Design of Covalent Organic Frameworks Mimicking Cytochrome c Oxidase for Enhanced Electrocatalytic Oxygen Reduction

Abstract

Designing an artificial enzyme that mimics the catalytic activity and environment of natural enzymes is highly desirable but remains challenging. Drawing inspiration from cytochrome c oxidases (CcO), which can fully reduce oxygen to water via a four-electron pathway, a bionic covalent organic framework (COF) is designed that uses iron phthalocyanine (FePc) – a compound with a similar structure to CcO – as a building block. Using a post-modification method, a bionic channel environment containing quaternary ammonium ions is created. Featuring abundant and accessible Fe active sites, excellent durability and conductivity, and effective transfer channels, the resulting quaternary amination COF demonstrated competitive electrocatalytic performance in oxygen reduction reaction (ORR), achieving a half-wave potential (E1/2) of 0.94 V (vs RHE) and a power density of 211.5 mW cm−2 in a zinc-air battery (ZAB) device. This work expanded the variety of dioxin-linked COFs and provided a platform for the development of customized bionic electrocatalysts for oxygen electrocatalysis.