Synergistic Bilayer-modified Electrode and Pulse Electrochemistry for Efficient Uranium Extraction from Seawater

摘要: The extraction of uranium from seawater is crucial for sustainable nuclear energy but remains challenging due to low concentration, carbonate competition, and energy-intensive processes. Herein, this study developed and systematically evaluated a novel electrode material, CF@MTPN, coupled with the energy-efficient double potential step technique (DPST) for the highly efficient extraction of uranium from seawater. CF@MTPN was fabricated through sequential self-assembly of iron-tannic acid (Fe-TA) network and an iron-phytic acid (Fe-PA) complex on carbon felt. In simulated seawater (5 mg L -1 uranyl, 2 mM Na 2 CO 3 , pH 8.1), CF@MTPN achieved rapid uranium removal efficiencies of 90.3% (potentiostatic technique, PST) and 93.3% (DPST) within 15 min, with corresponding extraction capacities of 96.12 and 99.31 mg g -1 d -1 , respectively. Notably, during the DPST process (0 V/-1.3 V), current oscillations led to the detachment of the Fe-PA layer from the control electrode CF@MPN, alongside progressive oxidation of the bare CF surface. In contrast, the introduction of an inner Fe-TA layer in CF@MTPN effectively resolved these stability issues, allowing CF@MPN to maintain its structural integrity throughout an extended DPST operation. Moreover, DPST dramatically enhanced the Faradaic efficiency by 430% over PST by effectively suppressing the competing hydrogen evolution reaction. Practical viability was confirmed through a continuous-flow experiment with 20 L of natural seawater, achieving a uranium recovery of 60.0 μg and a high extraction capacity of 3.62 mg g -1 d -1 over 5 h. This work presents a synergistic material and process solution for efficient, stable, and energy-conscious uranium extraction from seawater.