Synthesis and Application of Graphene and Its Related Two-dimensional Transition Metal Chalcogenide
Author:Gao Zhen Fei
Supervisor:li yong feng zhang li qiang
The discovery of graphene has created an upsurge of research on two-dimensional materials in the scientific community.Due to its unique two-dimensional structure,atomic layer thickness and novel physical properties,it has given application potential for graphene in various fields.How to effectively develop the broad application of graphene,or use the combination of graphene and other materials to exert the excellent characteristics of graphene,provides us with a broad research space.As another star material in the two-dimensional material family,the transition metal dichalcogenide(TMD)has become a research hotspot due to its diversity of properties and structures.The chemical vapor deposition(CVD)method is the most commonly used method for preparing such materials.However,some TMDs still fail to realize the growth of large-area,high-crystalline single or multi-layer samples using this method.This provides us an opportunity to develop a new high-quality preparation method for two-dimensional materials.Based on the above,this paper starts with the application of graphene,optimizes the process of compounding graphene with other materials,and systematically discusses the role of graphene in different applications.At the same time,we have also developed the atmospheric pressure CVD method to fabricate single-layer and multi-layered titanium disulfide.The main content of the paper is as follows:Application of graphene oxide reduction: A crumpled reduced graphene oxide thin film photodetector was successfully prepared by spray pyrolysis methode.The as-prepared photodetectors exhibit excellent stability of light response and transient photocurrent response.In addition,by compounding zinc oxide and lead sulfide quantum dots to enhance the light absorption,the composite nanostructured photodetectors exhibit approximately four times the increase in photocurrent and broadband photodetection characteristics,with a photoresponse of 0.12 A/W.The combination of semiconductor photocatalysts with graphene can effectively improve the separation efficiency of photogenerated carriers(electron-hole pairs)on the photocatalyst surface.In this paper,we prepared a high-performance bulk photocatalyst composed of three-dimensional structured copper oxide nanowires and nitrogen-doped reduced graphene oxide.Furthermore,we discussed the detailed machenism of the nitrogen-doped graphene on the surface of semiconductor catalyst by enhancing the photocarriers separation efficiency.Application of CVD grown graphene: We have prepared a flexible transparent conductive film of Ga-doped zinc oxide(GZO)/graphene/PET multi-layer structure at room temperature.The film has 75% transparency and 721 Ω/sq of surface resistance under 550 nm visible light.Under tensile and bending strains,the electrical conductivity of the composite structured film did not decrease sharply with the cracking fracture of the surface GZO layer.Graphene,as a thin film interlayer,can effectively improve the application stability of the flexible transparent conductive film.Finally,we developed an modified atmospheric CVD method to synthesize a large-area,high-quality monolayer titanium disulfide.By using a three-zone tube furnace,we can precisely control the volatilization rate and timing of metal source and sulfur source.The results show that by adjusting the growth kinetic conditions(temperature,air flow,etc.),we can operate with a relatively low temperature.The monolayer two-dimensional titanium disulfide with high crystalline quality can be prepared,and the shape of the titanium disulfide nanosheets can also be controlled by changing the substrate.