Study Of Molybdenum Disulfide Composites Synthesis And Photocatalytic And Lithium Storage Properties

With the development of human society,a lot of serious problems about environmental pollution and energy crisis have increasingly brought,which urgently need research new and efficient materials for solve these two imminent problems at the same time.As an important component of transition metal sulfide,due to its special graphene-like structure and excellent photoelectric properties,molybdenum disulfide（Mo S₂）has been widely applied in the fields of photocatalysis and electrochemical energy storage.However,single-component Mo S₂ has many shortages.For example,Mo S₂photocatalytic efficiency and service life has been affected because of the photoelectron-hole pair（h⁺/e^-）rapid recombination due to its narrow band-gap,which influenced Mo S₂wide range application.In the field of electrochemical energy storage,although Mo S₂ has high theoretical specific capacity,volume expansion during the charging and discharging process owing to lithium ions embedded into Mo S₂layer,which made capacity quickly decrease,so that cannot up to battery standard with high specific capacity and long life.Based on the above statements,Mo S₂ composite materials as the object target have been researched in this paper.We investigated applications about Mo S₂ composite materials in the field of organic pollutants and antibiotics photo-degradation and lithium-ion battery,respectively.The main contents of this paper are as follows:1.Ternary Cd Mo O₄@Cd S/Mo S₂ composite catalysts were precisely synthesized by two-step hydrothermal method,small biomolecular glycine used as surfactant and morphology control agent.Field emission scanning electron microscopy（FE-SEM）analysis observed that Cd Mo O₄@Cd S composite nanoparticles with diameters of 400-500 nm have been uniformly grown on the surface of Mo S₂microspheres.The chemical composition of Cd Mo O₄@Cd S/Mo S₂ were further studied by X-ray diffraction（XRD）,high resolution transmission electron microscopy（HR-TEM）and X-ray electron energy spectrometry（XPS）.Photocatalytic efficiency of Cd Mo O₄@Cd S/Mo S₂ were evaluated by the degradation experiments of organic pollutants Rhodamine B（Rh B）and tetracycline（TC）under visible-light.Photo-degradation Rh B and TC efficiency of the 30 wt%Cd Mo O₄@Cd S/Mo S₂ sample was92.88%in 100 minutes and 99.69%in 60 minutes,respectively.Active radicals capture experiment and EPR test results have indentified that hole（h⁺）and superoxide radical（·O₂^-）were the main active species in photocatalysis process.Finally,the photocatalytic mechanism of Cd Mo O₄@Cd S/Mo S₂ was investigated by UV-DRS and Mott-Schottky tests.It was found that the electrons transfer could be accelerated and photo-generated electron-hole pairs separation could be promoted due to the Cd Mo O₄ exist,which improved photocatalytic activity of Cd Mo O₄@Cd S/Mo S₂.2.Mo S₂ coated with Carbon fiber（C@Mo S₂）flexible self-supporting electrode materials were synthesized by hydrothermal method,electrospinning technology and in-situ carbonization technology.Mo S₂ nanospheres with diameter of 150-250 nm were closely coated in carbon fiber with diameter of 500-900 nm,which observed by FE-SEM and TEM.Mo S₂ both have 1T phase and 2H phase in C@Mo S₂ flexible film materials were confirmed by XRD,Raman and HR-TEM.A sandwich electrode material Mo S₂/C@Mo S₂ was further constructed by hydrothermal reaction on the basis.Effects of C@Mo S₂ flexible self-supported electrode made by different parameters adjustment on the lithium storage performance were investigated.When the amount of Mo S₂ was 10%and the voltage was 18 k V,the 10 wt%-CM18 flexible self-supported electrode,which were prepared by electrospinning and in situ carbonization process,has better lithium storage performance.Furthermore,influences about mass change of10 wt%-CM18 self-supported electrode on the lithium storage performance have been studied.The results were found that specific capacity of the electrode was higher when the mass of the electrode was lighter,but specific capacity tended to be stable with electrode mass increased.After 500 cycles at 1 A·g^-1 current density,the specific capacity of 10-CM18-0.1 sample could still reached 1451.6 m Ah·g^-1,and the capacity retention rate was 74.23%.In addition,the rate performance test under different current densities has shown that the 10-CM18-0.1 could still maintained 1160 m Ah·g^-1 specific capacity under 2 A·g^-1 high current density.C@Mo S₂ flexible self-supported electrode lithium embedding/delithium mechanism was further studied by cyclic voltammetry curves and electrochemical impedance tests.Ions and electrons transport accelerated and battery capacity improved because of the unique carbon fiber coated Mo S₂ flexible membrane structure.On this basis,Mo S₂/C@Mo S₂ sandwich structure was prepared by Mo S₂ further loaded on the surface of C@Mo S₂.Unfortunately,the flexibility of Mo S₂/C@Mo S₂ was destroyed by load Mo S₂,so could not be formed self-supporting electrode.