Plasmon-enhanced and controllable synthesis of azobenzene and hydrazobenzene using Au/TiO2 composite

Abstract The selective reduction of nitroaromatics has long been the focus of fundamental and practical interest. The challenging issue lies in how to finely control the product selectivity. Herein, we report a light-assisted thermocatalytical process to convert nitrobenzene into azobenzene and hydrazobenzene with high selectivity and high yields by simply controlling the reaction time. The light-enhanced efficiency of Au/TiO2 catalyst is up to 14.8% at 90 °C due to the localized surface plasmon resonance (LSPR) effect of Au nanoparticles. Moreover, the hydrogen-delivery rate here is much faster than that of current reported systems. The reaction mechanism was also investigated by EPR technique, where Au–H intermediate species is found to account for the high efficiency in this reduction process. The favorable results demonstrated that plasmon-enhanced catalytic reaction might be more attractive and applicable in industrial organic synthesis.