Photothermal Promotion of Uranium Extraction from Seawater with Self‐Supporting Functionalized Polyurethane Sponge

Extracting uranium from seawater at an ultralow concentration (3.3 ppb) is a promising approach for the sustainable development of nuclear energy, which presents a critical obstacle. Herein, we report a photothermal‐promoted extraction strategy by utilizing a self‐supporting covalent organic polymer‐based sponge (named TpPa‐SO 3 H@PU sponge) composed of black polyurethane sponge substrate and β ‐ketoenamine covalent organic polymer with sulfonic acid groups. The adequate water transport induced by photothermal conversion significantly improves the mass transfer of uranyl ions. Compared with the dark condition, a 25.8% increase of uranyl extraction capacity, up to 36.4 mg g −1 , is achieved under simulated sunlight irradiation. In 1 L of seawater, 83.8% of uranyl is extracted after exposure to natural sunlight for 48 h. Furthermore, 20 mL of concentrated solution containing 1 ppm uranyl is obtained from 9 L seawater after nine consecutive extraction‐elution cycles. These results demonstrate that TpPa‐SO 3 H@PU sponge holds significant potential for practical uranium extraction from seawater under natural sunlight.