Hisanori Shinohara

Find an error

Name:

Organization: Nagoya University , Japan

Department: Department of Chemistry and Institute for Advanced Research

Title: Professor(PhD)

TOPICS

Physical Chemistry

Material Chemistry

Carbon Nanotubes

Chemicals
References

Modulation of the Local Density of States of Carbon Nanotubes by Encapsulation of Europium Nanowires As Observed by Scanning Tunneling Microscopy and Spectroscopy

Co-reporter:Terunobu Nakanishi, Ryo Kitaura, Takazumi Kawai, Susumu Okada, Shoji Yoshida, Osamu Takeuchi, Hidemi Shigekawa, and Hisanori Shinohara

The Journal of Physical Chemistry C August 24, 2017 Volume 121(Issue 33) pp:18195-18195

Publication Date(Web):July 31, 2017

DOI:10.1021/acs.jpcc.7b04047

Modulation of the local density of states of single-wall carbon nanotubes (SWCNTs) is induced by the encapsulation of europium nanowires (EuNWs). The observation of these modulated density of states using scanning tunneling microscopy/spectroscopy combined with density functional theory calculations is reported. The electronic modulation of SWCNTs by encapsulation of EuNWs is revealed as a Fermi level shift, band gap reduction, and the emergence of localized states in the gap. The present results show that the electronic interaction between EuNWs and SWCNTs is much stronger than that previously reported for nanomaterials encapsulated in SWCNTs.

Fabrication and In Situ Transmission Electron Microscope Characterization of Free-Standing Graphene Nanoribbon Devices

Co-reporter:Qing Wang, Ryo Kitaura, Shoji Suzuki, Yuhei Miyauchi, Kazunari Matsuda, Yuta Yamamoto, Shigeo Arai, and Hisanori Shinohara

ACS Nano 2016 Volume 10(Issue 1) pp:1475

Publication Date(Web):January 5, 2016

DOI:10.1021/acsnano.5b06975

Edge-dependent electronic properties of graphene nanoribbons (GNRs) have attracted intense interests. To fully understand the electronic properties of GNRs, the combination of precise structural characterization and electronic property measurement is essential. For this purpose, two experimental techniques using free-standing GNR devices have been developed, which leads to the simultaneous characterization of electronic properties and structures of GNRs. Free-standing graphene has been sculpted by a focused electron beam in transmission electron microscope (TEM) and then purified and narrowed by Joule heating down to several nanometer width. Structure-dependent electronic properties are observed in TEM, and significant increase in sheet resistance and semiconducting behavior become more salient as the width of GNR decreases. The narrowest GNR width we obtained with the present method is about 1.6 nm with a large transport gap of 400 meV.Keywords: band gap; free-standing structure; graphene nanoribbon; in situ TEM characterization; transport measurement;

Near-Infrared Photoluminescence Properties of Endohedral Mono- and Dithulium Metallofullerenes

Co-reporter:Zhiyong Wang, Noriko Izumi, Yusuke Nakanishi, Takeshi Koyama, Toshiki Sugai, Masayoshi Tange, Toshiya Okazaki, and Hisanori Shinohara

ACS Nano 2016 Volume 10(Issue 4) pp:4282

Publication Date(Web):April 8, 2016

DOI:10.1021/acsnano.5b07780

The optical properties of endohedral metallofullerene molecules can be tuned by changing the fullerene size as well as the number of metal atoms inside the fullerene cages. In this work we have synthesized and isolated a series of mono- and dithulium metallofullerenes, including Tm@C82 (isomers I, II, III, IV), Tm@C88 (I–IV), Tm2@C82 (I–III), and (Tm2C2)@C82 (I–III). Near-infrared photoluminescence is observed from the thulium metallofullerenes. By changing the number of Tm ion in the fullerene cage, we have found that one can vary and tune the photoluminescence from 1200 to 1300–2000 nm observed for Tm2+ (4f13) in Tm@C88 and Tm3+ (4f12) in (Tm2C2)@C82, respectively. The photoluminescence intensity depends sensitively on the fullerene cages. (Tm2C2)@C82 (III) exhibits the highest photoluminescence intensity among the three structural isomers because of its large HOMO–LUMO energy gap.Keywords: fullerene; lanthanide; metallofullerene; photoluminescence; thulium

Isolation and Structure Determination of a Missing Endohedral Fullerene La@C70 through InSitu Trifluoromethylation

Co-reporter:Dr. Zhiyong Wang;Dr. Shinobu Aoyagi;Dr. Haruka Omachi;Dr. Ryo Kitaura;Dr. Hisanori Shinohara

Angewandte Chemie International Edition 2016 Volume 55( Issue 1) pp:199-202

Publication Date(Web):

DOI:10.1002/anie.201508082

Abstract

D_5h-symmetric fullerene C₇₀ (D_5h-C₇₀) is one of the most abundant members of the fullerene family. One longstanding mystery in the field of fullerene chemistry is whether D_5h-C₇₀ is capable of accommodating a rare-earth metal atom to form an endohedral metallofullerene M@D_5h-C₇₀, which would be expected to show novel electronic properties. The molecular structure of La@C₇₀ remains unresolved since its discovery three decades ago because of its extremely high instability under ambient conditions and insolubility in organic solvents. Herein, we report the single-crystal X-ray structure of La@C₇₀(CF₃)₃, which was obtained through in situ exohedral functionalization by means of trifluoromethylation. The X-ray crystallographic study reveals that La@C₇₀(CF₃)₃ is the first example of an endohedral rare-earth fullerene based on D_5h-C₇₀. The dramatically enhanced stability of La@C₇₀(CF₃)₃ compared to La@C₇₀ can be ascribed to trifluoromethylation-induced bandgap enlargement.

