Monoatomic-layered carbon materials, such as graphene¹ and amorphous monolayer carbon^2,3, have stimulated intense fundamental and applied research owing to their unprecedented physical properties and a wide range of promising applications^4,5. So far, such materials have mainly been produced by chemical vapour deposition, which typically requires stringent reaction conditions compared to solution-phase synthesis. Herein, we demonstrate the solution preparation of free-standing nitrogen-doped amorphous monolayer carbon with mixed five-, six- and seven-membered (5-6-7-membered) rings through the polymerization of pyrrole within the confined interlayer cavity of a removable layered-double-hydroxide template. Structural characterizations and first-principles calculations suggest that the nitrogen-doped amorphous monolayer carbon was formed by radical polymerization of pyrrole at the α, β and N sites subjected to confinement of the reaction space, which enables bond rearrangements through the Stone–Wales transformation. The spatial confinement inhibits the C–C bond rotation and chain entanglement during polymerization, resulting in an atom-thick continuous amorphous layer with an in-plane π-conjugation electronic structure. The spatially confined radical polymerization using solid templates and ion exchange strategy demonstrates potential as a universal synthesis approach for obtaining two-dimensional covalent networks, as exemplified by the successful synthesis of monolayers of polythiophene and polycarbazole.

单原子层状碳材料，如石墨烯¹ 和非晶状单层碳^2,3，由于其前所未有的物理特性和广泛的有前途的应用，刺激了密集的基础和应用研究^4,5。到目前为止，此类材料主要通过化学气相沉积生产，与液相合成相比，化学气相沉积通常需要严格的反应条件。在本文中，我们展示了通过吡咯在可移除的层状双氢氧化物模板的受限层腔内聚合，制备具有混合五元、六元和七元（5-6-7元）环的独立氮掺杂无定形单层碳的溶液制备。结构表征和第一性原理计算表明，氮掺杂的无定形单层碳是由 pyrrole 在 α、β 和 N 位点的自由基聚合形成的，这可以通过 Stone-Wales 变换实现键重排。空间限制抑制了聚合过程中的 C-C 键旋转和链缠结，从而产生具有面内 π 共轭电子结构的原子厚连续非晶层。使用固体模板和离子交换策略的空间限制自由基聚合显示出作为获得二维共价网络的通用合成方法的潜力，成功合成聚噻吩和聚咔唑单层就是例证。