Preparation of Monodispersed Fe−Mo Nanoparticles as the Catalyst for CVD Synthesis of Carbon Nanotubes

Uniform iron−molybdenum nanoparticles were prepared by thermal decomposition of metal carbonyl complexes using a mixture of long-chain carboxylic acid and long-chain amine as protective agents. The sizes of the nanoparticles can be systematically varied from 3 to 14 nm by changing the experimental conditions. High-resolution TEM images and EDX data show that the prepared nanoparticles are highly crystalline iron nanoparticles containing ≈4% molybdenum. The effects of the concentration, reaction time, the ratio of metal carbonyl complexes versus protective agents, and the ratio of acid/amine of the protective agents on the sizes of the produced nanoparticles were systematically studied. The prepared nanoparticles were used as catalysts for single-walled carbon nanotube growth and the results indicate that there is an upper limit for the size of the catalyst particles to nucleate single-walled carbon nanotubes.