Ultra-low voltage bipolar electrochemistry: a game-changer for seawater uranium extraction
Seawater uranium extraction is constrained by ultra-low uranium concentration (~3 ppb), high salinity, competing ions, and dynamic marine conditions. Electrochemical uranium extraction (EUE) offers high efficiency and controllability by promoting uranyl ion migration and reduction-deposition, but conventional EUE requires elevated voltages that trigger side reactions and limit selectivity. Recent advances in cathode materials—amidoxime, phosphate, and other uranyl-binding ligands—have improved adsorption capacity, yet most systems deposit uranium only at the cathode, underutilizing the electrochemical cell. Wang et al. (2025) introduce a bipolar EUE system that replaces the oxygen evolution reaction with low-potential copper oxidation, reducing cell voltage to 0.6 V. This enables simultaneous uranium extraction at both electrodes: at the anode, Cu(0) oxidizes to Cu(I), forming Cu–OH bonds that adsorb U(VI)O2^2+; in the presence of Cl−, Cu(I) transforms into Cu2(OH)3Cl, concurrently facilitating uranium capture. The bipolar design achieves long-term stability, selectivity against competing ions, and reduced energy consumption compared to traditional EUE systems. This breakthrough addresses the trade-off between extraction performance and energy input, offering a scalable pathway for sustainable uranium recovery from seawater.