Construction Of Defective Sulfur Catalyst For Electrochemical Extraction Uranium From Seawater

As the most important nuclear fuel for nuclear power operation,the supply of uranium is the key to ensure the sustainable development of nuclear power.However,the proven reserves of uranium ore on land can only provide about 70 years of global nuclear energy consumption.The uranium content in the ocean is nearly 1000 times that of the proven uranium reserves on land,so the technology of extracting uranium from seawater can guarantee the sustainable and healthy development of nuclear industry.As a new method of seawater uranium extraction,electrochemical seawater uranium extraction has the advantages of rapid extraction kinetics,high adsorption capacity and easy desorption.At present,electrochemical uranium extraction from seawater is faced with the problems of external power and low activity of electrode materials.Therefore,developing the electrode materials with high electrochemical active sites and highly selective uranyl coordination sites is urgently.In this paper,based on the basic principles of electrochemistry,sulfur defect,the highly active site of electrochemical reduction reaction,was taken as the research object.Through precise regulation of the defect,the efficiency and capacity of electrochemical seawater uranium extraction are improved.The following electrode materials were developed:In this paper,sulfur-terminated Mo S₂nanosheets and sulfur-doped S-Fe₂O₃nanowires with sulfur-boundary defects are successfully prepared using sulfur-based catalysts as research objects.The relationship between the structure of the sulfur-deficient catalysts and the performance of uranium extraction from seawater is studied.The two kinds of sulfur-deficient catalysts are applied to electroreduction seawater uranium extraction.The mechanism of electric reduction was studied by theoretical calculation and various characterization methods.（1）S-terminated Mo S₂nanosheets with rich electrochemically active sites were constructed by hydrothermal method as an effective electrocatalyst for binding and reduction of uranium.In the electrochemical extraction of uranium,S-terminated Mo S₂nanosheets show higher extraction kinetics and capacity than the original Mo S₂nanosheets.S-terminated Mo S₂nanosheets demonstrate uranium extraction capacity of 1,823 mg/g in 100 ppm uranium-doped seawater at an applied voltage of-3 V,and the uranium extraction rate was more than 90%.After 30 minutes of electrolysis in 100 m L real seawater containing 100 times enriched uranium（330ppb）,only 8.7 m·Wh power was consumed,showing an excellent effect of seawater uranium extraction.（2）S-Fe₂O₃nanowires were designed as an electrocatalyst for high efficiency seawater uranium extraction,and the high efficiency electrochemical reduction of uranium in seawater was realized by photoelectric conversion.In simulated seawater containing 330 ppb uranium,28.7μg U can be extracted by S-Fe₂O₃nanowires electroreduction for 30 min,and the extraction rate is up to 87%.In real seawater,after 10 cycles of electrochemical extraction and desorption,S-Fe₂O₃nanowires can concentrate 3 L seawater into 20 m L sodium nitrate solution containing U（VI）414.3ppb.At the same time,we estimate the power consumption of concentrated seawater at only 70 m W·h.At the same time,the electrochemical uranium extraction device was connected with the photovoltaic module.In 20 L real flowing seawater,the uranium deposited on the electrode could reach 31.6μg by solar power supply for 3h,and the extraction rate reached nearly 50%.In summary,the two sulfur catalysts obtained have the advantages of simple preparation process,large yield,excellent performance and good stability of electrochemical seawater uranium extraction,and have great practical application prospects,which can provide a reference scheme for solving environmental and energy problems.