Carbon Nanostructures

Metal Catalyst Synthesis

Three-dimensional plot showing the mean diameter dependence on oven temperature and Ni/Co ratio. (b) Twodimensional plot of mean diameter vs oven temperature for pure Ni (lower sigmoid curve), pure Co (linear curve), and Ni/Co (1:1) (upper sigmoid curve). (c) Three-dimensional plot of relative yield against oven temperature and Ni/Co ratio. (d) Twodimensional plot of relative yield. From bottom up: pure Co, pure Ni, Ni/Co (1:1). (e) Four-dimensional plot of G/D ratio dependence on catalyst Ni/Co ratio and oven temperature. The shading corresponds to yield. (f) Two-dimensional plot illustrating the G/D change with temperature and catalyst ratio. From bottom up: pure Co, pure Ni, Ni/Co (1:1). Curves are a guide to the eye.

(a, c) TEM micrographs of (oxidized) Fe nanoparticles with median diameters of 5 and 10 nm, respectively. (b, d) Corresponding TEM micrographs of CNT grown from these particles. The particle size or CNT diameter distributions are shown as insets.

S. Tetali, M. Zaka, R. Schoenfelder, A. Bachmatiuk, F. Boerrnert, I. Ibrahim, J.H. Lin, G. Cuniberti, J.H. Warner, B. Buechner, M.H. Ruemmeli
Unravelling the mechanisms behind mixed catalysts for the high yield production of single-walled carbon nanotubes, ACS Nano 3 (2009) Nr. 12, S. 3839-3844 URL

M. Bystrzejewski, M.H. Ruemmeli, H. Lange, A. Huczko, P. Baranowski, T. Gemming, T. Pichler
Single-walled carbon nanotubes synthesis: A direct comparison of laser ablation and carbon arc routes, Journal of Nanoscience and Nanotechnology 8 (2008) Nr. 11, S. 1-9

M. Bystrzejewski, R. Schoenfelder, G. Cuniberti, H. Lange, A. Huczko, T. Gemming, T. Pichler, B. Buechner, M. Ruemmeli
Exposing multiple roles of H₂O in high-temperature enhanced carbon nanotube synthesis, Chemistry of Materials 20 (2008), S. 6586-6588 URL

F. Schaeffel, C. Kramberger, M.H. Ruemmeli, D. Grimm, E. Mohn, T. Gemming, T. Pichler, B. Rellinghaus, B. Buechner, L. Schultz
Nanoengineered catalyst particles as a key for tailor-made carbon nanotubes, Chemistry of Materials 19 (2007) Nr. 20, S. 5006-5009 URL

M.H. Ruemmeli, M. Loeffler, C. Kramberger, F. Simon, F. Fueloep, O. Jost, R. Schoenfelder, A. Grueneis, T. Gemming, W. Pompe, B. Buechner, T. PichlerIsotope-engineered single-wall carbon nanotubes; A key material for magnetic studies, The Journal of Physical Chemistry C 111 (2007) Nr. 11, S. 4094-4098 URL

M.H. Ruemmeli, C. Kramberger, M. Loeffler, O. Jost, M. Bystrzejewski, A. Grueneis, T. Gemming, W. Pompe, B. Buechner, T. Pichler
Catalyst volume to surface area constraints for nucleating carbon nanotubes, The Journal of Physical Chemistry B 111 (2007) Nr. 28, S. 8234-8241 URL

Ceramic Catalyst Synthesis

TEM images of the carbon nanostructures synthesized in the CVD experiments from the SiC particles: (a) overview image, (b) carbon nanostructure capped tip, (c) carbon nanostructure open end, (d) branch on a nanofiber, (e) junction, (f) branch with SiC particle residing at the junction. Inset: FFT of the cubic SiC particle (200). (g) SiC particle at the root of a carbon nanofiber, (h) higher magnification of the cubic SiC particle in panel g. Inset: FFT of cubic SiC particle (100).

