Intercalation-Mediated Synthesis and Interfacial Coupling Effect Exploration of Unconventional Graphene/PtSe2 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-PtSe2 vertical stacks (Gr/PtSe2) on conductive Au foil substrates. Monolayer PtSe2 (1L-PtSe2) 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 PtSe2/Au and the space confinement effect of Gr/Au is proposed to be the essential mechanism. Particularly, this unique growth system allows us to uncover the intrinsic property of 1L-PtSe2 and the interfacial coupling effect using scanning tunneling microscopy/spectroscopy (STM/STS). Our work should hereby enable significant advances in the synthesis of 2D-based vertical heterostructures and in the exploration of their intrinsic interface properties.