2M-phase transition metal dichalcogenides: From fundamental to application

The quasi-metallic two-layer monolayer stacking with a monoclinic crystallographic system (2M) phase of transition metal dichalcogenides (TMDs) is a notable polymorph. It has unique physicochemical properties such as superconductivity, topological insulator behavior, and significant spin-orbit coupling effects. The synthesis and exploration of 2M phase TMDs not only broaden the spectrum of physical properties associated with TMDs but also herald novel prospects and formidable challenges within the realms of materials science, electronics, and the burgeoning field of quantum computing. Therefore, it is necessary to conduct a comprehensive review of the existing research findings on 2M-phase TMDs to provide valuable guidance for future development. In this review, a comprehensive overview of synthesis strategies for 2M-phase TMDs is offered. Furthermore, their novel properties, such as superconductivity and topological properties are discussed in detail and explore the application prospects in the fields of optics and catalysis. Finally, this review provides an outlook on future development directions, anticipated challenges, and potential opportunities for 2M-phase TMDs from fundamental to application. This review aims to provide in-depth insights into 2M-phase TMDs for the scientific and engineering communities and to guide further development in this emerging field.