ZIF-8@ZIF-67 Derived Co/NPHC Catalysts for Efficient and Selective Hydrogenation of Nitroarenes

Constructing nitrogen-doped porous hollow carbon with loading of non-precious metal for highly efficient hydrogenation of nitroarenes is desirable but challenging. Herein we report a facile self-sacrificing template strategy to prepare Co embedded in nitrogen-doped porous hollow carbon (Co/NPHC) from pyrolysis of well-designed core–shell ZIF-8@ZIF-67. The pyrolysis of ZIF-8@ZIF-67 at 900 °C endowed as-resultant Co/NPHC-900 with high specific surface area, hollow structure and hierarchical mesopore, favoring the dispersion of Co species and then generating abundant Co-Nx active sites, also promoting mass transport of substrates and products. As a result, the Co/NPHC-900 catalyst showed excellent activity and extraordinary selectivity in the hydrogenation of nitrobenzene, which far surpassed Co/NPC-900 and ZnCo/NPC-900 catalysts derived from sole ZIF-67 and ZnCo-BMZIF, respectively. It also had a broad substrate scope and good reusability. Furthermore, characterization and control experiments showed that Co single atoms should be catalytic active sites rather than Co nanoparticles for Co/NPHC-900. Our work provides a good candidate for the replacement of precious metal catalysts for selective hydrogenations as well as contributes to the rational design of high-performance single-atom catalysts.Graphical abstract