Hygroscopic Ion‐Gel Strategy Enabling Self‐Assembled Polysaccharide Fibers for Sustainable PV Cooling and Water Harvesting

ABSTRACT Atmospheric water harvesting (AWH)‐coupled photovoltaic (PV) cooling technology presents a promising approach to address the energy‐water‐food nexus. However, existing hygroscopic salt‐based AWH materials suffer from low adsorption rates and salt leakage issues. In response, we proposed a hygroscopic ion gelation strategy to fabricate κ‐carrageenan‐based superhygroscopic fibrous porous material (KCLiFPM) with high thermal stability, robust cycle durability, and reliable performance under extreme conditions. Moisture captured by KCLiFPM gradually diffuses inward driven by osmotic pressure gradients. Meanwhile, the sulfonic acid groups of KC secure the hygroscopic sites through ionic bonds, preventing displacement. This physical–chemical synergy keeps the surface hygroscopic sites unsaturated, enabling continuous and efficient AWH process. The synergistic hierarchical design endows KCLiFPM with outstanding water uptake (0.84–4.56 g g −1 , 20–90% RH) without salt leakage. Outdoor tests show KCLiFPM achieves over 10°C reduction of PV panels, ∼7% power output enhancement, and 2.7 g g −1 daily water production. Notably, we established the first exergy efficiency evaluation framework for PV cooling systems, demonstrating 11% total exergy improvement by KCLiFPM (7% from power generation and 4% from water production). This work advances both AWH material design and PV system optimization, also promising to advance the Sustainable Development Goals.