Intercalation-Mediated Synthesis and Interfacial Coupling Effect Exploration of Unconventional Graphene/PtSe Vertical Heterostructures.

Vertical heterostructures formed by stacks of two-dimensional (2D) layered materials with disparate electronic properties have attracted tremendous attention for their versatile applications. The targeted fabrication of such vertical stacks with clean interfaces and a specific stacking sequence remains challenging. Herein, we design a two-step chemical vapor deposition route for the direct synthesis of unconventional graphene/PtSe vertical stacks (Gr/PtSe) on conductive Au foil substrates. Monolayer PtSe (1L-PtSe) was detected to preferentially grow at the interface of the predeposited Gr layer and the Au foil substrate rather than on the Gr surface. The concurrent effect from the strong interaction of PtSe/Au and the space confinement effect of Gr/Au are proposed to be the essential mechanisms. Particularly, this unique growth system allows us to uncover the intrinsic property of 1L-PtSe and the interfacial coupling effect using scanning tunneling microscopy/spectroscopy. Our work should hereby enable significant advances in the synthesis of 2D-based vertical heterostructures and in the exploration of their intrinsic interface properties.