It was recalled that, in the chemical vapor deposition process for C nanotube growth using catalytic particles, many C atoms as well as H atoms co-existed on the surfaces of catalysts. Their mutual interactions could change the adsorption and diffusion of C atoms. In order to investigate the effect of H upon C diffusion on the Ni(111) surface, pseudopotential density-functional calculations were performed. The diffusion barriers to CHx (x = 1, 2, 3) on Ni(111) were obtained and were compared with that of a single C atom. The diffusion barrier decreased in the presence of attached H atoms, which implied that adsorbates with more H were likely to diffuse more easily.

Effect of Hydrogen on Carbon Diffusion on Ni(111). Y.H.Shin, S.Hong: Japanese Journal of Applied Physics, 2004, 43[2], 773-4