A synergistic coordination-reduction interface for electrochemical reductive extraction of uranium with low impurities from seawater

Electrochemical extraction of uranium from seawater is a promising strategy for the sustainable supply of nuclear fuel, whereas the current progress suffered from the co-deposition of impurities together with uranium. Herein, we constructed a synergistic coordination-reduction interface in Ni2S3 fiber with polyoxometalate CoMo6-derived amorphous CoMoOS layer (CMOS@NSF), achieving electrochemical extraction of black UO2 products from seawater. The internal sulfur of CoMoOS tailored the electron distribution, resulting in the electron accumulation of terminal O sites for strong uranyl binding. Meanwhile, the interfacial connection of CoMoOS with Ni3S2 accelerated the electron transfer and promoted the reductive properties. Such synergistic coordination-reduction interface ensured the formation and preservation of tetravalent uranium, preventing the co-deposition of alkalis in crystalline transformation. Consequently, CMOS@NSF extracted 71.55 μg of uranium from 25 L seawater, corresponding to an extraction capacity of 2.65 mg g−1 d−1. Moreover, after electrochemical uranium extraction, the UO22+ was reduced to black UO2 solid products with low impurities, facilitating the potential utilization in future.