N-doped nanocarbon embedded in hierarchically porous metal-organic frameworks for highly efficient CO2 fixation

作者：Chen, Fengfeng; Shen, Kui^*; Chen, Liyu; Li, Yingwei^*

来源：Science China Chemistry, 2022, 65(7): 1411-1419.

DOI：10.1007/s11426-022-1298-9

• metal-organic frameworks
• N-doped nanocarbons
• encapsulation
• hierarchical porosity
• CO2 fixation

The rational integration of multi-functional components with metal-organic frameworks (MOFs) to form MOF-based catalysts can often afford enhanced catalytic activity for specific reactions. Herein, we propose a novel strategy for the synthesis of hierarchically porous MOFs (e.g., MIL-101)-encapsulated N-doped nanocarbon (CN@MIL) by controlled pyrolysis of ionic liquids@MIL-101 precursors (ILs@MIL). The obtained CN@MIL composites not only possess abundant enlarged mesopores, but also show multi-active sites without the sacrifice of their structure stability. The CN@MIL can efficiently facilitate the mass transfer of substrates, exhibiting excellent catalytic performance in the synthesis of cyclic carbonates from epoxides and CO2 under mild and co-catalyst-free conditions (i.e., 90 degrees C and ambient pressure of CO2). Furthermore, the multi-active Lewis acid sites and nucleophilic sites (Br ions) as well as the strong affinity of catalysts toward CO2 also contribute to the excellent catalytic activity of the CN@MIL. This study might open a new avenue for the rational design of MOF-based composites by employing ILs@MOF as precursors for advanced heterogeneous catalysis.