Visible-Light Responsive Cu–MOF–NH2 for Highly Efficient Aerobic Photocatalytic Oxidation of Benzyl Alcohol

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 isotherm, FTIR, Raman spectroscopy, and TEM. The photocatalytic benzyl alcohol conversion reached ~100% after exposing the four prepared catalysts to a 125 W mercury lamp for up to 240 min. Benzaldehyde is formed with a moderate selectivity (after a reaction time of 60 min. ca. 30, 37 and 45% over the titania-based catalysts, 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. The initial rate of benzyl alcohol oxidation was 4.6 and 4.7 mmol g–1 min–1 for titania-based materials. Cu–MOF and Cu–MOF–NH2 showed a higher initial rate of reaction of 6.1 and 9.1 mmol g–1 min–1. According to preliminary research, decorating MOF linker by amine (MOF–NH2) could improve visible-light harvesting, charge separation, and electron transport of the catalyst, resulting in increased photocatalytic activity. The current work offers some directions for the development of MOF-based photocatalysts for organic synthesis.