Thiazolium‐Linked Crystalline Porous Covalent Organic Frameworks for Mixed Electronic‐Ionic Transport

Abstract Developing efficiently mixed electronic‐ionic (MEI) conductive microcosmic pathways within a single functional material is essential yet challenging for electronic devices. Covalent organic frameworks (COFs) feature pre‐designed functionalities and uniform pores, making them highly desirable platforms for transporting electrons and ions. However, for MEI conductive COFs, achieving high crystallinity when incorporating high‐density ionic groups within the extensively π‐electron delocalized skeletons remain a challenge due to intermolecular interactions. Herein, we reported a “pre‐polymerization followed by self‐ionization” approach to synthesize new thiazolium‐linked COFs (MEICOFs, M═Cu, Co, Fe), where the ionic groups synthesized following the connection of building blocks. MEICOFs demonstrated broad ultraviolet‐visible‐near‐infrared absorption bands and narrow bandgaps. As a proof of concept, the mixed electronic and hydroxide ionic conductivity of CuEICOF was determined to be 55.2 and 0.01 S m −1 , respectively. Moreover, MEICOFs film could directly catalyze the oxygen reduction reaction without additional conductive agent and the rotation of the electrode.