De Novo Synthesis of Free‐Standing Flexible 2D Intercalated Nanofilm Uniform over Tens of cm²

Abstract Of a variety of intercalated materials, 2D intercalated systems have attracted much attention both as materials per se, and as a platform to study atoms and molecules confined among nanometric layers. High‐precision fabrication of such structures has, however, been a difficult task using the conventional top‐down and bottom‐up approaches. The de novo synthesis of a 3‐nm‐thick nanofilm intercalating a hydrogen‐bonded network between two layers of fullerene molecules is reported here. The two‐layered film can be further laminated into a multiply film either in situ or by sequential lamination. The 3 nm film forms uniformly over an area of several tens of cm² at an air/water interface and can be transferred to either flat or perforated substrates. A free‐standing film in air prepared by transfer to a gold comb electrode shows proton conductivity up to 1.4 × 10⁻⁴ S cm⁻¹. Electron‐dose‐dependent reversible bending of a free‐standing 6‐nm‐thick nanofilm hung in a vacuum is observed under electron beam irradiation.