Isolation and Structure Determination of a Missing Endohedral Fullerene La@C70 through InSitu Trifluoromethylation

Co-reporter:Dr. Zhiyong Wang;Dr. Shinobu Aoyagi;Dr. Haruka Omachi;Dr. Ryo Kitaura;Dr. Hisanori Shinohara

Angewandte Chemie 2016 Volume 128( Issue 1) pp:207-210

Publication Date(Web):

DOI:10.1002/ange.201508082

Abstract

Fabrication and Optical Probing of Highly Extended, Ultrathin Graphene Nanoribbons in Carbon Nanotubes

Co-reporter:Hong En Lim, Yasumitsu Miyata, Miho Fujihara, Susumu Okada, Zheng Liu, Arifin, Kayoko Sato, Haruka Omachi, Ryo Kitaura, Stephan Irle, Kazu Suenaga, and Hisanori Shinohara

ACS Nano 2015 Volume 9(Issue 5) pp:5034

Publication Date(Web):April 13, 2015

DOI:10.1021/nn507408m

Nanotemplated growth of graphene nanoribbons (GNRs) inside carbon nanotubes is a promising mean to fabricate ultrathin ribbons with desired side edge configuration. We report the optical properties of the GNRs formed in single-wall carbon nanotubes. When coronene is used as the precursor, extended GNRs are grown via a high-temperature annealing at 700 °C. Their optical responses are probed through the diazonium-based side-wall functionalization, which effectively suppresses the excitonic absorption peaks of the nanotubes without damaging the inner GNRs. Differential absorption spectra clearly show two distinct peaks around 1.5 and 3.4 eV. These peaks are assigned to the optical transitions between the van Hove singularities in the density of state of the GNRs in qualitative agreement with the first-principles calculations. Resonance Raman spectra and transmission electron microscope observations also support the formation of long GNRs.Keywords: graphene nanoribbons; functionalization; optical absorption; single-wall carbon nanotubes;

Selective Formation of Zigzag Edges in Graphene Cracks

Co-reporter:Miho Fujihara, Ryosuke Inoue, Rei Kurita, Toshiyuki Taniuchi, Yoshihito Motoyui, Shik Shin, Fumio Komori, Yutaka Maniwa, Hisanori Shinohara, and Yasumitsu Miyata

ACS Nano 2015 Volume 9(Issue 9) pp:9027

Publication Date(Web):August 19, 2015

DOI:10.1021/acsnano.5b03079

We report the thermally induced unconventional cracking of graphene to generate zigzag edges. This crystallography-selective cracking was observed for as-grown graphene films immediately following the cooling process subsequent to chemical vapor deposition (CVD) on Cu foil. Results from Raman spectroscopy show that the crack-derived edges have smoother zigzag edges than the chemically formed grain edges of CVD graphene. Using these cracks as nanogaps, we were also able to demonstrate the carrier tuning of graphene through the electric field effect. Statistical analysis of visual observations indicated that the crack formation results from uniaxial tension imparted by the Cu substrates together with the stress concentration at notches in the polycrystalline graphene films. On the basis of simulation results using a simplified thermal shrinkage model, we propose that the cooling-induced tension is derived from the transient lattice expansion of narrow Cu grains imparted by the thermal shrinkage of adjacent Cu grains.Keywords: cleavage; cracking; graphene; nanogaps; zigzag edge;

Direct observation of zipper-like wall-to-wall coalescence of double-wall carbon nanotubes

Co-reporter:Sihan Zhao, Yasumitsu Miyata, Hisanori Shinohara, Ryo Kitaura

Carbon 2014 Volume 71() pp:159-165

Publication Date(Web):May 2014

DOI:10.1016/j.carbon.2014.01.024

In situ transmission electron microscope (TEM) observation has become a fairly powerful characterization method to uniquely provide the real-time information on the dynamics and kinetics of physical and chemical transformations at the nanometer scale. Here, we report a development of a high-temperature-compatible specimen heating holder equipped with a micro-sized carbon nanotube (CNT) network heater. The CNT network heater can heat samples up to extremely high temperature, as high as >2000 °C, while minimizing the spatial drift of the samples induced by the heating. This has directly led to a real-time imaging of a purely thermally-driven nano-welding process between two parallel-aligned double-wall carbon nanotubes (DWCNTs) using low-voltage TEM (80 keV); a single larger-diameter DWCNT was formed after the reaction and the reaction rate was determined. This technique developed is basically applicable to the in situ TEM study of various thermal-driven solid-phase dynamical changes/reactions and should provide more significant insight on nanoscience and nanothermodynamics.

Rayleigh scattering studies on inter-layer interactions in structure-defined individual double-wall carbon nanotubes

Co-reporter:Sihan Zhao;Tomoya Kitagawa;Yuhei Miyauchi;Kazunari Matsuda

Nano Research 2014 Volume 7( Issue 10) pp:1548-1555

Publication Date(Web):2014 October

DOI:10.1007/s12274-014-0515-y

Although the inter-layer coupling in layered materials has attracted considerable interest due to its importance in determining physical properties of two-dimensional systems, studies on the inter-layer coupling in one-dimensional systems have so far been limited. Double-wall carbon nanotubes (DWCNTs) are one of the most fundamental and ideal model systems to study the inter-layer coupling in one-dimensional systems. In this work, Rayleigh scattering spectroscopy and transmission electron microscopy are used to characterize the electronic transition between inner-and outer-nanotubes of the exactly same individual DWCNT. We find that the inter-layer coupling is strong, leading to downshifts in most of the optical transition energies (up to ∼0.2 eV) compared to isolated CNTs. We also find that the presence of metallic tubes lead to stronger shifts. The inter-layer screening of Coulomb interactions is one of the key factors in explaining the observed results.

