Property Explorations and Applications of 2D Transition Metal Dichalcogenides Through Phase Engineering.

2D transition metal dichalcogenides (2D TMDCs) are a group of materials possessing rich phases and versatile phase-dependent properties, such as ferroelectricity, superconductivity, and magnetism. Phase engineering has been progressively pursued for propelling such novel property explorations and applications. Herein, this review summarizes recent advances in the phase engineering of 2D TMDCs from the perspectives of synthesis and property exploration. The electronic property modulations, novel applications in surface-enhanced Raman scattering and electrocatalysis, and fundamental properties regarding superconductivity, ferroelectricity, and self-intercalation-induced magnetism will be reviewed. Diverse phase engineering strategies for synthesizing distinct phases of 2D TMDC, covering direct syntheses (e.g., chemical vapor deposition, molecular beam epitaxy, and colloidal synthesis) and phase transitions (e.g., seed epitaxy, salt-assisted method, and electrochemical exfoliation) will be discussed. Finally, future challenges and opportunities are proposed regarding the thermal stability control, phase patterning, twist angle control, and theoretical predictions of new phases. Overall, this review provides a comprehensive summary and outlook of phase engineering strategies in 2D TMDCs and inspires in-depth explorations into the properties and applications of unconventional 2D TMDC phases.