Preparation And Electrochemical Properties Of MoS₂ And RGO/MoS₂ Electrode Materials

Molybdenum disulfide is one of the most representative materials in transition-metal dichalcogenides.It has attracted wide attention in the field of supercapacitors because of its graphene-like two-dimensional lamellar structure and good physical and chemical properties.Graphene is a two-dimensional lamellar material with good conductivity.The synergy effect of the two materials can be effectively demonstrated and the electrochemical performance can be improved by making use of the matching of the micro-morphology and crystal structure,as well as the complementary electrochemical performance.Molybdenum disulfide with different phase structure and morphology was prepared by hydrothermal method,and rGO/MoS₂ composites were successfully synthesized.The materials were characterized by XRD,SEM,BET and FT-IR.The reaction mechanism was explored.Finally,the electrochemical properties of the materials were analyzed by CV,GCD and EIS.Flower-like spheres 2H-MoS₂ was successfully synthesized by hydrothermal method using ammonium molybdate as molybdenum source and thiourea as sulfur source.The effect of urea on the crystal structure and electrochemical properties of molybdenum disulfide was investigated by changing the content of urea.XRD analysis shows that MoS₂-N?4?materials have fewer?002?stacking layers.The results of electrochemical test show that its specific capacitance is 140.8 F/g at current density of 0.5 A/g.Changing solvent types,the results show that 2H-MoS₂material has good stability in absolute ethanol,and its specific capacitance is 176.4F/g at current density of 0.5 A/g.When the current density increases from 0.5 A/g to 4 A/g,its specific capacitance decay rate is only 57.8%.Metastable monoclinic MoO₃ with low density was prepared by hydrothermal method.MoS₂ was prepared by vulcanizing MoO₃ as molybdenum source.During the vulcanization process,NH₄⁺ions produced by thiourea hydrolysis were inserted into the?002?crystal plane of MoS₂ material,resulting in lattice distortion,forcing part of 2H phase to 1T phase and increasing the conductivity of the material.When the molar ratio of MoO₃ to thiourea is 1:8,the hollow 1T/2H-MoS₂ material has better electrochemical performance,and its specific capacitance is 164.8 F/g at the current density of 0.5 A/g.MoS₂ nanorods were prepared with DMF as solvent,and MoS₂ nanotubes were synthesized by Kokendahl effect when the solvent was absolute ethanol.When the current density is 0.5 A/g,the specific capacitance are 155.2 F/g and 187.5 F/g,respectively.rGO/MoS₂ composites were prepared by two ways.First,rGO/MoS₂composites were prepared by one-step hydrothermal method.rGO provides a large number of nucleation sites for the nucleation of MoS₂.Both of them form a hollow structure in three-dimensional space,which enlarges the contact area with electrolyte.The effect of GO content on the electrochemical properties of materials was investigated by changing the GO content.Among them,rGO/MoS₂-6composite has better electrochemical performance;its specific capacitance is 202.3F/g at the current density of 1 A/g;when current density is increased to 5 A/g,its specific capacitance decay rate is only 46.6%.Secondly,the precursor MoO₃ was prepared,and then the effect of different sulfur sources on the electrochemical properties of rGO/MoS₂ composites were investigated by using the MoO₃ as molybdenum source.When the current density is 1 A/g,the specific capacitances of rGO/MoS₂-S,rGO/MoS₂-L and rGO/MoS₂-TAA composite electrode materials are 140.9 F/g,116.7 F/g and 248.9 F/g,respectively.