Direct Chemical Vapor Deposition Growth of WS2 Atomic Layers on Hexagonal Boron Nitride

Co-reporter:Mitsuhiro Okada, Takumi Sawazaki, Kenji Watanabe, Takashi Taniguch, Hiroki Hibino, Hisanori Shinohara, and Ryo Kitaura

ACS Nano 2014 Volume 8(Issue 8) pp:8273

Publication Date(Web):August 5, 2014

DOI:10.1021/nn503093k

Atomically thin transition metal dichalcogenides (TMDCs) have attracted considerable interest owing to the spin-valley coupled electronic structure and possibility in next-generation devices. Substrates are one of the most important factors to limit physical properties of atomic-layer materials, and among various substrates so far investigated, hexagonal boron nitride (hBN) is the best substrate to explore the intrinsic properties of atomic layers. Here we report direct chemical vapor deposition (CVD) growth of WS2 onto high-quality hBN using a 3-furnace CVD setup. Triangular-shaped WS2 grown on hBN have shown limited crystallographic orientation that is related to that of the underlying hBN. Photoluminescence spectra of the WS2 show an intense emission peak at 2.01 eV with a quite small fwhm of 26 meV. The sharp emission peak indicates the high quality of the present WS2 atomic layers with high crystallinity and clean interface.Keywords: CVD growth; optical properties; transition metal dichalcogenides (TMDCs)

Metal-Dependent Stability of Pristine and Functionalized Unconventional Dimetallofullerene M2@Ih-C80

Co-reporter:Zhiyong Wang ; Ryo Kitaura

The Journal of Physical Chemistry C 2014 Volume 118(Issue 25) pp:13953-13958

Publication Date(Web):June 2, 2014

DOI:10.1021/jp5028492

The unstable fullerene Ih-C80 can be stabilized greatly by encapsulation of two rare-earth metal atoms in its interior. Here we present a theoretical study on the electronic structures and stabilities of dimetallofullerene M2@Ih-C80 (M = Y, La, Gd, Lu). Density functional calculations demonstrate that La2@Ih-C80 has a closed-shell configuration, whereas Y2@Ih-C80 has a triplet ground state. Unlike La2@Ih-C80 with a high stability, Y2@Ih-C80 is found to be a highly reactive radical due to the unpaired electron distributed on the fullerene cage. Such characteristic properties of La2@Ih-C80 and Y2@Ih-C80 originate from the different energy levels of the metal-based molecular orbitals. Y2@Ih-C80 can be stabilized, however, through exterior functionalization with a CF3 group. Interestingly, metallofullerenes Gd2@Ih-C80 and Lu2@Ih-C80 have similar frontier molecular orbitals and chemical stabilities to those of Y2@Ih-C80.

Structure of Tm2 and Tm2C2 encapsulated in low-symmetry C82(Cs(6)) fullerene cage by single crystal X-ray diffraction

Co-reporter:Yuki Sado, Shinobu Aoyagi, Noriko Izumi, Ryo Kitaura, Tim Kowalczyk, Jian Wang, Stephan Irle, Eiji Nishibori, Kunihisa Sugimoto, Hisanori Shinohara

Chemical Physics Letters 2014 600() pp: 38-42

Publication Date(Web):

DOI:10.1016/j.cplett.2014.03.047

Synthesis and TEM structural characterization of C60-flattened carbon nanotube nanopeapods

Co-reporter:Qing Wang;Ryo Kitaura;Yuta Yamamoto;Shigeo Arai

Nano Research 2014 Volume 7( Issue 12) pp:1843-1848

Publication Date(Web):2014 December

DOI:10.1007/s12274-014-0544-6

A fully flattened carbon nanotube (FNT), a graphene nanoribbon (GNR) analogue, provides a hollow space at edges for endohedral doping. Due to the unique shape of the hollow space of FNTs, novel types of low-dimensional arrangements of atoms and molecules can be obtained through endohedral doping into FNTs, which provides a new type of nanopeapods. FNT-based nanopeapods have been synthesized through endohedral doping of C60, and their structural characterization with transmission electron microscopy (TEM) performed. The doping of C60 into the inner hollow space of FNTs has been carried out via the gas-phase filling method, where open-ended FNTs are sealed in a glass ampoule and heated at 723–773 K for two days. TEM observations show that most of the encapsulated C60 molecules align as single molecular chains along the edges of FNTs and that some of the C60 forms two-dimensional close-packed structures inside FNTs.

Chirally selective growth and extraction of single-wall carbon nanotubes via fullerene nano-peapods

Co-reporter:Jinying Zhang, Feng Zhou, Yasumitsu Miyata, Ryo Kitaura, Haibin Su and Hisanori Shinohara

RSC Advances 2013 vol. 3(Issue 38) pp:16954-16957

Publication Date(Web):24 Jul 2013

DOI:10.1039/C3RA43133A

Single-wall carbon nanotubes (SWCNTs) grown from C60 and C70 inside SWCNTs with diameters of 1.5 ± 0.1 nm are investigated. The as-produced SWCNTs have been extracted, separated, and characterized. The products from C70 are dominated by (7,6) and (9,4) SWCNTs, whereas those from C60 are dominated by (6,5) SWCNTs.

Rcktitelbild: Missing Small-Bandgap Metallofullerenes: Their Isolation and Electronic Properties (Angew. Chem. 45/2013)

Co-reporter:Dr. Zhiyong Wang;Yusuke Nakanishi;Shoko Noda;Hiroyuki Niwa;Dr. Jinying Zhang;Dr. Ryo Kitaura ;Dr. Hisanori Shinohara

Angewandte Chemie 2013 Volume 125( Issue 45) pp:

Publication Date(Web):

DOI:10.1002/ange.201308412

Missing Small-Bandgap Metallofullerenes: Their Isolation and Electronic Properties

Co-reporter:Dr. Zhiyong Wang;Yusuke Nakanishi;Shoko Noda;Hiroyuki Niwa;Dr. Jinying Zhang;Dr. Ryo Kitaura ;Dr. Hisanori Shinohara

Angewandte Chemie 2013 Volume 125( Issue 45) pp:11986-11990

Publication Date(Web):

