A Sustainable Photothermal Aerogel Based on Polyphenol-Metal Chelation for Efficient Solar-Driven Seawater Desalination

The growing global demand for clean water and sustainable energy necessitates the development of eco-friendly technologies for seawater desalination. A green and efficient photothermal conversion aerogel (CFA) is developed for incorporating naturally derived chlorogenic acid (CA) and Fe3+ ions into an acrylamide (AM) matrix via chelation and freeze-drying. CFA broadens light absorption and enhances solar-to-thermal conversion efficiency. Under one sun (100 mW·cm–2) irradiation, CFA heats up to 127.4 and 63.9 °C in the dry and wet states, respectively. The water evaporation rate reaches 3.367 kg·m–2·h–1. CFA exhibits excellent stability during long-term use and repeated recycling. Even in an extreme salt environment (25 wt % NaCl), the evaporation rate remains at 3.166 kg·m–2·h–1. A small-scale desalination device confirms effective ion removal (>96% for Ca2+ and >99.9% for K+, Na+, and Mg2+), meeting WHO drinking water standards. CFA serves as a sustainable, cost-effective, and scalable solution for solar-driven desalination with potential applications in off-grid or resource-limited settings.