Synthesis And Properties Research Of Cu₂S And VS₂Nanostructures

Study on structure, morphology and property of nanomaterials is an important research direction of current advanced materials. This thesis use C12S and VS2as the research object, through hydrothermal method to study the fabrication, morphology control and growth mechanism of nanostructures. The performance of field emission and photocatalysis of these structures are also studied. The main contents and results are as follows:1. Hydrothermal synthesis and annealing process of several kinds of CuxS (x=1-2) nanostructuresCu2S nanostructures with various morphologies have been synthesized by hydrothermal method With CuCl2·2H2O and (NH2)2CS as the main raw material, ethanol as solvent. The main contents include the following aspects:(1) By one step hydrothermal method, marigold-like cubic Cu2S nanostructures have been synthesized. Followed by different annealing process, monoclinic Cu2S and tetragonal Cu1.81S nanocrystals are obtained.(2) Self-mosaic flower-like Cu2S nanocrystals have been fabricated via a two-step hydrothermal method for the first time.(3) We have studied the effects of different concentrations of ethanol for the morphology and structure of Cu2S from one-step hydrothermal method. Three kinds of spherical Cu2S nanocrystals composed of different thickness of self assembled nanosheets have been synthesized.(4) We successfully synthesise the rod-like Cu2S nano structure with the assistance of CTAB and studied the effect of adding amount of CTAB on the morphology of product.(5) Following the annealing process of rod-like and self-assembly sphere-like Cu2S nanostructure, the tetragonal Cu1.81S nanostructures are obtained.(6) The influence for morphology and structure of Cu2S nanocrystal via a hydrothermal method under different concentrations of ethanol with the assistance of PVP has been studied. The nanostructures of nanosphere, carambola-shaped nanoflowers and nanorods are synthesised.2. Field emission properties of several kinds of CuxS (x=1～2) nanostructuresWe have studied the field emission properties of as-prepared CuxS(x=1～2) nanostructures. The main contents include the following aspects:(1) We have studied the field emission properties of three marigold-like CuxS nanostructures for the first time, and explained the nonlinear phenomena in F-N curve. The experimental results show that marigold-like Cu1.81S nanostructures have the obvious advantage in field emission. The turn-on field and threshold field is2.1V/μm and5.2V/μm, respectively.(2) We have studied the field emission properties of self-mosaic flower-like Cu2S nanocrystals for the first time. This structure owns more emission sites and enhanced local field. The turn-on field and threshold field is4.4V/μm and7.6V/μm, respectively.(3) We have studied the field emission properties of self-assembled nanospheres and nanorods at different concentration of ethanol. The lower work function of Cu1.81S brings enhanced field emission performance. The rod-like structure holds the current density higher stability.(4) We have studied the field emission properties of carambola-like and rod-like Cu2S nanostructures with the assistance of PVP. The experimental results show that the rod-like structure has better field emission stability than self-assembled carambola-like structure.3. Photocatalytic performance of marigold-like CuxS nanostructuresThree as-prepared marigold-like cubic Cu2S, monoclinic Cu2S and tetragonal Cu1.81S nano structures have large specific surface area, the values are21.4m2/g,20.2m2/g and23.6m2/g, respectively. Experiments show that the photocatalytic efficiency of Cu1.81S nanostructure has higher photocatalytic performance. In the process of photodegradation for1hour, the relative residual concentration is17%for MB, the relative residual concentration of the other two samples are about28%. The photocatalytic properties of Cu2S nanostructures with different crystal types have no significant difference.4. Preparation and field emission properties of layered VS2nanostructureWe use Na3VO4·12H2O and TAA powders as raw material to synthesis layered VS2nanostructure and have studied its field emission properties for the first time. The main contents include the following aspects:(1) A large number of VS2·NH3precursors have been synthesized from the hydrothermal method, layered VS2nanostructures obtained by following ultrasonic process.(2) A large number of ZnO nanoparticles have been synthesized from the hydrothermal method using CO (NH2)2and ZnCl2with the diameter of about20-30nm.(3) VS2/ZnO nanocomposite has been successfully prepared. ZnO nanoparticles distribute on the VS2surface closely.(4) We have studied the field emission properties of VS2nanosheet and VS2/ZnO nanocomposite on silicon substrate for the first time. Experiments show that the layered VS2nanostructure has excellent field emission properties. For the VS2/ZnO nanocomposite, the turn-on field and threshold field decreased and their values are1.2V/μm and2.2V/μm. The emission current stability is also increased.(5) We have studied the field emission properties of VS2nanosheet on flexible Au/PET substrate for the first time. The turn-on field and threshold field for flexible Au/PET substrate is close to the silicon substrate. VS2nanostructure has excellent research potential in the current flexible display field.