DOI:10.1002/ange.201305573

STM and STS Studies on the Density of States Modulation of Pr@C82 and Sc3C2@C80 Binary-Metallofullerene Peapods

Co-reporter:Yuki Iijima, Kazunori Ohashi, Naoki Imazu, Ryo Kitaura, Ken Kanazawa, Atsushi Taninaka, Osamu Takeuchi, Hidemi Shigekawa, and Hisanori Shinohara

The Journal of Physical Chemistry C 2013 Volume 117(Issue 14) pp:6966-6971

Publication Date(Web):March 20, 2013

DOI:10.1021/jp3128466

The density of states modulation of single-wall carbon nanotubes (SWCNTs) is induced by the encapsulation of two different kinds of metallofullerenes (Pr@C82 and Sc3C2@C80). We report the observation of the modulated density of states using scanning tunneling microscopy/spectroscopy, where the modulation is successfully reproduced by density functional theory calculation. The metallofullerene molecules in SWCNTs strongly affect the local band structures of SWCNTs. The present findings show that the local electronic structures of SWCNTs can be modified by not only varying the geometric structures of SWCNTs but also the varieties of metallofullerenes encapsulated.

Structure of Tm@C82(I) Metallofullerene by Single-Crystal X-ray Diffraction Using the 1:2 Co-Crystal with Octaethylporphyrin Nickel (Ni(OEP))

Co-reporter:Yuki Sado ; Shinobu Aoyagi ; Ryo Kitaura ; Yasumitsu Miyata ; Eiji Nishibori ; Hiroshi Sawa ; Kunihisa Sugimoto

The Journal of Physical Chemistry C 2013 Volume 117(Issue 12) pp:6437-6442

Publication Date(Web):March 4, 2013

DOI:10.1021/jp311948c

The molecular structure of Tm@C82 (isomer I) is revealed by single-crystal X-ray diffraction of the 1:2 cocrystal with nickel octaethylporphyrin (Ni(OEP)). A rotational movement of Tm@C82(I) molecule in the 1:1 cocrystal is dramatically suppressed by the coordination of two Ni(OEP) ligands in the 1:2 cocrystal. The structure of Tm@C82(I) in the crystal is explained by the orientation disorder with two different orientations. The so-obtained carbon cage structure is Cs(6)–C82. The restricted molecular orientations of Tm@C82(I) in the 1:2 cocrystal are achieved by the molecular dipole moment of Tm@C82(I) that interacts with two Ni(OEP) ligands. The present study suggests that the intermolecular interactions can reduce the degree of freedom in the orientation of spherical metallofullerene molecules in the crystals and complexes.

Evidence of Diamond Nanowires Formed inside Carbon Nanotubes from Diamantane Dicarboxylic Acid

Co-reporter:Dr. Jinying Zhang;Zhen Zhu;Dr. Yanquan Feng;Hitoshi Ishiwata;Dr. Yasumitsu Miyata;Dr. Ryo Kitaura;Dr. Jeremy E. P. Dahl;Dr. Robert M. K. Carlson;Dr. Natalie A. Fokina;Dr. Peter R. Schreiner;Dr. David Tománek;Dr. Hisanori Shinohara

Angewandte Chemie 2013 Volume 125( Issue 13) pp:3805-3809

Publication Date(Web):

DOI:10.1002/ange.201209192

Innentitelbild: Evidence of Diamond Nanowires Formed inside Carbon Nanotubes from Diamantane Dicarboxylic Acid (Angew. Chem. 13/2013)

Angewandte Chemie 2013 Volume 125( Issue 13) pp:

Publication Date(Web):

DOI:10.1002/ange.200301042

Evidence of Diamond Nanowires Formed inside Carbon Nanotubes from Diamantane Dicarboxylic Acid

Angewandte Chemie International Edition 2013 Volume 52( Issue 13) pp:3717-3721

Publication Date(Web):

DOI:10.1002/anie.201209192

Inside Cover: Evidence of Diamond Nanowires Formed inside Carbon Nanotubes from Diamantane Dicarboxylic Acid (Angew. Chem. Int. Ed. 13/2013)

Angewandte Chemie International Edition 2013 Volume 52( Issue 13) pp:

Publication Date(Web):

DOI:10.1002/anie.201301042

Missing Small-Bandgap Metallofullerenes: Their Isolation and Electronic Properties

Co-reporter:Dr. Zhiyong Wang;Yusuke Nakanishi;Shoko Noda;Hiroyuki Niwa;Dr. Jinying Zhang;Dr. Ryo Kitaura ;Dr. Hisanori Shinohara

Angewandte Chemie International Edition 2013 Volume 52( Issue 45) pp:11770-11774

Publication Date(Web):

DOI:10.1002/anie.201305573

Back Cover: Missing Small-Bandgap Metallofullerenes: Their Isolation and Electronic Properties (Angew. Chem. Int. Ed. 45/2013)

Co-reporter:Dr. Zhiyong Wang;Yusuke Nakanishi;Shoko Noda;Hiroyuki Niwa;Dr. Jinying Zhang;Dr. Ryo Kitaura ;Dr. Hisanori Shinohara

Angewandte Chemie International Edition 2013 Volume 52( Issue 45) pp:

Publication Date(Web):

DOI:10.1002/anie.201308412

A Structural Diagnostics Diagram for Metallofullerenes Encapsulating Metal Carbides and Nitrides

Co-reporter:Sachiko Maki ; Eiji Nishibori ; Ikuya Terauchi ; Masayuki Ishihara ; Shinobu Aoyagi ; Makoto Sakata ; Masaki Takata ; Hisashi Umemoto ; Takashi Inoue

