Liu Minghui, Liu Youxing, Dong Jichen, Bai Yichao, Gao Wenqiang, Shang Shengcong, Wang Xinyu, Kuang Junhua, Du Changsheng, Zou Ye, Chen Jianyi, Liu Yunqi
Beijing National Laboratory for Molecular Sciences, Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, 100190, Beijing, PR China.
University of Chinese Academy of Sciences, 100049, Beijing, PR China.
Nat Commun. 2022 Mar 17;13(1):1411. doi: 10.1038/s41467-022-29050-9.
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 cm V s. 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.
共价有机框架（COFs）可展现出高比表面积和催化活性，但传统的基于溶液的合成方法往往会导致不溶性和难熔性粉末，或在溶液表面形成易碎的薄膜。在此，我们报道了通过化学气相沉积（CVD）系统中的气相诱导转化，制备出具有可控厚度的大面积-C=N-连接的二维（2D）COF薄膜。组装过程是通过PyTTA薄膜与TPA气相之间的可逆席夫碱缩聚反应实现的，这直接在生长衬底上形成了均匀的有机框架薄膜，并且在水和乙酸的辅助下，由π-π堆积相互作用驱动。通过调整其结构单元，成功合成了具有不同结构的晶圆级二维COF薄膜，表明其具有广泛的适用性。PyTTA-TPA COF薄膜的载流子迁移率可达1.89×10 cm² V⁻¹ s⁻¹。当用作析氢反应（HER）的催化剂时，与无金属的COF甚至一些金属催化剂相比，它们表现出高电催化活性。我们的结果代表了一种通用途径，可在衬底上直接构建大面积均匀的二维COF薄膜，以实现二维π共轭体系的多功能应用。
