N/S co-doped carbon nanosheets for the efficient electrochemical extraction of uranium from seawater
Carbon-based catalysts are promising materials for the electrochemical extraction of uranium from seawater.However,their practical application is often limited by high cost and low catalytic activity.Using 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 has been developed by a low-temperature hydrothermal treatment and high-temperature carbonization.Because of their high conductivity and high catalytic activity,CNS-based electrodes can catalyze uranyl ions in seawater into easily recoverable Na2O(UO3H2O)x precipitates at-2 V,and achieve an extraction capacity of up to 3 923.7 mg g-1 with a uranium removal of 98.1％in uranium-spiked seawater(1.0×103 mg L-1).In situ Raman spectroscopy showed that a large number of uranium compounds appeared on the surface of the composite electrode within 40 min of extraction.The electrode also recovered 72.7％of the uranium in natural seawater,demonstrating excellent prospects for this application.This work provides a new approach into the design of low-cost,metal-free electrocatalysts for the efficient uranium extraction from natural seawater.
Carbon nanosheetsUranium extraction from seawaterHeteroatom dopingElectrocatalysis
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