A review of recent progress in modified metal–organic frameworks as photocatalysts

It is well known that metal–organic frameworks (MOFs) have aroused the interest of many researchers in the field of photocatalysis. And MOFs and its derivatives have abundant tunable chemical components, uniformly distributed active sites, and ordered micro/mesoporous structures. So far, MOFs have rapidly burgeoned as late-model photocatalysts due to their excellent intrinsic characteristics, such as ordered porous structure and large surface area. Better yet, by adjusting the combination with complex/metal catalysts or organic metal/linker clusters, not only the reactant activation and charge separation but also the reactant or light absorption can be greatly promoted, resulting in superior photocatalytic performance. Nevertheless, the bulk MOFs as photocatalysts have a wide band gap and high electron–hole recombination, which can only capture UV light and restrict their further development. Therefore, it is necessary to develop efficient photocatalysts over MOFs and MOFs-based derivatives with visible-light-driven activity by various strategies. In this paper, the progress of various modification strategies of MOFs is reviewed, including modifying metal center or organic linker, combining with semiconductors and constructing 2D metal–organic frameworks (2D-MOFs) nanosheets, three-dimensionally ordered macro-microporous MOF (hierarchical porous MOFs). The above-mentioned modified MOFs strategy can further promote visible light response, improve the effective separation and transfer of electron holes, and has good recyclability. Furthermore, the existing challenges and the development prospects of MOFs in the field of photocatalysis were also presented.