Cocatalyst Engineering in Covalent Organic Frameworks Boosts Photocatalysis

ABSTRACT As emerging crystalline porous organic polymers, covalent organic frameworks (COFs) have shown great potential in photocatalysis due to their designable structures, high surface areas, ordered pores, excellent stability, and tunable optoelectronic properties. However, COFs typically suffer from rapid charge recombination, sluggish surface reaction kinetics, and insufficient reactant activation, which severely limit their photocatalytic efficiency. To overcome these challenges, introducing cocatalysts into COF matrices has proven effective. Cocatalysts act as charge‐trapping centers to promote electron–hole separation and provide highly active catalytic sites to lower reaction barriers, thereby enhancing the overall quantum efficiency and reaction rate. This review systematically summarizes recent progress on various cocatalysts in COF photocatalytic systems, focusing on four types: noble metal, non‐precious metal, molecular, and single‐atom cocatalyst. We further discuss how cocatalyst engineering optimizes photocatalytic performance. Finally, we summarize the current challenges faced by COF photocatalysts and outline future directions, aiming to provide theoretical guidance for the design and development of more efficient and stable COF‐based composite photocatalysts.