Tuning electron delocalization and surface area in COFs derived N, B co-doped carbon materials for efficient selective hydrogenation of nitroarenes

Metal-free carbon catalysts with excellent conduction performance have drawn much research attention in reduction reactions. Herein, a N, B co-doped carbon catalyst with high pyrrolic N proportion (35.75%) and excellent surface area (1409 m²/g) was successfully prepared via carbonizing covalent organic framework materials (COFs) containing N and B atoms assisted by ZnCl₂ molten salt. The presence of ZnCl₂ maintains the micropore structure of COFs to provide high specific surface areas and abundant lattice defects for carbon materials. In addition, electron-withdrawing B heteroatom further facilitates the formation of pyrrolic N at defect sites by modifying the electronic structure of carbon network. The tuning of surface areas and active N species in carbon catalysts successfully improve the selective hydrogenation of nitrobenzene to aniline. The optimized carbon material exhibits excellent nitrobenzene conversion (99.9%) and aniline selectivity (>99%) within 15 min, as well as excellent substrate suitability. This work provides a certain guiding for the design and application of metal-free catalysis.