Fabrication of NH2-MIL-125 nanocrystals for high performance photocatalytic oxidation

Abstract

Developing a facile route for improving the photocatalytic performances of metal–organic frameworks is of great importance. Herein, we demonstrate for the first time that downsizing NH₂-MIL-125 crystals to the nanometer scale can greatly improve their activity for the photocatalytic benzylamine oxidation reaction. Under mild conditions, the conversion of benzylamine into N-benzylbenzaldimine reaches 98.5% in 9 h with a turnover frequency (TOF) value of 1063 μmol g⁻¹ h⁻¹ as catalyzed by NH₂-MIL-125 nanocrystals, much superior to NH₂-MIL-125 microcrystals (conversion 55.9% and TOF 570 μmol g⁻¹ h⁻¹, respectively). The as-synthesized NH₂-MIL-125 nanocrystals have a small crystal size, abundant oxygen vacancies, enhanced light absorption ability, strong oxygen reduction capacity, strengthened separation capability and transfer efficiency of photoexcited charges, conferring them high photocatalytic performance for the benzylamine oxidation reaction.