Synthesis Of Nanoscaled Molybdenum Oxides And Carbides As Anode Materials For Lithium-ion Batteries And Electrocatalysts For Hydrogen Evolution Reaction

Mo-based compounds have a variety of valence states and chemical properties.As materials for electrochemical energy storage and catalysis,their unique physical and chemical properties,such as electrical conductivity,mechanical and thermal stability,make them a research hotspot.In this paper,molybdenum-based nanomaterials oxides and carbides are taken as the main research objects to study their preparation,structural regulation and optimization of lithium storage and hydrogen evolution reaction performance.Specific content as follows:1?CoMoO4-Co3O4Herein,hierarchical lamellar CoMoO4-Co3O4 heterostructures are synthesized via a facile one-step hydrothermal followed by annealing method.The obtained heterostructures are composed of lamellar CoMoO4 nanosheets,where Co3O4 nanoflakes are perpendicular growth into array on the surface of nanosheets.The formation mechanism for hierarchical lamellar CoMoO4-Co3O4 heterostructures is clarified,and the sequential precipitation of CoM0O4-Co3O4 precursors is proposed as the main mechanism.Furthermore,the solvent thermal reaction time greatly affect the morphologies of the obtained CoM0O4-Co3O4 heterostructures.The lamellar structures with smooth surface,hierarchical lamellar CoMoO4-Co3O4 heterostructures with rough surface and single layer nanosheets with rough surface can be obtained by tuning the reaction time.The obtained hierarchical lamellar CoMoO4-Co3O4 heterostructures demonstrate excellent rate performance,Li-cycling behavior in the voltage range of 0.01-3.0 V,and the enhanced electrochemical properties for anode materials.2?MoxCHerein,three kinds of molybdenum carbide hollow nanospheres with stable structures were prepared by controlling annealing temperature.Firstly,utilizing previously reported Mo-glycerate(MoG)spheres as the precursor,the obtained MoG solid spheres react with dopamine hydrochloride(Mo-DPA)in the presence of ammonia.Under such alkaline condition,dopamine polymerizes at the surface of MoG spheres while the MoG solid spheres are slowly etched.The hollow nanosphere structure with carbon polymer was formed.Then,three kinds of hollow molybdenum carbide structures with carbon coating,P-Mo2C/Mo,?-Mo2C and ?-MoC were successfully obtained after annealing at different temperatures.Finally,after the electrochemical hydrogen evolution reaction test of the three kinds of molybdenum carbide hollow spheres,the three kinds of molybdenum carbide hollow spheres all showed significant electrochemical hydrogen evolution performance,which can be attributed to their unique composition and structure.