Enhanced photocatalytic activity of Fe@UiO-66 for aerobic oxidation of N-aryl tetrahydroisoquinolines

Abstract

Highly dispersed iron oxide has been rapidly and precisely loaded onto the Zr₆ nodes of a stable metal–organic framework (MOF), UiO-66, via an atomic layer deposition (ALD) process to form novel Fe–O–Zr metal cluster sites. By varying the number of ALD cycles, three Fe-decorated UiO-66 materials (denoted as Fe@UiO-66-xc, x = 1, 2, 3) were synthesized. A series of photoelectrochemical measurements, including UV-vis diffuse reflectance spectroscopy, state photoluminescence spectroscopy, and transient photocurrent response, indicate that Fe@UiO-66-1c prepared by a single deposition cycle exhibits improved visible-light absorption ability and enhanced photo-generated charge carrier separation efficiency due to metal-to-metal charge transfer. Moreover, Fe@UiO-66-1c shows excellent photocatalytic activity for aerobic oxidation of N-aryl tetrahydroisoquinolines. This material also exhibits good stability and is capable of cycling the reaction six times and maintaining the crystal structure with a low leaching rate of iron ions. The study explores the application of the atomic layer deposition process in the preparation of advanced photocatalytic materials.