Axial coordination engineering of atomic Co–N4 sites for exceptional aromatic nitroreduction

Optimizing the local environment of metal active centers bonded by nitrogen ligands (M−N 4 ) through additional axial coordination provides a promising approach to enhance the reaction kinetics of heterogeneous catalysis. However, achieving precise targeting and construction of efficient active sites remains a major challenge. In this study, under the guidance of density functional theory (DFT) calculations, we precisely position and engineer atomic Co–N 4 active sites with axial O coordination on porous carbon nanosheets (Co 1 /NOC) for boosted aromatic nitroreduction through a novel template-anchoring strategy. The resulting Co 1 /NOC catalyst exhibited unprecedented catalytic activities towards a series of functionalized nitroaromatics with a record overall turnover frequency (TOF) of 38022 h −1 under mild reaction conditions, 7.6- and 38 times higher than that of Co–N 4 sites (Co 1 /NC) and commercial Pd/C catalysts, respectively, standing ahead of the reported catalysts. Targeted DFT calculations reveal that axial oxygen coordination efficiently promotes the electronic delocalization of the Co center, which dramatically facilitates the formation and utilization of reactive H* species, enhances the selective adsorption of nitroaromatics, and accelerates the conversion of aromatic nitroreduction, eventually attaining exceptional catalytic performance. This work offers a new avenue for precisely tailoring the coordination environment of single-atom catalysts to achieve advanced catalytic performance in chemical transformations.