Abstract
Due to the atomically thin layered-structure and high surface to volume ratio, two dimensional (2D) transition metal dichalcogenides (TMDCs) have been emerged as potential candidates for the next-generation nanoelectronics and energy storage applications. Different from the bulk materials, the performances of ultrathin 2D materials for their applications are highly dependent on their interface and crystalline structures. Therefore, rational design and engineering of the interface and crystalline structure play an important role in modulating the properties of TMDCs and hence improving their performances for applications. Besides, a controllable synthesis method in producing nanostructured TMDCs with precisely controlled parameters is critically important for industrial applications. Tremendous works on the controllable synthesis of monolayer TMDCs with high quality and impressive efficiency have been reported, including synthesis mechanism, structural design, and characterization of TMDCs. However, the lack of consistent synthesis method and growth mechanism investigation to produce large-area and high-quality 2D TMDCs have induced great difficulties in large-scale industrial applications. In this thesis, we propose different modifications in chemical vapor deposition (CVD) such as precursor sources and growth conditions, to synthesize a diverse range of polymorph and optimize the optical properties, catalytic abilities, electrochemical performances, and charge transfer efficiency of 2D TMDCs for various applications. First, by deep investigation on the transition metal precursor such as the stoichiometry state of transition metal oxide precursor and the use of alternative metal foil precursor sources, large-scale and high quality monolayer TMDCs can be achieved. Our contributions further have far-reaching implications for tailoring morphology and ii crystal quality of TMDCs monolayer by the deep investigation of the effect of transition metal precursor on the CVD growth mechanism. In the following work, we further focus on developing an in-situ doping CVD method to design 2D-material-based electronics and catalysts of novel functionalities. Using CVD in-situ doping, our findings reveal the possibility of fine-tuning the optical, electronics, and chemical properties of TMDC monolayer. The combined advantages of the unusual physics and chemistry by the in-situ CVD doping technique further endorse the 2D TMDCs with novel functionalities for electronics and catalysis applications. Lastly, we further implement the CVD as an alternative to produce large-scale atomically thin TMDC on other substrate such as conductive carbon cloth for energy storage application. Large-scale production of ultrathin TMDCs on other growth substrate is critical for the exploration of energy storage applications. With the proved competitive performance, the proposed CVD-grown highly crystalline and atomically thin TMDCs on carbon cloth serves as effective electrode/electrolyte interlayer for Li-S battery. Our approach reveals the possibility of tailoring the morphology, optical property, chemical behavior and crystal quality of atomically thin TMDCs by the deep investigation of the CVD growth mechanism. And our works further suggest the great potential of TMDCs for applications via rational design and engineering of the interface and crystalline structure of atomically thin TMDCs materials by CVD approach.