Spontaneous uranium extraction from salt-lake water via droplet falling

Uranium (U) is essential for the nuclear power industry and plays an important role in decarbonizing the energy supply. However, concern regarding the sustainability of U supply is growing, as conventional U ore reserves are scarce and common mining practices have a notable environmental footprint. Exploring alternative U sources and developing sustainable extraction methods are therefore desired. Here we show a spontaneous U extraction strategy based on droplet falling. Specifically, naturally falling salt-lake water droplets interact with a film of aluminium–fluorinated ethylene propylene–chitosan coated on carbon felt, converting mechanical energy into electricity and driving an in situ electrochemical process for spontaneous U extraction. Electrons released at the solid–liquid interface on a superhydrophobic fluorinated ethylene propylene surface reduce U(VI) adsorbed by chitosan to U(IV), ultimately forming U(VI) precipitates. Field experiments conducted in real salt-lake environments with high salinity confirm the scalability and robustness of droplet U extraction, yielding magnesium uranate (MgU 2 O 7 ) and sodium polyuranate (Na 2 U 7 O 22 ) as the main products. A multistep device reduces the U concentration of salt-lake water from 173 μg l −1 to 34 μg l −1 (extraction efficiency of 80.3%) with minimal extraction of co-existing ions. Overall, this work offers a viable pathway to sustainable U resource extraction.