Shedding light on unprecedented spatial confinement of metal clusters by metal/covalent organic frameworks for photocatalysis

Atomically precise metal clusters have gained widespread attention in the rational design of high-performance photocatalysts due to their distinctive characteristics, such as tunable size, elemental composition, and surface chemistry. A promising research avenue involves the anchoring of metal clusters within the porous materials, including metal–organic frameworks (MOFs), covalent organic frameworks (COFs), etc., to construct hybrid composites. Considering the rapid development of metal cluster-anchored porous frameworks as efficient photocatalysts, a comprehensive review is essential to further advance this domain, which begins by outlining the fundamental mechanisms and photocatalytic properties of the selected porous frameworks. We emphasize the synthesis methods used for fabricating cluster-anchored porous frameworks. Subsequently, a detailed classification of metal cluster-anchored porous M/COF composites and the mechanisms responsible for the observed improvements in photocatalytic performance is presented. Finally, this review addresses existing challenges and outlines future research directions, aiming to inspire the development of intelligent cluster@M/COF composites with significantly improved photocatalytic results.