Confining atomically precise nanoclusters in metal-organic frameworks for advanced catalysis

Combining metal nanoclusters (NCs) with functional supports provides excellent potential for exploring the host-guest interactions and rational design of highly active NC-based catalysts, while metal-organic frameworks (MOFs) have recently shown unprecedented prospects for NC immobilization. Unlike other common supports, MOFs possess accurate and tunable framework structures that can be easily modified with various functional groups and serve as the perfect platform for optimizing the activity of immobilized NCs. With a further understanding of the NC-MOF interactions, the NC/MOF nanocomposites can be precisely designed to meet the specific requirements for efficient catalysis. In this review, the synthesis strategies of NC/MOF nanocomposites are first introduced. We have mainly focused on summarizing the enhanced activity of NC/MOF nanocomposites, along with the specific reasons for such increased activity. The improved catalytic activity of composites has been classified and discussed in detail (MOF-endowed protection and selectivity, MOF-assisted ligand engineering, MOF-promoted reactant enrichment, MOF-involved synergistic effect, and MOF-regulated microenvironment). Finally, the barriers and the possible future perspectives in this field are proposed, which are anticipated to provide some new insights into designing smart NC/MOF nanocomposites with elevated catalytic efficiency.