Enhancement of visible-light-driven photocatalytic oxidative amine coupling through light-induced carrier spatial separation

Abstract

Efficient charge separation and utilization are critical factors in photocatalysis, especially for photocatalytic oxidative amine coupling, which utilizes both electrons and holes to obtain reactive oxygen species. Herein, a Pt@UiO-66-NH₂-OH@Cu₂O composite, featuring spatial separation of reduced Pt nanoparticles (NPs) and oxidized Cu₂O NPs with defect-engineered UiO-66-NH₂-OH, is reported for enhancing visible-light-driven photocatalytic oxidation of amines. The Pt NPs embedded in the MOF pores act as electron collectors, while the Cu₂O NPs covering the surface of the MOF serve as hole collectors. This spatial separation effectively directs the electron and hole flow, reduces electron–hole recombination and enhances the charge separation efficiency. Besides, the highly porous structure of Pt@UiO-66-NH₂-OH@Cu₂O exhibits confined cavities and high surface area and can reduce the kinetic resistance to substrate and product diffusion. Therefore, Pt@UiO-66-NH₂-OH@Cu₂O exhibits excellent photocatalytic activity for the oxidation of benzylamine to obtain N-benzyl-1-phenylmethanimine as the solo product and achieve a high conversion rate of 99% under low-energy LED light.