Bilayer graphene as a template for manufacturing novel 2D materials

Recent intensive research on two-dimensional materials (2DMs) rekindle the interest in the intercalation of various atoms and molecules into layered compounds as a tool to manufacture 2DMs and tune their optoelectronic, magnetic and catalytic properties. Intercalation into free-standing bilayer graphene (BLG) has received special attention, as graphene is stable, chemically inert and enables one to study the atomic structure of the intercalated 2DM using high-resolution transmission electron microscopy. It was also discovered that the protecting action of graphene sheets makes it possible to not only stabilize the encapsulated single sheets of marginally stable layered materials, but also synthesize completely new 2D systems inside BLG, which in comparison to the bulk graphite allows for easier intercalation and much larger increase in the inter-layer separation of the sheets. In this review, we summarize the recent progress in this area, with a special focus on new materials created inside BLG. We compare the experimental findings to the theoretical predictions, pay special attention to the discrepancies and outline the challenges in the field. Finally, we discuss unique opportunities offered by the intercalation into 2DMs beyond graphene and their heterostructures.