Large-scale preparation of B/N co-doped graphene-like carbon as an efficient metal-free catalyst for the reduction of nitroarenes

摘要

Boron and nitrogen co-doped graphene-like carbon (BNG) is a metal-free catalyst that has been synthesized by combining ball-milling with thermal treatment. Firstly, the edge-selectively-functionalized graphene nanoplatelets (EFGnPs) were prepared by ball milling of the pristine graphite, which can facilitate boron incorporation. BNG catalysts with a high content of boron and nitrogen can then be obtained by pyrolysis of a mixture of EFGnPs and boric acid. We found that the reduction of nitroarenes can be catalyzed using a low BNG loading and a small amount of N2H4 in ethanol to form aminoarenes in high yields. The type of boron species in the BNG catalyst has an important effect on the reduction reaction. Furthermore, the catalyst containing the most B/N shows the highest catalytic activity during the reduction of nitroarenes, indicating that the doped B/N within the BNG is a key active site in impelling this reaction. Moreover, the BNG catalyst can be used six times, and no dehalogenation phenomenon occurs during the reduction process for halogen-substituted nitroarenes in contrast to the case when conventional metal catalysts are used.