Few-Layered Graphyne Growth by an On-Surface Coupling Reaction via Alkynyl Vapour Deposition

Abstract: A graphyne (GY) family composed of the triple (sp) and double (sp2) bonds-hybridized carbon atoms is a promising allotrope of carbon for the development of nanoscale electronic devices. Unlike graphene, the GY family containing carbon sp bonds remains an unsolved problem in efficient two-dimensional (2D) growth due to monomer instability and side reactions. Herein, we synthesize GY into a single 2D layer by chemical vapor deposition (CVD) at low temperatures preventing unexpected reactions, using 1,3,5-tribromo-2,4,6-triethynylbenzene (TBTEB). The CVD-grown GY via a surface-confined coupling between TBTEB monomers on a copper surface can be rid of either one-dimensional (1D) or three-dimensional (3D) growths via side reactions. The CVD-grown GY exhibits a hexagonal lattice structure containing a single sp-carbon bond in a link between two adjacent hexagons, consisting with the structure of gamma-GY. This work opens a new avenue for synthesizing large-scale and single-crystalline GY that can be capable of versatile applications with theoretically expected properties.