Layered 2D material heterostructures – a colloidal perspective

Abstract

The development and ongoing discovery of 2D materials and their emergent optical and electronic properties have led to intense interest in the stacking of different 2D materials into layered heterostructures. While the initial efforts focused on mechanical transfer of 2D materials and vapor-phase epitaxial growth, there is an increasing body of research on colloidal methods for the fabrication of layered heterostructures. This review gives insight into the history and development of layered heterostructures composed of stacked 2D materials, starting from the origins of 2D materials research and leading up to the current state-of-the-art methods for fabricating 2D material heterostructures. Particular attention is given to colloidal approaches, with emphasis on the importance of surface chemistry in controlling both the assembly of dispersed 2D materials and direct colloidal synthesis at 2D material interfaces to achieve well-defined heterostructures. Approaches from diverse fields of chemistry such as the synthesis of 2D Janus nanosheets, modification of interlayer spaces of 2D materials, and colloidal atomic layer deposition give insight into potential future colloidal strategies. In summary, this review provides an overview of the basics of 2D material heterostructures and their fabrication, while also suggesting future colloidal avenues for the development of hybrid nanomaterials which would greatly benefit applications in (photo)catalysis, energy storage, sensing, optoelectronics, and more.