Nanocomposites of Platinum/Metal-Organic Frameworks Coated with Metal-Organic Frameworks with Remarkably Enhanced Chemoselectivity for Cinnamaldehyde Hydrogenation

The encapsulation of metal nanoparticles (MNPs) within metal-organic frameworks (MOFs) to form core-shell structural nanocomposites is one of the most promising methods to enhance the durability and selectivity of MOF-supported metal catalysts. However, it is still a challenge to fully encapsulate tiny MNPs inside MOFs. Herein, we report a facile and general strategy to coat MOFs on the surface of Pt/MOFs by direct homoepitaxial growth. The obtained Pt/MOFs@MOFs nanocomposites retained the intrinsic properties (e.g., crystalline structure, pore texture, and surface area) of Pt/MOFs. Strikingly, the MOF-coated materials exhibited a significantly enhanced chemoselectivity compared to the uncoated materials, for example, in the hydrogenation of cinnamaldehyde, the selectivity to cinnamyl alcohol through C=O hydrogenation was improved from 55 to 96% at complete conversions of cinnamaldehyde. Moreover, Pt/MOFs@MOFs can be recycled without any remarkable loss in both activity and selectivity. The enhanced catalytic selectivity and stability of MNPs/MOFs could be related to the synergetic effects of the electron donation and nanoconfinement offered by the surrounding MOF networks.