PDI bridged MIL-125(Ti)-NH2 heterojunction with frustrated Lewis pairs: A promising photocatalyst for Cr(VI) reduction and antibacterial application

Inspired by the concept of frustrated Lewis pairs (FLPs) from homogeneous catalysis, an organic supramolecular bridged metal-organic frameworks (MOFs) heterojunction, i.e., a perylene-3,4,9,10-tetracarboxylic diimide@MIL-125(Ti)-NH2 (denoted PDI@MTi) composite is successfully fabricated via a two-step synthesis method. Experimental characterisations and theoretical calculations reveal that in the obtained TiO5 x-ligand-PDI FLPs, the unsaturated Ti-O clusters function as a Lewis acid to accept photogenerated electrons, and the PDI sites act as a Lewis base to capture photogenerated holes. With the unique structure characteristics, the PDI@MTi shows excellent photocatalytic activity toward the disinfection of Staphylococcus aureus and Cr(VI) reduction, with 1.0- and 10.3-fold enhancements, respectively, compared with unadorned MTi. The synergic effects of the micro polarisation field, multiple active sites, and a C-N bonded interface contributed to photoactivity enhancement. This work demonstrates the potential of using MTi as a platform for constructing FLPs-containing heterogeneous photocatalysts and provides new strategies to control carrier separation.

Automated summary

Inspired by FLPs concept, an organic supramolecular bridged MOFs heterojunction was fabricated, showing enhanced photocatalytic activity for disinfection and Cr(VI) reduction.