Synthesis of sp2 Carbon‐Conjugated Covalent Organic Framework Thin‐Films via Copper‐Surface‐Mediated Knoevenagel Polycondensation

sp2 carbon‐conjugated covalent organic framework (sp2c‐COF) featured with high π‐conjugation, high chemical stabilities, and designable chemical structures, are thus promising for applications including adsorption and separation, optoelectronic devices, and catalysis. For the most of these applications, large‐area and continuous films are required. However, due to the needs of harsh conditions in the formation of CC bonds, classical interfacial methodologies are challenged in the synthesis of sp2c‐COFs films. Herein, a novel and robust interfacial method namely copper‐surface‐mediated Knoevenagel polycondensation (Cu‐SMKP), is shown for scalable synthesis of sp2c‐COF films on various Cu substrates. Using this approach, large‐area and continuous sp2c‐COF films could be prepared on various complicated Cu surfaces with thickness from tens to hundreds of nanometers. The resultant sp2c‐COF films on Cu substrate could be used directly as functional electrode for extraction of uranium from spiked seawater, which gives an exceptionally uptake capacity of 2475 mg g−1. These results delineate significant synthetic advances in sp2c‐COF films and implemented them as functional electrodes for uranyl capture. Nowadays, the sp2c‐COFs are mostly prepared by the form of powders rather than thin film, which greatly limit their applications. In this work, the smooth and continuous sp2c‐COFs film is successfully synthesized by copper‐surface‐mediated Knoevenagel polycondensation. The as‐prepared sp2c‐COFs film can be directly used to electrochemical seawater uranium extraction and exhibit excellent uranium extraction capacity.