Synergism of Co and Mo in the catalytic production of single-wall carbon nanotubes by decomposition of CO

• Published in: Carbon (New York) Vol. 39; no. 4; pp. 547 - 558
• Main Authors: Alvarez, W.E., Kitiyanan, B., Borgna, A., Resasco, D.E.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.01.2001; Elsevier Science
• Subjects: A. Carbon nanotubes; B. Chemical vapor deposition; C. Thermal analysis; CARBON MONOXIDE; Catalysis; CATALYTIC EFFECTS; Catalytic reactions; Chemistry; Colloidal state and disperse state; DECOMPOSITION; Exact sciences and technology; FABRICATION; General and physical chemistry; General, apparatus, technics of preparation; MATERIALS SCIENCE; MOLYBDENUM; NANOTUBES; NATIONAL SYNCHROTRON LIGHT SOURCE; SYNERGISM; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; Transmission electron microscopy (TEM); XANES/EXAFS; B. Chemical vapor deposition; C. Thermal analysis; XANES/EXAFS; Transmission electron microscopy (TEM); A. Carbon nanotubes; Transmission electron microscopy; XANES spectrometry; Preparation; Nanotube; Raman spectrometry; Carbon monoxide; Carbon; Chemical vapor deposition; Catalyst; EXAFS spectrometry
• ISSN: 0008-6223; 1873-3891
• DOI: 10.1016/S0008-6223(00)00173-1

The catalyst composition and operating conditions for the synthesis of single-wall carbon nanotubes (SWNT) from CO decomposition have been systematically varied in order to maximize the selectivity towards SWNT. A simple quantification method based on the standard Temperature Programmed Oxidation (TPO) technique has allowed us to determine the distribution of the different forms of carbonaceous deposits present on the catalysts after the CO decomposition reaction. A synergistic effect between Co and Mo has been observed. When both metals are simultaneously present, particularly when Mo is in excess, the catalyst is very effective. However, when they are separated they are either inactive (Mo alone) or unselective (Co alone). To understand this synergistic effect, X-ray absorption spectroscopy (EXAFS and XANES) has been used to characterize the state of Co and Mo on the catalysts before and after the production of SWNT.