Stable Silicene Wrapped by Graphene in Air.

Silicene as a novel and unique two-dimensional nanomaterial attracts considerable research interest; however, obtaining free-standing silicene still poses challenges due to its instability in air. In this work, we report the synthesis of protected silicene through chemical vapor deposition (CVD), in which silicene is sandwiched by graphene (G@S@G) covered on a Cu substrate. Graphene plays the role of both a substrate and protector, which can help silicene stabilize in air. These findings were verified by means of advanced microscopic and spectroscopic investigations accompanied by density functional theory (DFT) simulations. A large area of G@S@G can be obtained and tailored in any type of shape based on the Cu film. G@S@G shows n-type semiconductor character confirmed by a field-effect transistor (FET) device.