Donor-Acceptor Covalent Organic Frameworks Propel Oxygen Reduction Reaction with Push-Pull Dynamics

Abstract

Structurally tunable covalent organic frameworks (COFs) have emerged as promising electrocatalysts for the oxygen reduction reaction (ORR) due to their highly controllable functionality and porous channels. We have constructed imine-linked COFs with various functional moieties to regulate push-pull interactions, enhancing electrocatalytic ORR performance. Unlike most studies that incorporate metals or conductive supports, or employ additional carbonization procedures to improve conductivity and catalytic activity, we have fine-tuned the electronic properties of the active imine units to create a self-sufficient COF material for effective ORR performance. A comprehensive study of the structure-function relationship at the active site reveals that the imine linkage engages oxygen molecules in a five-membered ring through push-pull interactions. The ORR mechanism is elucidated using in-situ Fourier Transform Infrared (FT-IR) spectroscopy and density functional theory (DFT) calculations, providing robust support for the proposed push-pull interaction mechanism.