title: Synthesis of subnanometer-diameter vertically aligned single-walled carbon nanotubes with copper-anchored cobalt catalysts.
abstract: We synthesize vertically aligned single-walled carbon nanotubes (VA-SWNTs) with subnanometer diameters on quartz (and SiO2/Si) substrates by alcohol CVD using Cu-anchored Co catalysts. The uniform VA-SWNTs with a nanotube diameter of 1 nm are synthesized at a CVD temperature of 800 °C and have a thickness of several tens of μm. The diameter of SWNTs was reduced to 0.75 nm at 650 °C with the G/D ratio maintained above 24. Scanning transmission electron microscopy energy-dispersive X-ray spectroscopy (EDS-STEM) and high angle annular dark field (HAADF-STEM) imaging of the Co/Cu bimetallic catalyst system showed that Co catalysts were captured and anchored by adjacent Cu nanoparticles, and thus were prevented from coalescing into a larger size, which contributed to the small diameter of SWNTs. The correlation between the catalyst size and the SWNT diameter was experimentally clarified. The subnanometer-diameter and high-quality SWNTs are expected to pave the way to replace silicon for next-generation optoelectronic and photovoltaic devices.
authors.affiliation: Department of Mechanical Engineering, The University of Tokyo, 7-3-1 Hongo, Tokyo 113-8656, Japan. maruyama@photon.t.u-tokyo.ac.jp.
authors.forename: Kehang
authors.initials: K
authors.lastname: Cui
authors.affiliation: Institute of Engineering Innovation, The University of Tokyo, 2-11-16 Yayoi, Tokyo 113-8656, Japan.
authors.forename: Akihito
authors.initials: A
authors.lastname: Kumamoto
authors.affiliation: Department of Mechanical Engineering, The University of Tokyo, 7-3-1 Hongo, Tokyo 113-8656, Japan. maruyama@photon.t.u-tokyo.ac.jp.
authors.forename: Rong
authors.initials: R
authors.lastname: Xiang
authors.affiliation: Department of Mechanical Engineering, The University of Tokyo, 7-3-1 Hongo, Tokyo 113-8656, Japan. maruyama@photon.t.u-tokyo.ac.jp.
authors.forename: Hua
authors.initials: H
authors.lastname: An
authors.affiliation: Department of Mechanical Engineering, The University of Tokyo, 7-3-1 Hongo, Tokyo 113-8656, Japan. maruyama@photon.t.u-tokyo.ac.jp and Department of Chemical and Biomolecular Engineering, Rice University, Texas 77005, USA.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Wang
authors.affiliation: Department of Mechanical Engineering, The University of Tokyo, 7-3-1 Hongo, Tokyo 113-8656, Japan. maruyama@photon.t.u-tokyo.ac.jp.
authors.forename: Taiki
authors.initials: T
authors.lastname: Inoue
authors.affiliation: Department of Mechanical Engineering, The University of Tokyo, 7-3-1 Hongo, Tokyo 113-8656, Japan. maruyama@photon.t.u-tokyo.ac.jp.
authors.forename: Shohei
authors.initials: S
authors.lastname: Chiashi
authors.affiliation: Institute of Engineering Innovation, The University of Tokyo, 2-11-16 Yayoi, Tokyo 113-8656, Japan.
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Ikuhara
authors.affiliation: Department of Mechanical Engineering, The University of Tokyo, 7-3-1 Hongo, Tokyo 113-8656, Japan. maruyama@photon.t.u-tokyo.ac.jp and Energy NanoEngineering Laboratory, National Institute of Advanced Industrial Science and Technology (AIST), 1-2-1 Namiki, Tsukuba 305-8564, Japan.
authors.forename: Shigeo
authors.initials: S
authors.lastname: Maruyama