Abstract
The production of functionalized anilines by chemoselective hydrogenation of nitroarenes occupies an important position in the chemical industries. Recently, cobalt and nitrogen codoped carbon (Co-N-C) catalysts have been reported to show outstanding catalytic performance in this process, whereas the nature of their active sites is still at the center of intense debate. In this paper, based on the well-controlled experiments on four types of typical Co-N-C materials derived from different methodologies, several unusual generalities in the hydrogenation of nitroarenes are clearly revealed, including protic-solvent dependence, antipoisoning, acid resistance, and reversible deactivation. Further investigations indicate that the single-atom species Co-N-x are the main active sites of the Co-N-C catalysts in this chemoselective hydrogenation process. The present work sheds light on the mechanism study on the metal-N-C catalysts and further contributes to the rational design of the high-performance single-atom catalysts.