In situ XAFS study on chemical states of Co and Ir nanoparticles under conventional growth condition of single-walled carbon nanotube via alcohol catalytic chemical vapor deposition

Abstract

In situ X-ray absorption fine structure (XAFS) analysis was performed on Co and Ir catalysts during single-walled carbon nanotube (SWCNT) growth via alcohol catalytic chemical vapor deposition (Ar/H2 carrier gas). The Co catalysts were partially reduced during heating to 800 °C, and partially carbonized during SWCNT growth upon ethanol addition. The Ir catalysts were reduced during heating and became metallic at 900 °C; the Ir catalysts remained metallic during SWCNT growth upon ethanol addition. The chemical states of the catalyst particles varied with the metal properties during SWCNT growth; thus supporting the growth model proposed using atomistic computer simulations.