Growth of double-wall carbon nanotubes with diameter-controlled iron oxide nanoparticles supported on MgO

Abstract

We have studied the growth of carbon nanotubes by chemical vapor deposition (CVD) on the nanoparticles of iron oxide with two different diameters, 4 and 10 nm, supported on MgO powder. Both nanoparticles catalyzed the growth of double-wall carbon nanotubes (DWNTs) together with a small amount of single-wall carbon nanotubes (SWNTs). We found that the inner- and outer-diameters of the DWNTs were modified by the initial nanoparticle size; smaller nanoparticles catalyzed the growth of the DWNTs with smaller diameters. These results suggest that the MgO support strongly influence the catalytic activity of nanoparticles by reduction of the catalytically-active size.