Research progress in photocatalytic carbon dioxide reduction performance of covalent organic frameworks

<p indent="0mm">COFs are attracting more and more interest in photocatalytic CO₂ reduction because of their semiconductor properties, tunable structure, and abundant metal coordination sites. In this review, the progress of COF-based photocatalytic systems for CO₂ reduction is summarized from the aspects of functional structures and active sites. First, we introduce metal-free intrinsic COFs, which show relatively low activity due to the lack of active sites. Introducing metal active sites or constructing heterojunctions in COFs is an effective strategy to improve photocatalytic efficiency. We discuss single metal COFs and multi-metal COFs materials from the advantages and disadvantages of the construction of metal active sites in COFs. Meanwhile, three type of commonly used heterojunctions are clarified. The importance of the construction of heterojunctions in improving the performance of COFs photocatalysts and the existing problems are described. Finally, we summarize the challenges and opportunities of COFs for photocatalytic CO₂ reduction from synthesis, structural design, mechanism, and environmental and economic benefits.