Liquid metal catalyzed chemical vapor deposition towards morphology engineering of 2D epitaxial heterostructures

The past decades have witnessed significant advancements in the growth of two-dimensional (2D) materials, offering a wide range of potential applications in the fields of electronics, optoelectronics, energy storage, sensors, catalysis, and biomedical treatments. Epitaxial heterostructures based on 2D materials, including vertical heterostructures, lateral structures, and superlattices, have emerged as novel material systems to manipulate the intrinsic properties and unlock new functionalities. Therefore, the development of controllable preparation methods for tailored epitaxial heterostructures serves as a fundamental basis for extensive property investigation and further application exploration. However, this pursuit presents formidable challenges due to the incomplete understanding of growth mechanisms and limited designable strategies. Chemical vapor deposition (CVD) is deemed as a promising and versatile platform for the controlled synthesis of 2D materials, especially with regard to achieving lattice matching, a critical factor in epitaxial growth. Consequently, CVD holds potential to overcome these hurdles. In this Feature Article, we present our recent breakthroughs in the controllable preparation of 2D epitaxial heterostructures using CVD. Our focus revolves around the processes of morphology engineering, interface engineering, size and density engineering, and striking the delicate balance between growth and etching. Using molten metals or alloys as primary catalysts, we have achieved remarkable control over the fabrication of graphene/hexagonal boron nitride (hBN) super-ordered arrays, enabled multistage etching of graphene/hBN heterostructures, and successfully realized the construction of graphene/MXene heterostructures. Furthermore, our research endeavors encompass both bottom-up and top-down fabrication methods, offering a novel perspective on the synthesis of 2D epitaxial heterostructures. The resulting products hold immense potential for enhancing the efficiency of critical reactions such as oxygen reduction, CO2 reduction, and hydrogen evolution reactions. By presenting our methodologies for obtaining 2D epitaxial heterostructures through CVD, we aspire to inspire fellow researchers in this field to devise more feasible and controllable fabrication techniques while also fostering the exploration of diverse heterostructure configurations. Together, these advancements will undoubtedly pave the way for further breakthroughs in atomic manufacturing and novel applications.