Journal of the American Chemical Society 2012 Volume 135(Issue 2) pp:918-923

Publication Date(Web):December 21, 2012

DOI:10.1021/ja311070v

Systematic structural studies of 24 different kinds of endohedral metallofullerenes, MxC2n (M = La, Y, Sc, Lu, Ti, Eu, Er, Hf, Sc3N; 34 ≤ n ≤ 43), as 1:1 cocrystals with solvent toluene molecules have been carried out using synchrotron radiation powder diffraction. Thirteen of the 24 molecular structures, including five metal carbides, one metal nitride endohedral fullerene, and one hollow fullerene, have been determined by a combination of the maximum entropy method and Rietveld refinement of the X-ray diffraction data obtained. We have found that the volume for one fullerene and one toluene molecule depends linearly on the number of carbon atoms in the fullerene cage. Fifteen different kinds of metal carbide endohedral fullerenes have been identified, which can be structurally characterized from the obtained lattice constants using only this linear dependence. The linear dependence found in the present study provides a metallofullerene diagnostics diagram that may have universal importance for structural characterization of the so-called cluster endohedral fullerenes.

The Origin and Mechanism of Non-HPLC Purification of Metallofullerenes with TiCl4

Co-reporter:Zhiyong Wang, Yusuke Nakanishi, Shoko Noda, Kazuhiko Akiyama, and Hisanori Shinohara

The Journal of Physical Chemistry C 2012 Volume 116(Issue 48) pp:25563-25567

Publication Date(Web):November 12, 2012

DOI:10.1021/jp307729j

Complexation of endohedral metallofullerenes with TiCl4 has recently been shown to provide an efficient route for separation and purification of metallofullerenes from empty fullerenes in large scale. This investigation presents an in-depth study on the complex formation mechanism between fullerenes/metallofullerenes with TiCl4. The reactivity of fullerenes/metallofullerenes has been found to be critically dependent on their first oxidation potentials. A lower oxidation potential leads to a higher reactivity. The threshold in the first oxidation potential for reaction with TiCl4 is determined to be 0.62–0.72 V vs Fc/Fc+. All types of metallofullerenes with first oxidation potentials lower than this threshold can be separated from empty fullerenes. Electron transfer from metallofullerenes to TiCl4, evidenced by the change in UV–vis absorption spectrum, provides an interpretation of the relation between reactivity and oxidation potential.

Dimerization-Initiated Preferential Formation of Coronene-Based Graphene Nanoribbons in Carbon Nanotubes

Co-reporter:Miho Fujihara, Yasumitsu Miyata, Ryo Kitaura, Yoshifumi Nishimura, Cristopher Camacho, Stephan Irle, Yoko Iizumi, Toshiya Okazaki, and Hisanori Shinohara

The Journal of Physical Chemistry C 2012 Volume 116(Issue 28) pp:15141-15145

Publication Date(Web):June 19, 2012

DOI:10.1021/jp3037268

We have investigated the growth mechanism of coronene-derived graphene nanoribbons (GNRs) using two different precursors: coronene and a dimer form of coronene, so-called dicoronylene (C48H20). For both of the precursors, the formation of nanoribbon-like materials inside carbon nanotubes (CNTs) was confirmed by transmission electron microscope observations. Experimental and theoretical Raman analysis reveals that the samples also encapsulated dicoronylene and linearly condensed other coronene oligomers, which can be regarded as analogues to GNRs. Interestingly, it was found that the present doping condition of coronene yields dicoronylene prior to encapsulation due to the thermal dimerization of coronene. These results indicate that the dimerization before the encapsulation drives the preferential formation of the coronene-based GNRs within CNTs.

In pursuit of nanocarbons

Co-reporter:Hisanori Shinohara

The Chemical Record 2012 Volume 12( Issue 3) pp:296-305

Publication Date(Web):

DOI:10.1002/tcr.201100037

Abstract

With the advent of the Krätschmer-Huffman historical breakthrough on the macroscopic synthesis of C₆₀ in the late summer of 1990, I decided to stop all my research so far in the area of spectroscopy of gas-phase molecular microclusters. Since then, my odyssey in and quest for the so-called nanocarbons started. Thanks to the brand-new and enchanting world of fullerenes, metallofullerenes, carbon nanotubes and nano-peapods, I have been able to entertain (and still am entertaining!) “the pleasure of finding things out”, as Richard Feynman once put it in an interview by a BBC television program in 1981. I believe that as long as one has big dreams and lays the groundwork for the dreams, one will achieve them. My quest for nanocarbons is still on its way. DOI 10.1002/tcr.201100037

Transformation of ionic liquid into carbon nanotubes in confined nanospace

Co-reporter:Shimou Chen, Hong En Lim, Yasumitsu Miyata, Ryo Kitaura, Yoshio Bando, Dmitri Golberg and Hisanori Shinohara

Chemical Communications 2011 vol. 47(Issue 37) pp:10368-10370

Publication Date(Web):16 Aug 2011

DOI:10.1039/C1CC14154F

We have developed a two-step filling process for the nano-reaction of ionic liquid in a tip-closed SWNT, where fullerenes are inserted at the end of the host SWNT as a plug to prevent the leakage of the confined ionic liquid during heat treatment.

Growth of large-diameter (∼4 nm) single-wall carbon nanotubes in the nanospace of mesoporous material SBA-15

Co-reporter:Keita Kobayashi, Ryo Kitaura, Fumihiro Nishimura, Hirofumi Yoshikawa, Kunio Awaga, Hisanori Shinohara

Carbon 2011 Volume 49(Issue 15) pp:5173-5179

Publication Date(Web):December 2011

DOI:10.1016/j.carbon.2011.07.033

Single-wall carbon nanotubes (SWCNTs) have been synthesized by supported-catalyst chemical vapor deposition (CCVD) using one-dimensional (1D) channels of mesoporous silica (SBA-15; mean channel diameter, 6.0 nm) functionalized with carboxyl groups where Co and Fe complexes are encapsulated. The synthesized SWCNTs have much larger diameters than the SWCNTs synthesized by conventional CCVD. Transmission electron microscope observations reveal that large-diameter SWCNTs (<4.2 nm) are grown in 1D channels of SBA-15. Large metal particles formed in the channels should play an important role in the growth of the SWCNTs with larger diameters.

