Physical properties and potential applications of two-dimensional metallic transition metal dichalcogenides

Two-dimensional (2D) metallic transition metal dichalcogenides (MTMDCs) have aroused immense interest in the fields of physics, chemistry, material science, and nanotechnology, due to their fascinating physical and chemical properties, as well as versatile application potentials in advanced nanoelectronics and energy-related fields. In this review, exotic physical phenomena in 2D MTMDCs, such as charge-density-wave (CDW) order, unconventional superconductivity, and magnetism, as well as their excellent applications in high-performance electronic devices, electrocatalytic hydrogen evolution reactions, and supercapacitors are comprehensively discussed. In particular, the first part of this review focuses on the introduction about the origin of CDW order and its thickness-dependence in MTMDCs, as well as the interplay between CDW order and superconductivity in the 2D limit. Additionally, the universal characterization methods of CDW order, superconductivity, and magnetism of 2D MTMDCs are also summarized. The second part deals with the potential applications of 2D MTMDCs in advanced nanoelectronics and energy-related fields. Finally, challenges regarding the exploration of fundamental physical properties and versatile applications are highlighted, and future research directions are also proposed.