N/S Co-doped carbon nanosheets for efficient electrochemical extraction of uranium from seawater

Carbon-based catalysts one of the most promising materials for electrochemical extraction of uranium from seawater. However, the practical application of these materials is often limited by high costs and low catalytic activity. Herein, by utilizing low-cost polystyrene sulfonic acid resin and melamine as raw materials, a class of nitrogen and sulfur co-doped carbon nanosheets (CNSs) with high catalytic activity are developed through low-temperature hydrothermal treatment and high-temperature carbonization. Benefiting from the high conductivity and high catalytic activity, the CNSs based electrodes can catalyze uranyl ions in seawater into easily recoverable Na₂O(UO₃·H₂O)_x precipitates at −2 V, and achieve an extraction capacity of up to 3923.7 mg g⁻¹ with a uranium removal ratio of 98.1% in uranium-spiked seawater. In situ Raman spectroscopy indicates that a large number of uranium compounds appears on the surface of the composite electrode within 40 min of electrochemical uranium extraction. Notably, the electrode can still recover 72.7% of the uranium in natural seawater, demonstrating excellent application prospects. This work is hoped to provide new insights into the design of low-cost, metal-free electrocatalysts for efficient uranium extraction from natural seawater.