▎ 摘　　要

Proper size, density, and activity of catalyst nanoparticles are the key prerequisites for the growth of vertically aligned carbon nanotubes (or forests), which are expected to have unprecedented applications. The main challenge during growth is to create a high density of catalyst particles that remain catalytically active, and with a size distribution feasible for nucleation in the course of the nanotube growth. Here, we show that Fe dusters supported on graphene-covered silicon substrates enable forest growth with heights up to twice as compared to bare silicon along with an increase in tube density up to 30%. Detailed comparative analysis of nanotube growth kinetics, catalyst particle size distribution, and Fe nanoparticle phases on graphene-covered and bare substrates strongly suggests that graphene enhances the catalytic activity of Fe nanoparticles.