Research On The Preparation And Electrical Properties Of Transition Metal Sulfide Complex

In recent years, research on the regulation of the electrochemical properties of inorganic nanomaterials has been become a hot spot. In this social context, transition metal sulfide are subject to researchers of all ages, due to its composition structure pluralism, rich natural reserves, significant electrical properties and simple synthetic process.Transition metal composite sulfides because of its unique electrochemical properties in different fields have been using. This paper first introduces the general preparation method of the transition metal sulfides. The electrical properties of Cu₂CdSnS₄ and CuCo₂S₄ have been studied. Based on these excellent electrical properties, their applications on the field of photovoltaic material, lithium-ion batteries have been studied.The research contents are mainly as follows: Part 1 Spray pyrolysis deposition of Cu₂CdSnS₄ thin films and solvothermal synthesis of CuCo₂S₄ nanoparticles and flower-like CuCo₂S₄ nanosheets/RGO compositesThrough the chemical spray pyrolysis technique, quaternary Cu₂CdSnS₄ semiconductor thin films were successfully deposited. Structures, morphologies, optical and photoresponse properties of the as-prepared Cu₂CdSnS₄ films were studied in details by using X-ray diffraction（XRD）, scanning electron microscope（SEM）, energy dispersive X-ray spectroscopy（EDX）, UV-vis, photoconductance measurements, etc. CuCo₂S₄ nanoparticles with sizes of 20-50 nm and flower-like CuCo₂S₄ nanosheets/RGO composites were prepared by using a one-pot hydrothermal method. The structure of CuCo₂S₄ nanoparticle and CuCo₂S₄ nanosheets/RGO were investigated by XRD and Raman spectroscopy. SEM, transmission electron microscope（TEM） images showed hierarchical structure of CuCo₂S₄ nanoparticle and CuCo₂S₄ nanosheets/RGO. Part 2 Study on the electrical properties of transition metal sulfide complexThe Cu₂CdSnS₄ thin films have the direct optical band gaps of 1.38-1.49 eV and exhibit the notable enhancement in photocurrent versus dark-current for several tens of times. The CuCo₂S₄ showed the superior electrical properties than that of the single sulfide with metal Cu or Co.It may be attributed to the synergistic effect of copper and cobalt ions. CuCo₂S₄/RGO nanosheets could slow down the polysulfide dissolution and improve the volume change of the spinel-type transitional Cu-based and Co-based metal sulfides during the cycle process. The synergistic effect between the metal sulfides and graphitized carbon materials contributed to much improvements of electrode materials kinetics and cycling stability.Part 3 Practical application of electrical properties of transition metal sulfide complexBased on the Cu₂CdSnS₄ composite sulfide semiconductor thin film has a band gap direct optical 1.38-1.49 eV of and the photoresponse current is ten times higher that of the photoelectric properties. It can be applied to photovoltaic energy materials; Due to the excellent potential to improve the volume expansion and conductive material, the ternary metal sulfides have emerged as a new class of materials for multiple sensor, capacitor and lithium ion batteries. As an anode material for the rechargeable lithium-ion batteries（LIBs）, the CuCo₂S₄ nanoparticle can offer higher electrical conductivity and richer redox chemistry than binary sulfides, as well as combine their contributions from Cu and Co ions. For the as-fabricated CuCo₂S₄ nanosheets/RGO, the graphene carbon materials not only act as the conductive network but also serve as the buffer layer for the volume collapse. CuCo₂S₄/RGO nanosheets exhibited remarkable Li-storage performance compare to the CuCo₂S₄ nanosheets.