Post-synthetic engineering of covalent organic frameworks with thiophene and naphthalimide units for enhanced oxygen reduction electrocatalysis

Abstract

The development of efficient metal-free electrocatalysts for the oxygen reduction reaction (ORR) is essential for advancing sustainable energy technologies. In this work, we report the post-synthetic functionalization of covalent organic frameworks (COFs) with donor–acceptor (D–A) motifs incorporating thiophene and naphthalimide derivatives, yielding two novel materials. These COFs were synthesized via CuAAC click chemistry and thoroughly characterized. Electrochemical analyses revealed enhanced ORR activity in both materials, with one COF exhibiting near-ideal four-electron selectivity and remarkable stability. Density functional theory (DFT) calculations corroborated the experimental results, demonstrating that the electronic structure of COFs facilitates efficient O–O bond cleavage and electron transfer. These findings underscore the potential of rationally designed D–A COFs as high-performance, metal-free ORR electrocatalysts, contributing to the development of next-generation sustainable energy conversion technologies.