Photocatalytic Multielectron Reduction of Nitroarenes to Anilines by Utilizing an Electron-Storable Polyoxometalate-Based Metal–Organic Framework

Abstract

A powerful approach to generate photocatalysts for the highly selective reduction of nitrobenzene using light as the driving force is a combination of photosensitizers and electron-storable components in a cooperative photocatalysis fashion. Herein, a new precious metal-free photocatalyst, <b>{ZnW-TPT}</b>, was prepared by incorporating a Zn-substituted monovacant Keggin polyanion [SiZnW₁₁O₃₉]^6- and a photoactive organic bridging link 2,4,6-tri(4-pyridyl)-1,3,5-triazine (TPT) into a framework. In this structure, the direct coordination bond between [SiZnW₁₁O₃₉]^6- and the TPT ligand and the π-π interactions between TPT molecules help separate and migrate photogenerated carriers, which improves the photocatalytic activity of <b>{ZnW-TPT}</b>. The photoelectrochemical properties of <b>{ZnW-TPT}</b> were well studied by solid UV-vis absorption, fluorescence, transient photocurrent response, and electrochemical impedance spectroscopy tests. <b>{ZnW-TPT}</b> efficiently converts using hydrazine hydrate with 99% conversion and 99% selectivity for anilines under mild conditions.