二维过渡金属硫族化合物(TMDs)具有许多优异的性能，要实现广泛的应用还有许多诸如高质量材料的合成、迁移率的提高等问题需要解决。在材料的制备过程中不可避免的会出现畴界、反位等缺陷，它们与表面/界面散射一起会直接影响载流子的迁移率，导致器件性能的降低。针对这些问题，本项目结合实验从理论上首先对二维TMDs材料中出现畴界、发生相变的机理进行系统研究，找到控制生长的关键要素，促进材料质量的提高；其次，研究新体系的稳定性、电子结构和出现的新特性，探讨衬底、杂质、电场及吸附对原子/电子结构、自旋和输运性质的影响，找到相应的调制方式；在此基础上进一步研究畴界和缺陷在敏感和催化等领域的应用基础，从电子层次探寻其敏感和催化性能的微观机理。通过该项目研究，会对不同ML-TMDs体系的特性有更深入的认识，以期实现对结构和电子性质的精确控制，为二维TMDs制备和应用提供理论依据。

Two-dimensional(2D) transition metal dichalcogenides (TMDs), with many novel properties, are excellent candidates for both fundamental research and commercial applications. But their application still faces a number of scientific and technological issues，such as the synthesis of high quality 2D material, the improvement of mobility. The existence of defects such as domain boundary and antisite is inevitable during the preparation of material. These defects, together with the surface/interface scattering, will directly affect the carrier mobility and result in a lower performance. Based on MBE growth，we shall probe physical mechanism of domain boundary and phase transition in as-grown TMDs. More specifically, the structural identity and vital condition of the defects in as-grown TMD epifilms will firstly be investigated by density functional theory. The aim is to not only understand the defects but also contain them in order to improve the quality of the samples. Second, the structural stability and electronic structures of the latest ML-TMDs will be investigated. In addition to the magnetic and carrier mobility effects brought about by substrates and defects/dopants, others such as electric field and adsorption effects will be followed as well. Thirdly，the advantages of these materials for senser and catalysis and the different routes available to tune their electronic states and active sites will be discussed. We also explore the future opportunities of these catalytic materials and the challenges they face in terms of both fundamental understanding and the development of industrial applications. This research will expectedly generate results of great scientific and practical value for future exploration of the materials in device applications.