Metal-organic framework composites for photocatalysis

In the past decades, metal-organic frameworks (MOFs) have gained great attention as a promising candidate in photocatalytic applications, leveraging their tunable pores, well-defined structures, ease of functionalization and inherent semiconductor properties. Nevertheless, owing to their poor light-harvesting capability and suboptimal electron-hole separation efficiency, their catalytic performances have yet to meet the prerequisites for industrial deployment. To address this issue, researchers started to incorporate guest substances into MOFs, thereby integrating multiple functions or advantages to form MOF composites. Through the construction of active interfaces and the introduction of functional units, the light absorption capacity, charge separation and the reaction activity are pointedly optimized, thus enhancing the overall photocatalytic performances. Moreover, the composites exhibit various active sites with well-defined coordination configuration, facilitating the study of the photocatalytic mechanism. Herein, this review provides an overview of commonly used MOF composites in photocatalysis, including metal nanoparticles/MOFs, semiconductors/MOFs, carbon materials/MOFs, aerogels/MOFs, polymers/MOFs, reticular frameworks/MOFs, and MOF composites with others, summarizes their synthesis strategies, and presents their latest applications in photocatalytic water splitting, CO₂ reduction, N₂ reduction and organic reactions. We hope that this review will highlight the advantages and challenges of MOF composites in photocatalysis and inspire the development of more efficient and widely applicable novel MOF composite photocatalysts.