Postsynthetic Modification of Covalent Organic Frameworks for Photocatalytic CO ₂ Reduction

Photocatalytic CO 2 reduction reaction (CO 2 RR) is a crucial solar‐driven technology for achieving carbon neutrality, as it enables the conversion of CO 2 into value‐added fuels and chemicals. Covalent organic frameworks (COFs) have emerged as promising photocatalysts for CO 2 RR due to their molecularly designable backbones and well‐defined porous architectures. However, their catalytic efficiency is severely limited by rapid photogenerated charge recombination and insufficient active sites. Postsynthetic modification (PSM, Scheme 1) has been recognized as a powerful strategy to overcome these inherent drawbacks, as it allows precise tailoring COF functionalities while preserving the structural integrity of crystalline framework. This review systematically summarizes recent advances in PSM strategies for CO 2 RR, focusing on three key approaches: covalent bond transformation, construction of metallic microenvironment, and linker functionalization. Further discussion centers on major challenges: ensuring long‐term stability, reconciling the trade‐offs among efficiency, selectivity, and cost, achieving scalability, and unraveling the underlying reaction mechanisms. Future perspectives are directed toward designing robust COF backbones, constructing low‐cost systems, developing environmentally friendly scalable fabrication processes, and enhancing performance under low CO 2 concentrations with the aid of advanced characterization and artificial intelligence modeling. This review provides insights and valuable understanding for rational design and synthesis of high‐performance COF‐based photocatalyst for efficient CO 2 RR.