Danubia NanoTech, s.r.o. Research in science and technology
Properties of Graphite Oxide, Carbon Nanotubes and their Composite Effect of Irradiation
Viera Skákalová
2001-2011 2011- ????
Max Planck Institute for Solid State Research University of Vienna Stuttgart Collaboratations
Danubia NanoTech, s.r.o. Research in science and technology
Sample preparation, characterization: TEM, modelling: Viliam Vretenár Jannik Meyer Martin Hulman Franz Eder Peter Kotrusz Jani Kotakoski Marcel Meško
Max Planck Institute, Stuttgart Hungarian Academy of Sciences:
Electronic transport: Ion irradiation: Dong Su Lee Zsolt E. Horvath Hye Jin Park Laszlo P. Biro
Different modifications of carbon Danubia NanoTech, s.r.o. Research in nanoscience and nanotechnology
• Production of Single Wall Carbon Nanotubes
• Research on SWNT
• Production of Few-Layer Graphene
• Research on Graphene Defects in SWNTs Raman specroscopy - inelastic photon scattering
G
D* RBM Raman Intensity (a.u.)
0 500 1000 1500 2000 2500 3000 Raman shift (cm-1) D-mode of Raman spectra increases with the Dose of Ar+ ions
D-mode 632 nm pristine 6 D-mode 632 nm 4.0x1012 ions/cm2 pristine 2 12 5 5.0x10 4.0x1011 ions/cm 2ions/cm2 12 2 1.0x10 4.0x10 ions/cm12 ions/cm2 2.0x1012ions/cm2 4
1 3 D
2 IntensityIntensityIntensityIntensity (a.u.) (a.u.) (a.u.) (a.u.)
Intensity (a.u.) 0 1 1200 1300 1400 Wavenumber (cm-1) 0 500 1000 1500 2000 2500 3000 Wavenumber (cm-1) SWNT paper irradiated by 23 MeV C4+ ions
ions Greater damage at the REAR side 8 Back side Irradiated side 6 o )/I o 4 -I
d (I
2 D‐mode
0 0 5 10 15 20 25 30 Dose (1013 ion/cm2)
Skakalova, Kaiser, Detlaff, Arstila, Krashenninikov, Keinonen, Roth: Physica Status Solidi B, 245, (2008) 2280‐2283 C4+‐irradiation of SWNT paper: Electrical conductivity
C4+-energy = 23 MeV
400 Quasi-1D metal C4+ energy = 23 MeV 0 300 300 T = 300K 1. 1014 ion/cm2 200 200 3 10 100 100 30 Conductivity (S/cm) Conductivity (S/cm) 0 Variable-range hopping 0 102030 0 100 200 300 2 Temperature (K) Dose (ion/cm ) Electrical conductance of Ar+ irradiated thin SWNT networks
ions
1.2 +
o Ar energy = 30 keV
0.8
G(Dose)/G 0.4
0.0 0510 Dose (1012 ion/cm2)
1/(1d ) T Variable‐Range Hopping: ()T exp 0 0 T Surface penetration by 30 keV Ar+ ions
ions
Dose effects of 30 keV Ar+ ions
+ 8 0.2 Ar energy = 30 keV o
6 ]/G o
o 0.1 )/I o
-I 4 d
(I 0.0 D-mode 2 [G(Dose)-G -0.1 0 0 5 10 15 20 25 0 5 10 15 20 25 12 2 Dose (1012 ion/cm2) Dose (10 ion/cm )
V. Skakalova, A.B. Kaiser, Z. Osvath, G. Vertesy, L.P. Biro, S. Roth, Appl. Phys. A 90, 597–602 (2008) Effect of thermal annealing: Recovering structure of SWNTs
Pristine Irradiated Annealed
IntensityIntensityIntensity D
1100 1200 1300 1400 Wavenumber (cm-1)
Viera Skákalová, Janina Maultzsch, Zoltán Osváth, László P. Biró, and Siegmar Roth, Phys. Stat. Sol. (RRL) 1, No. 4, 138– 140 (2007) Defects in Graphene Hexagonal crystal structure of graphene
Two equivalent sub‐lattices A and B TEM study of electron irradiation: 12C vs 13C Direct knock-on damage: Energy = 95 keV, Dose of 1.4 x 109 e/nm2 12C 13C no damage
Damage induced by contamination
initial after exposure
Jannik C. Meyer, et al. , PHYSICAL REVIEW LETTER 108, 196102 (2012) Measured and calculated knock-on displacement cross sections.
