Three-dimensional porphyrin-based covalent organic frameworks as bifunctional electrocatalysts for oxygen reduction and evolution reactions

Abstract

The development of covalent organic frameworks (COFs) as bifunctional electrocatalysts for the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER), coupled with precise control over their active sites, is critical for advancing fuel cells and metal–air batteries. In this work, we present a series of three-dimensional (3D) COFs constructed from two strategically designed metal-porphyrin monomers. Among these, SUZ-101-Co stands out due to its high density of well-defined Co–N₄ active sites, making it an outstanding bifunctional electrocatalyst. SUZ-101-Co exhibits an overpotential of only 240 mV at 10 mA cm⁻² for the OER and achieves a half-wave potential of 0.78 V for the ORR, showcasing its superior catalytic performance. Comprehensive experimental analyses and theoretical simulations attribute this remarkable activity to the abundance and accessibility of Co–N₄ sites. This study not only underscores the potential of 3D COFs in electrocatalysis but also introduces a novel approach for designing energy conversion materials.