling. This study presents the development of polyvinylidene fluoride (PVDF) aerogels with engineered hierarchical porous structures that effectively address these limitations through integration of radiative cooling and thermal insulation mechanisms. The PVDF aerogels exhibit a sophisticated multi-scale structural system, including dual-scale pore distributions at nanometer (0.2-0.8 μm) and micrometer (2-4 μm) scales enable efficient solar spectrum scattering; abundant C-F groups at the molecular level demonstrate superior vibrational absorption characteristics within the atmospheric window (8-13 μm), resulting in enhanced infrared emission; and the mesostructured nano/micro-scale reticulated skeleton significantly augments thermal insulation performance. This hierarchical structural design endows the materials with exceptional optical and thermal properties, including solar reflectance of 96.7%, mid-infrared emissivity of 97.6%, and thermal conductivity of 0.033   W/(m·K). In practical applications, the aerogels demonstrate remarkable temperature regulation capabilities: achieving cooling of 12.1°C under solar intensity of approximately 1200   W/m², while maintaining internal temperature at 7°C even when external temperature drops to 4°C, fully demonstrating the synergistic effects of radiative cooling and thermal insulation. This study presents an innovative solution for achieving all-weather, low-energy building thermal management, contributing to sustainable architectural development.