Covalent organic frameworks (COFs) can exhibit high specific surface area and catalytic activity, but traditional solution-based synthesis methods often lead to insoluble and infusible powders or fragile films on solution surface. Herein we report large-area –C=N– linked two-dimensional (2D) COF films with controllable thicknesses via vapor induced conversion in a chemical vapor deposition (CVD) system. The assembly process is achieved by reversible Schiff base polycondensation between PyTTA film and TPA vapor, which results in a uniform organic framework film directly on growth substrate, and is driven by π‐π stacking interactions with the aid of water and acetic acid. Wafer-scale 2D COF films with different structures have been successfully synthesized by adjusting their building blocks, suggesting its generic applicability. The carrier mobility of PyTTA-TPA COF films can reach 1.89 × 10−3 cm2 V−1 s−1. When employed as catalysts in hydrogen evolution reaction (HER), they show high electrocatalytic activity compared with metal-free COFs or even some metallic catalysts. Our results represent a versatile route for the direct construction of large-area uniform 2D COF films on substrates towards multi-functional applications of 2D π‐conjugated systems.
The preparation of large‐area 2D conductive metal–organic framework (MOF) films remains highly desirable but challenging. Here, inspired by the capillary phenomenon, a face‐to‐face confinement growth method to grow conductive 2D Cu2(TCPP) (TCPP = meso‐tetra(4‐carboxyphenyl)porphine) MOF films on dielectric substrates is developed. Trace amounts of solutions containing low‐concentration Cu2+ and TCPP are pumped cyclically into a micropore interface to produce this growth. The crystal structures are confirmed with various characterization techniques, which include high‐resolution atomic force microscopy and cryogenic transmission electron microscopy (Cryo‐TEM). The Cu2(TCPP) MOF film exhibit an electrical conductivity of ≈0.007 S cm−1, which is approximately four orders of magnitude higher than other carboxylic‐acid‐based MOF materials (10−6 S cm−1). Other wafer‐scale conductive MOF films such as M3(HHTP)2 (M = Cu, Co, and Ni; HHTP = 2,3,6,7,10,11‐triphenylenehexol) can be produced utilizing this strategy and suggests this method has widescale applicability potential.
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