Length-sorted semiconducting carbon nanotubes for high-mobility thin film transistors

Co-reporter:Yasumitsu Miyata;Kazunari Shiozawa;Yuki Asada;Yutaka Ohno;Ryo Kitaura

Nano Research 2011 Volume 4( Issue 10) pp:963-970

Publication Date(Web):2011 October

DOI:10.1007/s12274-011-0152-7

Irregular Modulation of Density-of-States of Nano-Peapods Encapsulating Gd@C82 Metallofullerenes

Co-reporter:Kazunori Ohashi ; Naoki Imazu ; Ryo Kitaura

The Journal of Physical Chemistry C 2011 Volume 115(Issue 10) pp:3968-3972

Publication Date(Web):February 23, 2011

DOI:10.1021/jp1123426

The modifications of density-of-states (DOS) of single-wall carbon nanotubes (SWCNTs) induced by encapsulation of Gd@C82 metallofullerenes have been studied by a combination of scanning tunneling microscopy/spectroscopy (STM/STS) and DFT. We demonstrate that internal orientation of Gd@C82 molecules inside SWCNTs can strongly affect the electronic structure of SWCNTs. The present findings suggest that not only encapsulated molecules but also their molecular orientations can be a tunable parameter with which we can modulate local electronic structures of SWCNTs.

Growth of Linear Carbon Chains inside Thin Double-Wall Carbon Nanotubes

Co-reporter:C. Zhao ; R. Kitaura ; H. Hara ; S. Irle ;H. Shinohara

The Journal of Physical Chemistry C 2011 Volume 115(Issue 27) pp:13166-13170

Publication Date(Web):June 7, 2011

DOI:10.1021/jp201647m

Fusion reactions of size-selected linear polyyne molecules, C10H2, in the ultrathin one-dimensional (1D) nanospace of double wall carbon nanotubes (DWCNTs) have been observed, leading to the formation of very long linear carbon chains. The formation and growth of long linear carbon chains is investigated by Raman spectroscopy and density-functional tight-binding-based molecular dynamics simulations. The high-resolution transmission electron microscope images of C10H2@DWCNTs show that the encapsulated linear C10H2 molecules have a length of 1.2–1.3 nm. After the high temperature annealing at 1073–1273 K under high vacuum conditions, new Raman bands appear at 1800–1850 cm–1, and the Raman bands arising from encapsulated pristine polyyne molecules at 2000–2200 cm–1 completely disappear. This is clear evidence that a fusion reaction occurs to form long linear carbon chains inside the 1D nanospace of DWCNTs.

Direct HRTEM Observation of Ultrathin Freestanding Ionic Liquid Film on Carbon Nanotube Grid

Co-reporter:Shimou Chen, Keita Kobayashi, Ryo Kitaura, Yasumitsu Miyata, and Hisanori Shinohara

ACS Nano 2011 Volume 5(Issue 6) pp:4902

Publication Date(Web):May 19, 2011

DOI:10.1021/nn2009968

Direct imaging of liquids by electron microscopy has been extremely difficult due to their high volatility. Ionic liquids are a unique liquid material with almost zero vapor pressure, which allows us to characterize them under high-vacuum conditions. Here we report the first direct observation of the microstructure and phase behavior of an imidazolium-based room-temperature ionic liquid by high-resolution transmission electron microscopy with the aid of a special carbon nanotube network, which is able to support a freestanding ultrathin ionic liquid film on its nanosized holes. It was found that the existence of cluster structures is one of the intrinsic properties of the ionic liquid in its whole liquid phase range. Furthermore, the size and mobility of the clusters play an important role during phase transition of the ionic liquid. We show that the direct HRTEM imaging on freestanding liquid film is a powerful technique to obtain insight into the structure of ionic liquids and their phase behavior. The present study can provide an important starting point for more sophisticated structural studies on the microstructure of liquidus materials.Keywords: cluster; electron microscopy; freestanding liquid film; ionic liquid; phase transition

Thin-Film Transistors with Length-Sorted DNA-Wrapped Single-Wall Carbon Nanotubes

Co-reporter:Yuki Asada, Yasumitsu Miyata, Kazunari Shiozawa, Yutaka Ohno, Ryo Kitaura, Takashi Mizutani, and Hisanori Shinohara

The Journal of Physical Chemistry C 2011 Volume 115(Issue 1) pp:270-273

Publication Date(Web):December 13, 2010

DOI:10.1021/jp107361n

The present experimental study provides a detailed characterization of the single-wall carbon nanotube (SWNT) length effect on the device characteristics of DNA-wrapped SWNT-network thin-film transistors (TFTs). DNA-assisted dispersion and length separation by high-performance liquid chromatography are used to prepare the SWNTs with average lengths of 400 and 200 nm. The TFTs of both SWNTs exhibit high on/off current ratios of 104−106 and mobilities of 0.4−1.3 cm2/(V s) by optimizing the film density of SWNTs. The optimized density of 200 nm SWNTs is found to be higher than that of 400 nm SWNTs as expected by the percolation theory of two-dimensional random networks, where shorter length SWNTs can maintain high on current despite increasing in the number of SWNT junctions. The present result is an important indicator for realizing high-performance TFTs constructed from SWNTs having desired length.