Monovacancy: dangling bond with a much lower emission threshold. Subsequent sputtering of this atom may double the cross section.
The lower boundary of the shaded areas correspond to the calculated cross section.
The upper boundary is twice the calculated value (expected for correlated sputtering).
Jannik C. Meyer, et al. , PHYSICAL REVIEW LETTER 108, 196102 (2012) Temperature dependences of conductance
Ni‐ A few layers catalyst
2 nm
Cu-catalyst A monolayers
Monocrystal
1 nm Defects formed in presence of ammonia
1 nm 1. pristine CVD‐monolayer 2. N‐doped CVD‐monolayer
-5 10 1
10-6 D 2 2D Sheet conductance (S) Sheet conductance Sheet conductance (S) Sheet conductance 10-7 10 100 Temperature (K) G
H. J. Park, V. Skákalová, T. Iwasaki, J. C. Meyer, U. Kaiser and S. Roth, Physica Status Solidi B, 247(2010)2915‐2919 Chemical Oxidation‐Reduction of Graphite
Graphite oxide was first prepared by Oxford chemist Benjamin C. Brodie in 1859
Oxidation introduces functional groups:
A: Epoxy bridges B: Hydroxyl groups C: Pairwise carboxyl groups
Reduction removes functional groups - Restores sp2 orbitals - Leaves many structural defects Microscopic characterization of thermally reduced Graphite Oxide (rGO)
SEM of GO flakes (Hummers)
STEM of reduced GO Spectroscopic characterization of thermally reduced Graphite Oxide (rGO)
Raman spectra GO GO reduced GO reduced GO 1.0 1.0 1.0 1 nm
0.5 0.5 0.5 Intensity (norm. to G-mode) Intensity (norm. to G-mode) Intensity (norm. to 0.0 0.0 G-mode) Intensity (norm. to 0.0 500 1000 1500 2000 2500500 3000 1000 3500 1500 2000 2500500 3000 1000 3500 1500 2000 2500 3000 3500 -1 -1 -1 Wavenumber (cm ) Wavenumber (cm ) Wavenumber (cm ) X‐ray Photo‐electron Spectra Thorough removal of oxide groups Microscopic characterization of thermally reduced Graphite Oxide (rGO) HR TEM: Jannik Meyer, Uni Ulm Electrical conductivity of thermally reduced Graphite Oxide (rGO) In comparison with SWNT and SWNT‐GO composite
200 rGO 180 180 160
140 160
120
100 SWNT Conductivity (S/cm) Conductivity (S/cm) Conductivity (S/cm) 140 SWNT-GO RGOrGO 80 100100 Temperature (K) SWNT‐GO
• The electrical conductivity of SWNT‐GO composite higher than that of SWNT • Identical electron transport mechanism (Fluctuation Assisted Tunnelling) in SWNT‐GO composite and SWNT paper • Very high electrical conductivity in rGO film with metallic electron transport Summary
SWNT networks:
‐ Ion irradiation damages the structure and lowers electrical conductivity ‐ Thermal annealing removes defects in the SWNT structure
Graphene: A structural damage affects severaly electronic transport
Graphite oxide: Non conductive and transparent. Electrical and optical properties tunable by reduction of the oxide groups.
Reduced graphite oxide: Metallic character of electron transport
Composite SWNT‐GO: The same mechanism of electron transport like in SWNT film
Composite SWNT‐reduced GO: ??????????????? Under investigation. Aknowledgment
The results have been acquired within several years of collaboration between
Max Planck Institute in Stuttgart
Danubia NanoTech (SME) in Bratislava
and
University of Vienna
Thanks for attention
SWNT networks
) 1
S 10
( Buckypaper
100
10-1
10-2 Net 4 Net 3 -3 Net 2 Sheet Conductance Conductance Sheet 10 Net 1 0 20406080100
Transmittance (%)