Strengthened Delocalized Electronic Effect in Nano-Nickel@Carbon with High Pyrrolic Nitrogen for Selective Hydrogenation of Substituted Nitrobenzene Hydrogenation

Carbon-encapsulated metal (CEM) catalysts reconfigure the active site of the catalytic reaction by shifting from the conventional metal to the surface of the carbon material. Carbon-encapsulated structure has attracted wide attention in the fields of electrochemistry, thermal catalysis and photocatalysis. Herein, a nitrogen-doped carbon-encapsulated nickel catalyst was synthesized via hydrothermal synthesis, with pyrrolic N (NPyr) content accounting for 48.4% of the total nitrogen species. Experiments and density functional theory calculations reveal that the five-membered pyrrole ring shares six π electrons, and its electron cloud density on the carbon surface surpasses that of benzene or pyridine ring, promoting extensive electronic interaction between NPyrC and nickel. The interaction also extends beyond the vicinity of the doping sites and permeates throughout the entire carbon shell, thereby augmenting a greater number of potential active sites on the NC layer. This strengthened delocalized electronic effect imparts specificity in the adsorption and dissociation processes of hydrogen and p-chloronitrobenzene, leading to enhanced catalytic performance in the hydrogenation production of p-chloroaniline. The precise preparation of NPyr-doped CEM catalysts demonstrates its huge potential for industrial applications.