Controllable Synthesis of Crystalline 2D Graphdiyne With Tunable Thickness.

Graphdiyne (GDY) is an emerging 2D carbon allotrope composed of sp-sp2 hybridized carbon atoms. Its distinctive structural feature is the presence of sp-hybridized carbon atoms, which endow GDY with unique properties, including natural bandgap, high porosity, large specific surface area, expanded interlayer spacing, high electrical conductivity, and excellent charge carrier mobility. Achieving high crystallinity and precise thickness control is essential for unlocking the intrinsic properties of GDY. However, the irreversibility of the HEB polymerization reaction, along with side reactions and the free rotation of Csp-Csp and Csp2-Csp single bonds, limits the crystallinity of GDY. Meanwhile, axial growth induced by interlayer van der Waals forces and π-π stacking complicates thickness control. The review summarizes controllable synthesis methods for monolayer, few-layer, and multilayer GDY, as well as recent experimental advances in understanding the structural and electronic properties of GDY. It further extends to the synthesis of crystalline GDY derivatives, aiming to provide a solid theoretical and technical foundation for large-scale synthesis of crystalline and ultrathin GDY in the future.