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

Abstract

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.