Space‐Confined Synthesis of Monolayer Graphdiyne in MXene Interlayer

Abstract Graphdiyne (GDY) is an artificial carbon allotrope that is conceptually similar to graphene but composed of sp ‐ and sp 2 ‐hybridized carbon atoms. Monolayer GDY (ML‐GDY) is predicted to be an ideal 2D semiconductor material with a wide range of applications. However, its synthesis has posed a significant challenge, leading to difficulties in experimentally validating theoretical properties. Here, it is reported that in situ acetylenic homocoupling of hexaethynylbenzene within the sub‐nanometer interlayer space of MXene can effectively prevent out‐of‐plane growth or vertical stacking of the material, resulting in ML‐GDY with in‐plane periodicity. The subsequent exfoliation process successfully yields free‐standing GDY monolayers with micrometer‐scale lateral dimensions. The fabrication of field‐effect transistor on free‐standing ML‐GDY makes the first measurement of its electronic properties possible. The measured electrical conductivity (5.1 × 10 3 S m −1 ) and carrier mobility (231.4 cm 2 V −1 s −1 ) at room temperature are remarkably higher than those of the previously reported multilayer GDY materials. The space‐confined synthesis using layered crystals as templates provides a new strategy for preparing 2D materials with precisely controlled layer numbers and long‐range structural order.