High-Performance Thin-Film Transistors with DNA-Assisted Solution Processing of Isolated Single-Walled Carbon Nanotubes

Co-reporter:Yuki Asada;Yasumitsu Miyata;Yutaka Ohno;Ryo Kitaura;Toshiki Sugai;Takashi Mizutani

Advanced Materials 2010 Volume 22( Issue 24) pp:2698-2701

Publication Date(Web):

DOI:10.1002/adma.200904006

CNT Thin-Film Transistors: High-Performance Thin-Film Transistors with DNA-Assisted Solution Processing of Isolated Single-Walled Carbon Nanotubes (Adv. Mater. 24/2010)

Co-reporter:Yuki Asada;Yasumitsu Miyata;Yutaka Ohno;Ryo Kitaura;Toshiki Sugai;Takashi Mizutani

Advanced Materials 2010 Volume 22( Issue 24) pp:

Publication Date(Web):

DOI:10.1002/adma.201090083

Synthesis and UHV-STM observation of the Td-symmetric Lu metallofullerene: Lu2@C76(Td)

Co-reporter:Hisashi Umemoto, Kazunori Ohashi, Takashi Inoue, Nobuyuki Fukui, Toshiki Sugai and Hisanori Shinohara

Chemical Communications 2010 vol. 46(Issue 31) pp:5653-5655

Publication Date(Web):21 Jun 2010

DOI:10.1039/C0CC00824A

The first Td-symmetric lutetium metallofullerene, Lu2@C76, has been synthesized, isolated, and characterized. Because of the charge transfer from the encapsulated Lu atoms to the Td-C76 fullerene cage, the otherwise unstable Td-C76 fullerene can be significantly stabilized as a Lu2@C76 fullerene. Both STM and STS results are consistent with a charge state of (Lu2)6+@C766−(Td).

Molecular recognition of La@C82 endohedral metallofullerene by an isophthaloyl-bridged porphyrin dimer

Co-reporter:Georgia Pagona, Solon P. Economopoulos, Takayuki Aono, Yasumitsu Miyata, Hisanori Shinohara, Nikos Tagmatarchis

Tetrahedron Letters 2010 Volume 51(Issue 45) pp:5896-5899

Publication Date(Web):10 November 2010

DOI:10.1016/j.tetlet.2010.08.111

La@C82 is recognized by an isophthaloyl-bridged porphyrin dimer forming a stable 1:1 supramolecular complex with an association constant Kassoc = (67.3 ± 3.2) × 103 M−1.La@C82 is recognized by an isophthaloyl-bridged porphyrin dimer forming a stable 1:1 supramolecular complex.

Solution-Phase Extraction of Ultrathin Inner Shells from Double-Wall Carbon Nanotubes

Co-reporter:Yasumitsu Miyata, Marie Suzuki, Miho Fujihara, Yuki Asada, Ryo Kitaura, and Hisanori Shinohara

ACS Nano 2010 Volume 4(Issue 10) pp:5807

Publication Date(Web):September 9, 2010

DOI:10.1021/nn1015665

We present an efficient method to extract inner shells of double-wall carbon nanotubes (DWCNTs) in liquid phase. The extraction of inner from outer shells is achieved by cutting the DWCNTs with vigorous sonication in water containing surfactants. The extracted shells are perfectly isolated single-wall carbon nanotubes (SWCNTs) and can be separated using density gradient ultracentrifugation. Statistical analysis using high-resolution transmission electron microscopy reveals that the enrichment of SWCNTs with narrow diameter (0.62−1.0 nm) up to 100% is achieved from highly pure DWCNTs. Furthermore, the (5,4) SWCNTs, which have the diameter of 0.62 nm, are concentrated. Our findings provide a novel way to obtain very narrow, highly isolated SWCNTs with ultraclean surface that have not been obtained in conventional synthesis methods.Keywords: density gradient ultracentrifugation; double-wall carbon nanotubes; separation; single-wall carbon nanotubes; transmission electron microscopy

Morphology and Melting Behavior of Ionic Liquids inside Single-Walled Carbon Nanotubes

Co-reporter:Shimou Chen ; Keita Kobayashi ; Yasumitsu Miyata ; Naoki Imazu ; Takeshi Saito ; Ryo Kitaura

Journal of the American Chemical Society 2009 Volume 131(Issue 41) pp:14850-14856

Publication Date(Web):September 25, 2009

DOI:10.1021/ja904283d

We report the synthesis and characterization of single-walled carbon nanotubes (SWNTs) filled with a zinc-containing quaternary ammonium based ionic liquid (ChZnCl3) inside. The threshold SWNT diameter for efficient encapsulation was determined to be ca. 0.97 nm. Different morphologies of the encapsulated ChZnCl3 such as single-chain, double-helix, zigzag tubes, and random tubes were observed. The melting of ChZnCl3 ionic liquid into “nanofluid” inside SWNTs was investigated by in situ TEM electron beam irradiation and compared with a high-temperature heat treatment. The thermal-decomposition temperature of the ChZnCl3 ionic liquid confined in the SWNTs was much higher than in the bulk system. Furthermore, the doping effect of the encapsulated ChZnCl3 on the host SWNTs can be varied (from p-type to n-type) by gradually reducing the filling ratio. The versatility of ionic liquids and the unique phase transition observed inside the SWNTs provide a new opportunity for modulating the electronic properties of carbon nanotubes.

Fabrication of single-wall carbon nanotubes within the channels of a mesoporous material by catalyst-supported chemical vapor deposition

Co-reporter:Keita Kobayashi, Ryo Kitaura, Yoko Kumai, Yastomo Goto, Sinji Imagaki, Hisanori Shinohara

Carbon 2009 Volume 47(Issue 3) pp:722-730

Publication Date(Web):March 2009

DOI:10.1016/j.carbon.2008.11.011

Diameter-controlled single-wall carbon nanotubes (SWCNTs) have been synthesized using Co, Fe/Co and Rh/Pd alloy nanoparticles trapped within the one-dimensional channels of a mesoporous materials (Folded Sheets Mesoporous material: FSM-16) by catalyst-supported chemical vapor deposition (CCVD) using ethanol as carbon source at 973–1173 K. The SWCNTs synthesized are characterized by transmission electron microscopy, Raman spectroscopy and photoluminescence spectroscopy. The yield, diameter distribution and quality of the SWCNTs strongly depend on the reaction temperature during CCVD. The product synthesized at 1173 K contains only SWCNTs, in marked contrast to those synthesized at lower temperatures. As the reaction temperature decreases, the relative abundance of multi-wall carbon nanotubes against SWCNTs significantly increases, whereas the mean diameter of SWCNTs increases as reaction temperature increases. The results show that a careful control of the reaction temperature is crucial to fabricate diameter-controlled SWCNTs from the channels of FSM-16.

