High-efficiency electrochemical uranium extraction from seawater enabled by a coordination modification strategy involving Fe

Abstract

Uranium extraction from seawater is crucial for sustainable nuclear energy but remains challenging due to its low concentration, carbonate competition, and energy-intensive processes. In this study, we developed and systematically evaluated a novel electrode material, CF@MTPN, coupled with an energy-efficient double potential step technique (DPST). CF@MTPN was fabricated by sequentially self-assembling iron–tannic acid (Fe–TA) networks and iron–phytate (Fe–PA) complexes on a carbon felt substrate. In simulated seawater (5 mg per L uranyl, 2 mM Na₂CO₃, and pH 8.1), CF@MTPN achieved high uranium removal efficiencies of 90.3% using the potentiostatic technique (PST) and 93.3% using the DPST within 15 min, corresponding to uranium extraction capacities of 96.12 mg g⁻¹ d⁻¹ and 99.31 mg g⁻¹ d⁻¹, respectively. Notably, by suppressing the competing hydrogen evolution reaction, the DPST achieved a faradaic efficiency 4.3 times higher than that of the PST. It is noteworthy that although the DPST-induced current oscillations caused phytate hydrolysis in the Fe–PA layer of the control electrode (CF@MPN), the inner Fe–TA layer in CF@MTPN effectively mitigated this stability issue, thereby ensuring structural integrity. The practical viability was confirmed through a continuous-flow experiment using 20 L of natural seawater, which yielded a uranium recovery of 60.0 µg. This work presents a synergistic material and process solution for efficient, stable, and energy-conscious uranium extraction from seawater.