ATOMIC HYDROGEN-DRIVEN SIZE CONTROL OF CATALYTIC NANOPARTICLES FOR SINGLE-WALLED CARBON NANOTUBE GROWTH

International audienceThe effects of an atomic hydrogen (Hat ) pretreatment of the catalyst layer on the low tem- perature growth of single-walled carbon nanotubes (SWCNTs) have been investigated using a modified catalytic chemical vapor deposition system. Well-defined and isolated individual Fe nanoparticles as a catalyst are successfully formed on the defects with high trapping energy which are created on the Al2O3 surface by Hat pretreatment, yielding highly dense SWCNTs. The pretreatment mechanism of Hat , compared to H2 , is also discussed. It was also found that the quality of SWCNTs can be enhanced when Hat is flowed with CH4 during nanotubes growth at low temperature. In this case, the undesired carbon products and defects on catalyst seeds and nanotube walls can be selectively removed by Hat . Therefore it is essential to use Hat in the pretreatment stage for increasing catalytic activity and to keep the size of nanoparticles in the nm range. Hat can also be employed in growth stage for enhancing SWCNTs quality and density at low temperature