MOF-Based Hierarchical Bilayer Membranes for Radiative Evaporative Cooling in Fruit Preservation
The global cold chain consumes vast amounts of energy and emits greenhouse gases, while many regions lack proper refrigeration. To address this, we developed a dual-layer electrospun membrane (PZ-PML) for energy-free fruit preservation. The top PVDF-HFP/ZIF-8 layer offers 97.64% solar reflectance and 92.5% mid-infrared emissivity, providing 70 W/m2 radiative cooling. The bottom PAN/MIL-101/LiCl layer, with 2.18 g/g water uptake at 80% RH, delivers ~156 W/m2 evaporative cooling, lowering surface temperature by 6.1 °C under ~400 W/m2 irradiation. The membrane also shows ≥99% antibacterial efficiency against E. coli and S. aureus. Applied to strawberries, it reduced dehydration to 20.2% after 9 days, compared to 68.2% and 74.4% in controls. Additionally, it demonstrates durability, superhydrophobicity, and UV stability. This scalable solution offers energy-free fruit cooling, reducing postharvest losses while maintaining quality and safety.