Two different floating catalyst synthesis methods were used to investigate the effect of CO2 and H2O vapor on the growth of single‐walled carbon nanotubes (CNTs). As a carbon source and catalyst material, carbon monoxide and iron nanoparticles were used. The catalyst particles were prepared by evaporation from a resistively heated iron wire (hot wire generator) and by thermal decomposition of ferrocene vapor. The essential role of CO2 and H2O in the CNT formation was demonstrated. The addition of small amounts of CO2 and H2O vapor in the reactor resulted in an increase in CNT length. Also, the CO2 introduction was found to decrease the minimum temperature of the CNT synthesis from 890 °C to below 600 °C.
- single-walled carbon nanotubes