Transmission and scanning electron micrographs providing overviews of the products. (a) TEM showing a few carbon nanofibers and sheets of amorphous carbon produced using a pure ethanol feedstock. (b) Higher magnification TEM providing greater detail on the amorphous carbon sheets. Upper inset: FFT showing rings due to amorphous carbon. Graphitic humps are embedded within as highlighted by the lower inset and show two spots from graphitic carbon. The spots correspond to an interlayer spacing of 3.6 Å. (c) SEM image from a sample prepared using a pristine quartz substrate and an ethanol/triethyl borate mixture as the feedstock. (d and e) TEM and SEM images

A. Bachmatiuk, F. Boerrnert, M. Grobosch, F. Schaeffel, U. Wolff, A. Scott, M. Zaka, J.H. Warner, R. Klingeler, M. Knupfer, B. Buechner, M.H. RuemmeliInvestigating the graphitization mechanism of SiO2 nanoparticles in chemical vapor deposition, ACS Nano 3 (2009) Nr. 12, S. 4098-4104 URL

M. Bystrzejewski, A. Bachmatiuk, J. Thomas, P. Ayala, H.-W. Huebers, T. Gemming, E. Borowiak-Palen, T. Pichler, R.J. Kalenczuk, B. Buechner, M.H. Ruemmeli Boron doped carbon nanotubes via ceramic catalysts, Physica Status Solidi RRL 3 (2009) Nr. 6, S. 193-195 URL

M.H. Ruemmeli, F. Schaeffel, C. Kramberger, T. Gemming, A. Bachmatiuk, R.J. Kalenczuk, B. Rellinghaus, B. Buechner, T. PichlerOxide-driven carbon nanotube growth in supported catalyst CVD, Journal of the American Chemical Society 129 (2007) Nr. 51, S. 15772-15773 URL

Synthesis of Single Wall Carbon Nanotubes by Laser Evaporation

The identification of single wall carbon nanotubes (SWCNT) can certainly be considered as one of the most significant stimulants for research in to nanostructures. This is due to their remarkable electronic and mechanical properties. In turn, this has led to a strong demand of SWCNTs for research and commercial applications. In addition, there is a need to clearly understand the growth mechanisms so as to have control over the electronic properties of SWCNT.

We have several laser ablation systems available to us through our own facilities and jointly with the Technical University Dresden.

TEM image of SWCNT bundle synthesized with a Ni-Co binary catalyst at 1200C.

Relative downshift of the G mode Raman spectra as a function of 13C enrichment. Vertical dotted line indicates the non-shifting G mode.

Areas of interest:

Analysis of the production conditions by laser ablation:
SWCNT yield, mean diameter and diameter distribution as function of temperature, gas, pressure, catalyst particles, laser pulse etc.
Studies on the growth mechanisms:
TEM images of SWCNT bundles synthesized with metal oxide catalysts at low temperature.
Special SWCNT: e.g. ¹³C doped SWCNT for NMR studies
Development of a CO₂ CW laser ablation system.

Selected Papers:

M. H. Rümmeli, C. Kramberger, M. Loeffler, O. Jost, M. Bystrzejewski, A. Gruneis, T. Gemming, W. Pompe, B. Buechner, T. Pichler
Catalyst volume to surface area constraints for nucleating carbon nanotubes, Journal of Physical Chemistry B, 111 (2007) 8234

M. H. Rümmeli, M. Löffler, C. Kramberger, F. Simon, F. Fueloep, O. Jost, R. Schoenfelder, A. Grüneis, T. Gemming, W. Pompe, B. Buechner, T. Pichler,
Isotope-engineered single-wall carbon nanotubes; A key material for magnetic studies, Journal of Physical Chemistry, 111 (2007) 4094

X. Lin, M. H. Rümmeli, T. Gemming, T. Pichler, D. Valentin, G. Ruani, C. Taliani
Single-wall carbon nanotubes prepared with different kinds of NiCo catalysts: Raman and optical spectrum analysis, Carbon 45 (2007) 196

M. H. Rümmeli, E. Borowiak-Palen, T. Gemming, T. Pichler, M. Knupfer, M. Kalbác, L. Dunsch, O. Jost, S. R. P. Silva, W. Pompe, B. Büchner
Novel catalysts, room temperature and the importance of oxygen for the synthesis of single wall carbon nanotubes. Nano Letters, 5, (2005) 1209-1215

