Electrochemically Controlled Deposition of Low‐Crystalline Covalent Organic Frameworks on Nanocarbon Electrode Toward Metal‐Free Oxygen Reduction Electrocatalyst

Abstract Morphology‐controlled synthesis of covalent organic frameworks (COFs) offers significant potential for electrochemical applications. However, controlling the deposition of nanometer‐scale COFs on carbon supports remains challenging due to the need for a slow COF generation rate and the dispersion of carbon supports in liquid‐phase synthesis. In this study, nanometer‐scale COF/carbon composites are fabricated using electrochemically generated acid (EGA) to assist in the formation of imine‐type COFs, which are then deposited onto pre‐cast nanocarbon supports on an electrode. A monomer combination of tri(4‐aminophenyl)‐1,3,5‐triazine and 2,5‐dimethoxybenzene‐1,4‐dicarboxaldehyde is utilized due to their suitable oxidation potentials, with 1,2‐diphenylhydrazine serving as the EGA source. Through proton generation driven by electrolysis conditions, controlled COF formation is achieved at the single nanometer scale, ranging from 6 to 30 nm, on various nanocarbon supports. The COF/carbon electrode is evaluated as an oxygen reduction reaction (ORR) electrocatalyst, demonstrating superior performance compared to other COF‐based electrode materials containing the 1,3,5‐triazine moiety. The findings experimentally validate the efficacy of the EGA‐assisted COF deposition method for nanostructure construction and its ability to enhance the properties of COF‐based electrodes through morphology tuning.