Visible-light Responsive Cu-MOF-NH 2 for Highly Efficient Aerobic Photocatalytic Oxidation of Benzyl Alcohol

Abstract

The current study focuses on the photocatalytic oxidation of benzyl alcohol in acetonitrile under air bubbling conditions comparing titania-based materials, Cu-MOF, and Cu-MOF-NH2 as semiconductor photocatalysts. The catalysts were characterized by XRD, N2 adsorption-desorption, FT-IR, Raman spectroscopy, and TEM. The photocatalytic benzyl alcohol conversion reached ~ 100% after exposing the four prepared catalysts to a 125W mercury lamp for up to 240 min. Benzaldehyde is formed with a moderate selectivity (after a reaction time of 60 min. ca. 30% over the titania-based catalysts 37%, 45% over Cu-MOF, and Cu-MOF-NH2, respectively). The formation of electron-hole pairs at the surface of the semiconductor nanoparticles followed by oxidation reaction was the suggested mechanism. A first-order kinetic model was observed for the photocatalytic oxidation of the investigated alcohols, and the rate constants were calculated. According to preliminary research, decorating MOF linker by amine (MOF-NH2) could improve visible-light harvesting, charge separation, and electron transport of the resulting catalyst, resulting in increased photocatalytic activity. The current work offers some direction for the development of MOF-based photocatalysts for organic synthesis.