A Nanocrystalline POM@MOFs Catalyst for the Degradation of Phenol: Effective Cooperative Catalysis by Metal Nodes and POM Guests.

Crystalline POM@MOFs hybrids are very promising for catalysis, due to catalytically active polyoxometalates (POMs) dispersed at the molecular level, and enhanced stability of both POMs and metal-organic frameworks (MOFs). Herein, PW12 was encapsulated into MOF HKUST-1 through a facile liquid-assisted grinding method, and the obtained [Cu2 (BTC)4/3 (H2 O)2 ]6 [HPW12 O40 ] (BTC=1,2,3-benzenetricarboxylic acid) nanocrystals (NENU-3N) were applied as catalysts in the degradation of phenol. It is the first time that liquid-assisted grinding was applied in the preparation of nanocrystalline POM@MOFs hybrids. The NENU-3N nanocrystals catalyzed the degradation of phenol on the basis of both MOF and POM catalytic activities, representing the first example of POM@MOFs catalyst boosting catalytic oxidation reaction with double actives sites. Strikingly, up to 97 % conversion and 88 % mineralization have successfully realized by perfect cooperative catalysis between POMs and CuII nodes in MOFs at 35 °C. Moreover, comparative experiments suggest that the reduced size of NENU-3N catalyst is beneficial for improving its catalytic performance. Finally, the nanocrystalline NENU-3N catalyst possesses high stability, which can be easily recovered and reused 5 times without loss of catalytic activity.