Modulating the catalytic behavior of non-noble metal nanoparticles by inter-particle interaction for chemoselective hydrogenation of nitroarenes into corresponding azoxy or azo compounds

Aromatic azoxy compounds have wide applications and they can be prepared by stoichiometric or catalytic reactions with H2O2 or N2H4 starting from anilines or nitroarenes. In this work, we will present the direct chemoselective hydrogenation of nitroarenes with H2 to give aromatic azoxy compounds under base-free mild conditions, with a bifunctional catalytic system formed by Ni nanoparticles covered by a few layers of carbon ([email protected] NPs) and CeO2 nanoparticles. The catalytic performance of [email protected]2 catalyst surpasses the state-of-art Au/CeO2 catalyst for the direct production of azoxybenzene from nitrobenzene. By means of kinetic and spectroscopic results, a bifunctional mechanism is proposed in which, the hydrogenation of nitrobenzene can be stopped at the formation of azoxybenzene with >95% conversion and >93% selectivity, or can be further driven to the formation of azobenzene with >85% selectivity. By making a bifunctional catalyst with a non-noble metal, one can achieve chemoselective hydrogenation of nitroarenes not only to anilines, but also to corresponding azoxy and azo compounds.