Chiral-Selective Growth of Single-Walled Carbon Nanotubes on Lattice-Mismatched Epitaxial Cobalt Nanoparticles

Abstract

Controlling chirality in growth of single-walled carbon nanotubes (SWNTs) is important for exploiting their practical applications. For long it has been conceptually conceived that the structural control of SWNTs is potentially achievable by fabricating nanoparticle catalysts with proper structures on crystalline substrates via epitaxial growth techniques. Here, we have accomplished epitaxial formation of monometallic Co nanoparticles with well-defined crystal structure, and its use as a catalyst in the selective growth of SWNTs. Dynamics of Co nanoparticles formation and SWNT growth inside an atomic-resolution environmental transmission electron microscope at a low CO pressure was recorded. We achieved highly preferential growth of semiconducting SWNTs (~90%) with an exceptionally large population of (6, 5) tubes (53%) in an ambient CO atmosphere. Particularly, we also demonstrated high enrichment in (7, 6) and (9, 4) at a low growth temperature. These findings open new perspectives both for structural control of SWNTs and for elucidating the growth mechanisms.

Understanding the “Activation” of the Nanocluster [HxPMo12O40⊂H4Mo72Fe30(O2CMe)15O254(H2O)98-y(EtOH)y] for Low Temperature Growth of Carbon Nanotubes

“…Current CVD growth generally produces a mixture of diameters and chiralities unsuitable for applications, such as electronics, that require defined structures. However, limited control over CNT morphology has been reported by tuning CVD growth conditions, such as gaseous composition, substrate, and growth temperature [4][5][6]. Of particular interest are the reports of narrowed chirality and diameter distributions at lower growth temperatures [6,7].…”

“…However, limited control over CNT morphology has been reported by tuning CVD growth conditions, such as gaseous composition, substrate, and growth temperature [4][5][6]. Of particular interest are the reports of narrowed chirality and diameter distributions at lower growth temperatures [6,7]. Lowering growth temperature is an attractive approach given the distinct economic impact on commercialization and desire for compatible processing in electronics.…”

“…Considering the problems in controlling the composition and size of binary metal oxide nanoparticles [12] single molecular precursors would be considered an ideal solution: given the unique composition and hence size of the final nanoparticle. Recently, Li et al used the molecular nanocluster Na 15 [Na 3 ,{Co(H 2 O) 4 (12,6), (14,4), and (16,0) CNTs in efficiencies of 92, 97, and 80% respectively [13][14][15]. They propose the high chiral selectivity arises from two key factors: 1) the excellent matching between the (n,m) nanotube chirality and the Miller (plane) indices of the l-phase W 6 Co 7 alloy, and 2) the stability of the high melting point alloy that maintains its well-defined structure under CVD conditions.…”

Fe Ti O based catalyst for large-chiral-angle single-walled carbon nanotube growth

“…Indeed, many growth parameters involved in CVD, including catalyst composition [12,13,[18][19][20], catalyst state [17] , carbon source [21,22], reaction temperature [12,13,23,24] and metal-support interactions [25,26], all affect the SWNT growth results, making chiralselective SWNT growth extremely difficult. Among all the above parameters, catalyst is known as the most important parameter in defining SWNT chirality distribution.…”

“…Solid solutions arise recently as promising catalysts for achieving SWNTs with specific chiralities [13,19]. This is because the solid solution offers additional degree of freedom for regulating the morphology and structure of the active catalyst component.…”