Chirality specific and spatially uniform synthesis of single-walled carbon nanotubes from a sputtered Co–W bimetallic catalyst†
* Corresponding authors
a
Department of Mechanical Engineering, The University of Tokyo, Tokyo 113-8656, Japan
E-mail:
maruyama@photon.t.u-tokyo.ac.jp, xiangrong@photon.t.u-tokyo.ac.jp
b Institute of Engineering Innovation, The University of Tokyo, Tokyo 113-8656, Japan
c Energy NanoEngineering Laboratory, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8564, Japan
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.