Nitrogen-doped carbon nanotubes as a highly active metal-free catalyst for nitrobenzene hydrogenation

Abstract A series of metal-free N-doped carbon nanotubes (CNTs) are fabricated using an in-situ synthesis and post nitridation treatment. N-doped carbon nanotubes with various defects, nitrogen contents, and nitrogen species are employed as the catalysts for nitrobenzene hydrogenation. The potential active sites of N-doped carbon nanotubes are explored in terms of catalytic performance in nitrobenzene hydrogenation as well as DFT calculations of hydrogen adsorption on carbon nanotubes and nitrogen species. Active and selective hydrogenation of nitrobenzene is achieved over N-doped carbon nanotubes prepared by post nitridation. Pyrrolic-N in the N-doped carbon nanotubes is found to play an active site for nitrobenzene hydrogenation, which is greatly in favor of the chemisorption and dissociation of hydrogen molecules. N-doped carbon nanotubes with pyrrolic-N show an encouraging catalytic hydrogenation activity in nitrobenzene reduction. These findings provide a promising route for the rational design of the metal-free hydrogenation catalysts and the development of carbon nanotube-based materials.