Determining exact molar absorbance coefficients of single-wall carbon nanotubes

Co-reporter:Shota Kuwahara, Toshiki Sugai and Hisanori Shinohara

Physical Chemistry Chemical Physics 2009 vol. 11(Issue 7) pp:1091-1097

Publication Date(Web):06 Jan 2009

DOI:10.1039/B814008A

A new spray technique coupled with atomic force microscopy is developed to obtain the absolute number of carbon nanotubes in a unit volume. By using the present technique, the absolute molar absorbance coefficient of single-wall carbon nanotubes (SWNTs) has been determined and found to be ca. 2–5 × 107 L mol−1 cm−1. This molar absorbance coefficient enables us to deal with carbon nanotubes as individual “molecules” and to adequately compare them with other related compounds such as fullerenes. The absorbance coefficient of SWNTs is found to be only 100 times as large as those of fullerenes. This indicates that the large aspect ratio, random orientation in dispersion solution and anisotropic absorption properties of SWNTs substantially reduce their absorption probability.

Unsynchronized Diameter Changes of Double-Wall Carbon Nanotubes during Chemical Vapour Deposition Growth

Co-reporter:Guoqing Ning Dr. Dr.

Chemistry – An Asian Journal 2009 Volume 4( Issue 6) pp:955-960

Publication Date(Web):

DOI:10.1002/asia.200800347

Fabrication, Purification, and Characterization of Double-Wall Carbon Nanotubes via Pulsed Arc Discharge

Co-reporter:Hiromichi Yoshida, Toshiki Sugai and Hisanori Shinohara

The Journal of Physical Chemistry C 2008 Volume 112(Issue 50) pp:19908-19915

Publication Date(Web):2017-2-22

DOI:10.1021/jp806529v

Fabrication of high-purity double-wall carbon nanotubes (DWNTs) with purity more than 95% has been achieved by developing synthetic and purification methods. High-temperature pulsed arc discharge (HTPAD) is used to synthesize DWNTs with controlled combinations on catalysts of transition metals (Ni/Co/Fe) and rare earth metals (Y/La). The results show that both rare earth metals and cobalt concentrations are crucial to enhance production of DWNTs and to reduce that of residual single-wall carbon nanotubes (SWNTs). The as-produced DWNTs are purified by establishing a dispersion-assisted oxidation procedure. To optimize purification processes, stabilities against oxidation in terms of the number of layers (DWNTs and SWNTs) and of the diameters are investigated. The oxidation rate of DWNTs is twice as low as that of SWNTs with the same diameter of around of 1.6 nm at a suitable temperature. As the results of these optimizations, DWNTs with a purity of 95% have been obtained from as-produced 10% DWNT samples. To achieve this high purification with minimum loss of DWNTs, hybrid oxidation with hot air and refluxing in hydrogen peroxide have been also developed.

High yield synthesis and characterization of the structural and magnetic properties of crystalline ErCl3 nanowires in single-walled carbon nanotube templates

Co-reporter:Ryo Kitaura;Daisuke Ogawa;keita Kobayashi;Takeshi Saito

Nano Research 2008 Volume 1( Issue 2) pp:152-157

Publication Date(Web):2008 August

DOI:10.1007/s12274-008-8013-8

Crystalline ErCl3 nanowires have been fabricated in single-walled carbon nanotubes (SWCNTs) with high yield (∼90%), and the structural and magnetic properties of the resulting ErCl3 nanowires encapsulated in SWCNTs (ErCl3@SWCNTs) characterized. Encapsulation under high temperature and vacuum using high quality SWCNTs results in a high filling-ratio of ErCl3 nanowires in the SWCNTs. The high filling-ratio of ErCl3 nanowires and the use of highly pure SWCNTs with only a small amount of residual Fe catalyst nanoparticles enabled us to observe the magnetic properties of ErCl3@SWCNTs. Structure determination based on simulated annealing calculations and high-resolution transmission electron microscope (HRTEM) image simulations revealed that the structure of the ErCl3 nanowires is unusual with respect to the coordination environment of the Eu3+ ions. This work opens up new possibilities to fabricate various metal complex nanowires with high yield and may also be of more general importance in understanding and exploring magnetic properties in low-dimensional magnetic systems.

Determining exact molar absorbance coefficients of single-wall carbon nanotubes

Co-reporter:Shota Kuwahara, Toshiki Sugai and Hisanori Shinohara

Physical Chemistry Chemical Physics 2009 - vol. 11(Issue 7) pp:NaN1097-1097

Publication Date(Web):2009/01/06

DOI:10.1039/B814008A

Synthesis and UHV-STM observation of the Td-symmetric Lu metallofullerene: Lu2@C76(Td)

Co-reporter:Hisashi Umemoto, Kazunori Ohashi, Takashi Inoue, Nobuyuki Fukui, Toshiki Sugai and Hisanori Shinohara

Chemical Communications 2010 - vol. 46(Issue 31) pp:NaN5655-5655

Publication Date(Web):2010/06/21

DOI:10.1039/C0CC00824A

Transformation of ionic liquid into carbon nanotubes in confined nanospace

Co-reporter:Shimou Chen, Hong En Lim, Yasumitsu Miyata, Ryo Kitaura, Yoshio Bando, Dmitri Golberg and Hisanori Shinohara