Chirality specific and spatially uniform synthesis of single-walled carbon nanotubes from a sputtered Co–W bimetallic catalyst

Abstract

Synthesis of single-walled carbon nanotubes (SWNTs) with well-defined atomic arrangements has been widely recognized in the past few decades as the biggest challenge in the SWNT community, and has become a bottleneck for the application of SWNTs in nano-electronics. Here, we report a selective synthesis of (12, 6) SWNTs with an enrichment of 50%-70% by chemical vapor deposition (CVD) using sputtered Co-W as a catalyst. This is achieved under much milder reduction and growth conditions than those in the previous report using transition-metal molecule clusters as catalyst precursors (Nature, 2014, 510, 522). Meanwhile, in-plane transmission electron microscopy unambiguously identified an intermediate structure of Co6W6C, which is strongly associated with selective growth. However, most of the W atoms disappear after a 5 min CVD growth, which implies that anchoring W may be important in this puzzling Co-W system.

Single‐Walled Carbon Nanotubes in Emerging Solar Cells: Synthesis and Electrode Applications

“…[78] This Co-W combination forms an intermetallic Co 7 W 6 compound, which is solid at a high temperature. [81] In contrast to the previous strategy in which catalyst structure and facet determined the chirality, Zhang and colleagues proposed that both catalyst symmetry and the SWNT growth kinetics are important ( Figure 4c). In this work, they used Raman spectroscopy to check all SWNTs oneby-one and obtained statistical data that were difficult to achieve before.…”

Environmental transmission electron microscopy investigations of Pt-Fe2O3 nanoparticles for nucleating carbon nanotubes

“…As indicated by TEM investigations of WCo catalysts, [6,7] it is complicated to assign the active components for SWCNT growth, the structure and the composition of which could change with prolonged reaction time. In CO hydrogenation, the addition of Pt substantially improves the reducibility of Fe2O3, [17] which can be ascribed to the spillover effect of reductive species on Pt.…”

“…Chiral map of SWCNTs without 7 large diameter ones, namely, (24,6), (17,15), (14,13), (28,6), (16,12), . There is no high selectivity to certain (n, m) species, but (8,4), (7,6), (8,6), (9, 7), (9,8) and (10,6) tubes occupy more than 37% of the total.…”

“…Of numerous catalysts studied, bimetallic catalysts have attracted particular interests due to their high activity and better control over SWCNT structures by 3 chemical vapor deposition (CVD) technique. As the result of adding a second metal, catalysts, such as CoMo, [2] CuFe, [3] RuFe, [4] PtCo [5] and WCo, [6,7] lead to higher carbon nanotube yields and narrower chirality distributions compared to their monometallic counterparts. In spite of these progresses, secret behinds the successful growth is far from being clarified.…”

“…For example, a mysterious WCo bimetallic system has been reported by two research groups to selectively grow (12,6) SWCNTs. [6,7] Yang et al [6] proposed that the fabrication of stable W6Co7 alloy is responsible for the preferential synthesis of (12,6) SWCNT. While recent work by An et al [7] identified an intermediate structure of…”