Dual conversion pathways for efficient electrochemical extraction of uranium.

The electrochemical extraction of uranium (EEU) from wastewater is of promise to ensure the sustainable development of nuclear power, of which the practical application is limited due to the single uranium species conversion pathway. To overcome this problem, we have fabricated tungsten oxide/polypyrrole composites (W18O49/PPy) with tuned interface for double conversion pathways for EEU. The PPy has two functions: (1) to modulate the electronic structure of W18O49, resulting in a built-in electric field (BEF) that accelerates the reduction of uranium; (2) to form a conversion pathway, as the catalytic center for 2e⁻-ORR to produce H2O2 that directly reacts with UO22+ to form (UO2)O2·2H2O. The W18O49/PPy electrodes shows a high extraction capacity of 3104.25 mg g-1. With the W18O49/PPy as electrode, 15.75 mg of uranium was recovered from uranium-spiked groundwater in 16.7 hours. This work has paved a way to efficient electrochemical extraction of uranium enabled by double conversion pathways.