Covalent organic frameworks for oxygen reduction: Coupling electron, proton, and molecular transport with kinetics

Abstract

The oxygen reduction reaction (ORR) remains a central kinetic bottleneck in fuel cells. Its performance depends not only on catalyst activity, but also on electron/proton transfer, oxygen transport, and surface reaction kinetics. Because catalytic reactions and mass transport occur on different timescales, their matching is essential for efficient ORR. Covalent organic frameworks (COFs) have attracted increasing interest in ORR electrocatalysis because of their tunable structures and ordered pores. However, current studies mainly focus on material classification or activity regulation, while the relationship between transport and reaction kinetics remains insufficiently understood. To bridge this gap, this review proposes a transport‐reaction coupling framework for COF‐based ORR electrocatalysts. By comparing pyrolyzed and non‐pyrolyzed COFs, a key principle is revealed: electron, proton, and oxygen transport should be balanced with regulation of the local reaction environment. This review links molecular COF design, multiscale transport, and device performance to guide the design of COF‐based ORR electrocatalysts.