| With the development of social economy and the accelerated process of industrialization and urbanization,the demand for energy is becoming more and more urgent.However,the environmental pollution caused by fossil energy is inevitable and urgently needs to be solved.Therefore,the exploration of clean and renewable energy has attracted the attention of researchers around the world.However,the unstable supply of renewable energy has limited its wide range of applications.Therefore,it is very necessary to develop a storage system conducive to the stable use of renewable energy.Recent studies have shown that functional materials with special physical and chemical properties have great potential for development and application in the utilization of renewable energy.Transition metal chalcogenide(TMCs)materials are potential functional materials with multiple advantages.The emergence of various types of TMCs provides an important opportunity for the sustainable development of environment and economy.However,due to the complexity of the synthesis strategy,TMCs have relatively few applications in functional materials such as electrode materials and catalysts.The synthesis of some TMCs involves multi-step reactions,and the reaction process may be uncertain,which affects the properties of the materials and hinders their further application.Therefore,it is still a challenging problem to design a simple and universal method to construct TMCs with good crystallinity and chemical performance.Based on this background,the structure of TMCs was reasonably improved and optimized by means of nanostructure engineering,carbon nanophase limitation and alloying,which can be used to solve the inherent structural instability and low conductivity of TMCs and obviously improve the chemical properties.In addition,the chemical intercalation of TMCs by simple synthesis method can enrich the TMCs system and provide the possibility for the development and utilization of the new electromagnetic functional materials.The purposes of the paper are to design and synthesize new TMCs functional materials by simple chemical methods,and study their application in lithium-ion batteries,potassium-ion batteries and chemical intercalation properties.(1)N-doped carbon-coated MnSe@SnSe2 nanorods(MnSe@SnSe2@N-C)were successfully prepared by simple self-assembly nucleation,carbon coating and in-situ selenization methods.N-doped carbon layer is mainly used as a space buffer layer to restrain the volume expansion during the electrochemical reaction process and improve the stability of cycle performance,while MnSe plays an important role in the high capacity of electrode materials.MnSe@SnSe2@N-C anode material shows excellent cycle performance and long cycle stability.The MnSe@SnSe2@N-C can hand over a highly reversible capacity of 1045.8 mA h g-1 at 0.2 A g-1 after 200 cycles,the reversible capacity maintains 417.5 mA h g-1 at 2.0 A g-1 after 2000 cycles.In a word,MnSe@SnSe2@N-C is a promising anode material for lithium-ion batteries.(2)Amorphous N-doped carbon-coated FeS/SnS composites(FeS/SnS@N-C)were successfully synthesized by in-situ polymerization and vulcanization.The results of experiments and DFT calculations show that the unique structure of bimetallic sulfides and the synergistic effect of various components make FeS/SnS@N-C electrode materials exhibit excellent electrochemical properties.The reversible capacity is 796.90 mA h g-1 after 200 cycles at 0.5 A g-1,and the long cycle performance remains 278.84 mA h g-1 after 2000 cycles at 5.0 A g-1.The preparation of bimetallic sulfides by a simple synthetic route can not only enrich the types of bimetallic sulfides,but also provide a strategy for the synthesis of other bimetallic/polymetallic sulfides,selenides or phosphide composites with stable structures,which can further explore the possibility of its application in energy devices,electrocatalysis and photodetectors.(3)N-doped reduced graphene oxide coated CoSe2 nanocomposites(CoSe2@NrGO)were successfully synthesized by one-step hydrothermal method,in which CoSe2 consists of orthorhombic and cubic phases.CoSe2@N-rGO shows excellent electrochemical performance as PIBs anode material.The CoSe2@N-rGO can hand over a highly reversible capacity of 599.3 mA h g-1 at a current density of 0.05 A g-1 in the initial cycle,the reversible capacity maintains 421.0 mA h g-1 after 100 cycles at 0.2 A g-1.DFT results show that CoSe2@N-rGO can significantly accelerate the electron transfer and improve the rate performance.In addition,the internal reason why the orthorhombic CoSe2 has higher reversible capacity than the cubic CoSe2 is also discussed.The excellent rate performance and long cycle performance of CoSe2@NrGO electrode materials provide favorable help for the development of new PIBs anode materials.(4)Several FeS-derived intercalated compounds(C2H8N2)xFeS and Ax(C2H8N2)yFeS(A=Li,Na)were successfully synthesized via a novel solvothermal method.XRD results reveal that the FeS intercalated samples have the same tetragonal crystal structure as the parent FeS.After intercalation,these three as-synthesized samples do not show superconductor behavior,which is confirmed by the magnetization and the electrical resistivity measurements.(C2H8N2)xFeS exhibits paramagnetic semiconductor behavior,while the newly synthesized Ax(C2H8N2)yFeS(A=Li,Na)shows antiferromagnetic semiconductor behavior.The absence of superconductivity in these FeS-derived compounds should be closely related to the iron vacancies in the FeS layer.Consequently,this work provides new members in the ironbased family and provides further understanding on metal and organic amine cointercalated FeS materials. |
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