Research On The Synthesis And Electrochemical Performance Of ZIF-67?ZIF-8 Derived Nanomaterials

Metal organic frameworks?MOFs?are an important class of inorganic-organic hybrid materials with porous structures.In recent years,MOFs have attracted more and more attention due to their use as sacrificial templates for the preparation of MOF-derived materials.Our research work mainly focuses on the optimization of the performance of such composite materials.MOFs materials can be developed as templates.In addition,developing new post-processing methods and more reasonable component control of materials play a more important and comprehensive practical role in environmental issues.In this paper,three new MOF-derived materials were synthesized by simple and rapid synthesis methods with improving the synthesis conditions.These materials are applied to supercapacitor and lithium ion battery electrode materials.1.We synthesized nano-sized ZIF-67 by simple and rapid stirring method and obtained carbon/nitrogen porous nano-materials doped with Co/Co₃O₄ by high-temperature carbonization.The morphology and size of the nanomaterials are uniform.Under the catalytic action of cobalt,the carbon elements grow outward to form a carbon nanotube structure,forming a unique three-dimensional network structure.And cobalt nanospheres are coated at the outer ends of the nanotubes.The product is used as a supercapacitor.The electrode material exhibits good electrochemical properties.The carbonized product at 800?exhibits the best electrochemical properties.As a result,the materials deliver a specific capacitance of 492 F g^-1,a small voltage drop and good rate performance.Moreover,after 1000 cycles of charge and discharge,the specific capacitance value of 96.9%can be maintained which indicates that the material has good stability and has potential application in supercapacitors.2.We obtained the bimetallic sulfide?Zn,Co?S nanocrystals with hollow nanostructures through a two-step reaction.The obtained nanomaterials have uniform size,morphology and high specific surface area.The size of materials is a hollow cube with a size of 50 nm.The material has a large specific surface area and the BET specific surface area is 251.4 m²·g^-1 by nitrogen adsorption/desorption test of the material.It exhibits good electrochemical performance as a supercapacitor electrode material.The specific capacitance is 423.3 F g^-1 at the current density of 3 m A·cm^-2.And it can maintain 59%of the original capacitance at a current density of 10 m A·cm^-2 after charge and discharge 2000cycles,indicating that the material is a potential supercapacitor material.3.We use Co²⁺-doped ZIF-8 as a precursor material to synthesize ZnS/CoS/CoS₂@N doping carbon nanomaterials with uniform morphology by a two-step convenient and environmentally friendly spray pyrolysis method.The results of analysis of its structure and morphology indicate that ZnS/CoS/CoS₂ nanocrystals are uniformly formed on the interconnected C-N framework.The electrochemical properties of the synthesized nanomaterials as negative electrode materials for lithium ion batteries were studied in detail.The test results show that the prepared composites have high reversible specific capacity and high excellent cycle performance and rate performance.The material can maintains a reversible specific capacity of 622.7 m Ah g^-1 after 200 charge/discharge cycles at a current density of 100 m A g^-1.The performance is at a higher level in the same materials.The material has great potential in the development of new lithium battery materials and are feasible for large-scale commercialization.