Graphene

Example of an etch track in graphite (a) with 45° degree angles; (b) visualization of the 45° angle in graphite. http://www.springerlink.com/content/a71144j62411727j

Direct determination of etch direction from HRTEM: (a) HRTEM micrograph of Co particle at the track front; (b) Fourier enhanced TEM micrograph of the marked area in (a); (c) reconstructed image of the marked area in (b) produced by using a mask applied to the 2-D fast Fourier transform of the image; (d) Schematic view of the graphite lattice defi ning the graphite unit cell (yellow), the crystallographic directions and the zigzag and armchair edges. (Details of the carbon hydrogenation process: 775 °C, 5 min in 60 mbar H2, plus 5 min in vacuum). http://www.springerlink.com/content/a71144j62411727j

(a) HRTEM image of the Moire pattern produced in a bilayer structure. (b) Structural representation of two graphene layers with 30° rotation. (c) Overlay of the structural representation in panel b with the HRTEM image in panel a, showing excellent agreement with the areas of contrast. (d) Schematic diagram illustrating two graphene layers with 30° rotation added together to produce a superstructure. (e) HRTEM image of the superstructure illustrated in panel d. (f) HRTEM image simulation of the superstructure illustrated in panel d and imaged in panel e showing excellent agreement. http://pubs.acs.org/doi/abs/10.1021/nl8025949

M.H. Ruemmeli, C.G. Rocha, F. Ortmann, I. Ibrahim, H. Sevincli, F. Boerrnert, J. Kunstmann, A. Bachmatiuk, M. Poetschke, M. Shiraishi, M. Meyyappan, B. Buechner, S. Roche, G. Cuniberti, Graphene: Piecing it together, Advanced Materials 23 (2011), S. 4471-4490 URL

F. Schaeffel, M. Wilson, A. Bachmatiuk, M.H. Ruemmeli, U. Queitsch, B. Rellinghaus, G.A.D. Briggs, J.W. Warner
Atomic resolution imaging of the edges of catalytically etched suspended few-layer graphene, ACS nano 5 (2011) Nr. 3, S. 1975-1983 URL

A. Scott, A. Dianat, A. Boerrnert, A. Bachmatiuk, S. Zhang, J.H. Warner, E. Borowiak-Palen, M. Knupfer, B. Buechner, G. Cuniberti, M.H. Ruemmeli
The catalytic potential of high-k dielectrics for graphene formation, Applied Physics Letters 98 (2011) Nr. 7, S. 73110/1-3

J.H. Warner, M.H. Ruemmeli, A. Bachmatiuk, B. Buechner
Examining the stability of folded graphene edges against electron beam induced sputtering with atomic resolution, Nanotechnology 21 (2010) Nr. 32, S. 325702/1-6 URL

M.H. Ruemmeli, A. Bachmatiuk, A. Scott, F. Boerrnert, J.H. Warner, V. Hoffman, J.-H. Lin, G. Cuniberti, B. Buechner
Direct low-temperature nanographene CVD synthesis over a dielectric insulator, ACS Nano 4 (2010) Nr. 7, S. 4206-42 URL

J.H. Warner, M.H. Ruemmeli, L. Ge, T. Gemming, B. Montanari, N.M. Harrison, B. Buechner, G.A.D. Briggs
Structural transformations in graphene studied with high spatial and temporal resolution, Nature Nanotechnology 4 (2009) Nr. 8, S. 500-504

J.H. Warner, M.H. Ruemmeli, T. Gemming, B. Buechner, G.A.D. Briggs
Direct imaging of rotational stacking faults in few layer graphene, Nano Letters 9 (2009) Nr. 1, S. 102-106 URL

F. Schaeffel, J.H. Warner, A. Bachmatiuk, B. Rellinghaus, B. Buechner, L. Schultz, M.H. Ruemmeli
Shedding light on the crystallographic etching of multi-layer graphene at the atomic scale, Nano Research 2 (2009), S. 695-705 URL

M.H. Ruemmeli, C. Kramberger, A. Grueneis, A. Ayala, T. Gemming, B. Buechner, T. Pichler
On the graphitization nature of oxides for the formation of carbon nanostructures, Chemistry of Materials 19 (2007) Nr. 17, S. 4105-4107 URL