Heterogeneous Nanosized Metal (Metallic Compound)@Metal-Organic Framework Composites: Recent Advances in the Preparation and Applications

Metal-organic framework (MOF) composites based on MOFs-wrapped metals or metallic compounds (denoted as M/MC@MOFs) are an important class of materials that integrate M/MCs and MOFs. MOFs can fix and confine M/MCs to regulate their size, prevent uncontrollable aggregation, and enhance the exposure and ordered arrangement of active sites. In turn, M/MCs support the MOFs to enhance their stability and realize more targeted properties. In this review, the features and application scope of different M/MC@MOF synthesis methods are explored, considering the influential factors and regulation modes of the M/MC-MOFs integration. Additionally, the performances of the M/MC@MOF composites are comprehensively discussed, and the underlying mechanisms are clarified. The performance of M/MC@MOFs is dependent on the orderly synergy between the MOFs and M/MCs. MOFs can sieve and transfer specific molecules to the M/MC surface, whereas the robust interface provides new charge/energy-transfer pathways, which enhance the activity and selectivity of the composites for diverse molecules. Furthermore, the challenges facing this field are analyzed, and the recommendations for advancing the development of M/MC@MOF composites are presented.