Preparation Of Graphene/MoS₂ Composites And The Optimal Regulation Of Their Electrosorption Properties

The scarcity of water resources has increasingly deepened the influence of countries around the world,and how to effectively treat salty wastewater has become an urgent environmental problem to be solved.Traditional desalination methods have been developed for many years,and certain research progress has been made,but they all have unavoidable shortcomings.Therefore,it is urgent to develop new efficient and environmentally friendly desalination methods.Electro-adsorption technology?CDI?is an emerging electrochemical desalination technology.Its high removal rate and high energy efficiency are the needs of the development of the times,but its adsorption performance depends largely on the electrode material.Compared with traditional carbon materials,graphene has a higher theoretical specific surface area,higher electrical conductivity,and excellent mechanical strength.It is considered to be an ideal electro-adsorption electrode material,its high conductivity and high transition metal sulfide MoS₂ The combination of density can theoretically obtain a highly conductive and dense electrode material for CDI desalination.At present,research and reports on the desalination performance of rGO/MoS₂ composites are still insufficient.In this paper,the rGO/MoS₂ composite was prepared,and its microstructure and morphology were targeted for design and optimized control,in order to obtain CDI electrode materials with good adsorption performance and stability.The main research work is as follows:?1?The effects of different volume ratios of water and ethanol in solvent on the microstructure and electrochemical properties of rGO/MoS₂ composite were investigated and it has a larger layer spacing than pure MoS₂.When the volume ratio of water and ethanol is 2:1,the 3D flower-like structure of MoS₂ is disorderly wound and convoluted on the rGO substrate to form rGO/3D flower-like MoS₂ composite.According to the constant current charge-discharge test,the rGO/MoS₂ complex?MSG-1?prepared when the volume ratio of water and ethanol was 2:1 showed the maximum specific capacitance,reaching 198.6 F/g.The excellent electrochemical performance of MSG-1 was due to its specific structure and the synergistic effect of graphene and MoS₂.The electrosorption of Na⁺on the rGO/MoS₂ electrode follows a pseudo-first-order kinetic model.The isotherm simulation data shows that the Langmuir isotherm is more suitable than the Freundich isotherm,which indicates that monolayer adsorption is dominant.The largest specific capacitance indicates that MSG-1 has the best charge storage performance,and also exhibits excellent CDI performance.The maximum desalination capacity is 16.82 mg/g at 200 mg/L Na⁺solution and an operating voltage of 1.0 V;?2?rGO/MoS₂ containing defects were prepared by a simple chemical etching method with the solvent water-alcohol ratio of 2 as the raw material,and the influence of defect degree on the microstructure,electrochemical property and electroadsorption property of the composite was investigated.After adding Na BH4to etch,it will continuously generate hydrogen,which will affect the van der Waals force between the layers and change the layer spacing.The etched rGO/MoS₂?d-rGO/MoS₂?composite surface will carry more negative charges,and has better wettability and improved electrochemical performance.The compound prepared when the addition amount of Na BH₄ is 5 g?d-rGO/MoS₂-5?not only has lower internal resistance and charge transfer resistance,but also has better charge storage performance,and the specific capacitance reaches 305.6 F/g.After etching,the adsorption time of Na⁺was longer and the equilibrium adsorption amount increased,which was in line with the pseudo-first-order kinetic model.Moreover,the adsorption capacity of d-rGO/MoS₂-5 composite was larger,reaching 21.85 mg/g.