Ultra-high-yield growth of vertical single-walled carbon nanotubes: Hidden roles of hydrogen and oxygen

doi:10.1073/pnas.0507064102

Ultra-high-yield growth of vertical single-walled carbon nanotubes: Hidden roles of hydrogen and oxygen

^*Department of Chemistry and Laboratory for Advanced Materials and ^†Department of Electrical Engineering, Stanford University, Stanford, CA 94305

Communicated by Calvin F. Quate, Stanford University, Stanford, CA, September 15, 2005 (received for review August 5, 2005)

Abstract

An oxygen-assisted hydrocarbon chemical vapor deposition method is developed to afford large-scale, highly reproducible, ultra-high-yield growth of vertical single-walled carbon nanotubes (V-SWNTs). It is revealed that reactive hydrogen species, inevitable in hydrocarbon-based growth, are damaging to the formation of sp²-like SWNTs in a diameter-dependent manner. The addition of oxygen scavenges H species and provides a powerful control over the C/H ratio to favor SWNT growth. The revelation of the roles played by hydrogen and oxygen leads to a unified and universal optimum-growth condition for SWNTs. Further, a versatile method is developed to form V-SWNT films on any substrate, lifting a major substrate-type limitation for aligned SWNTs.

Footnotes

↵ ‡ To whom correspondence should be addressed. E-mail: hdai{at}stanford.edu.
Author contributions: H.D. designed research; G.Z., D.M., L.Z., A.J., Y.L., E.Y., Q.W., and J.P.M. performed research; Y.N. and J.G. contributed new reagents/analytic tools; G.Z., D.M., and H.D. analyzed data; and H.D. wrote the paper.
Conflict of interest statement: No conflicts declared.
Abbreviations: SWNT, single-walled carbon nanotube; V-SWNT, vertical SWNT; CVD, chemical vapor deposition; PECVD, plasma-enhanced CVD; AFM, atomic force microscopy; sccm, standard cubic cm/min; SEM, scanning EM; TEM, transmission EM.