FK - 5th International Conference
Novel Functional Carbon Nanomaterials

Session FK-1 - Growth and Processing

FK-1:IL01  Graphene Growth and Integration in Nanoelectronic Devices
L. COLOMBO¹, Y. HAO², S. MCDONNELL³, R. ADDOU³, A. ISMACH², A. AZCATL³, S.S. SONDE², S. BANERJEE², R.S. RUOFF², R.M. WALLACE³, ¹Texas Instruments, Dallas, TX, USA; ²University of Texas at Austin, Austin, TX, USA; ³University of Texas at Dallas, Dallas, TX, USA

In the past decade, the state-of-the art Si-based electronics has gone from devices above 100 nm to the realm of 20 nm and below. As devices have scaled below a gate length of 100nm the performance per power density has not scaled. In order to address the power issues the industry is facing as CMOS devices are scaled, in addition to the introduction of high-k, metal gates, and FinFETs, new materials and devices that take advantage of new state variables to improve performance per power density will have to be studied. Graphene has been the subject of considerable theoretical and experimental interest because of its unique physical properties. New devices taking advantage of the theoretical prediction on the existence of a Bose-Einstein condensate in bi-layer graphene films, graphene based tunnel FETs, Veselago lens based devices, and all spin logic devices have been proposed. In order to demonstrate that any of the proposed can meet the basic device requirements, high quality films will have to be developed and integrated with dielectrics and metal contacts. In this presentation we will review the need for devices beyond CMOS, growth of polycrystalline and single crystal graphene, and integration of dielectrics and metal contacts and their effects on FET characteristics.


FK-1:IL02  Science and Applications of Doped Nanocrystalline Diamond Films and Particles
K. HAENEN, Hasselt University, Institute for Materials Research (IMO) & IMEC vzw, IMOMEC, Diepenbeek, Belgium

Nanocrystalline diamond (NCD) is a versatile, granular material usually deposited in the form of a thin film using plasma enhanced chemical vapour deposition (CVD) techniques. While more traditional applications, such as wear resistant coatings, make use of undoped films, most of the currently envisaged applications are based on electrically conductive, doped material.
The first part of this presentation will focus on fundamental aspects of the three main dopant atoms incorporated through in-situ doping during the growth: boron, nitrogen, and phosphorus. The granular nature of the material, partly influenced by the deposition conditions, will greatly influence dopant incorporation, location, bonding structure, and distribution. In turn, such aspects will become evident in several basic properties, including electrical transport, which will be treated in detail.
Then a selection of applications based on doped films will be discussed. These include heavily B-doped membranes acting as beam monitors and piezoresistive elements, and thermionic emitters based on P-doped films.
Finally, to conclude, the use of thick, microcrystalline films as a starting material for the fabrication of doped nanoparticles, their subsequent characterisation, and possible use will be considered.


FK-1:IL03  Oriented Attachment Growth of Micro-sized Diamond Crystals from Detonation Nanodiamonds
F.M. SHAKHOV, S.V. KIDALOV, P.G. BARANOV, R.A. BABUNTS, D.A. SAKSEEV, D.A. KIRILENKO, A.E. ALEKSENSKII, M.V. BAIDAKOVA, A.YA. VUL', Ioffe Institute, Saint-Petersburg, Russia

We have submitted experimental evidences on formation diamond single crystals (SC) ranging from 50 nm to 1 micron at HPHT sintering of detonation nanodiamonds (DND) particles with grain size of 4 nm. The SC are formed in the thermodynamic stability region of diamond without any metal catalyst.
Results of SEM, TEM, EELS, Raman scattering allow us to conclude that the oriented attachment growth (OAG) mechanism [1] is responsible for the crystals growth. Boundaries between initial 4 nm grains in the crystals are either fully coherent or have only single defects localized in 1-3 carbon layers with sp3-hybridization.
The OAG was known only for oxide systems [1], however we have recently found that X-ray coherent scattering region of DND particles was increased at HPHT sintering [2-4] and that fact can be also related to the OAG. Possibility of OAG diamond SC from DND open a new way for synthesis of perfect micro-sized diamonds with desirable concentration of impurities and defects.
This study was supported by the RFBR (12-02-00108-a), Min. Ed. Sci. (8017, 8568).
1. Q. Zhang et al. J. Mater. Chem. 19(2009) 191-207.
2. S.V. Kidalov et al. Diam. Relat. Mater. 19(2010) 976-980.
3. S.V. Kidalov et al. Materials. 2(2009) 2467-2495.
4. S.V. Kidalov et al. Cryst. Rep. 56(7)(2011) 1181-1185.


FK-1:IL04  Large Scale Growth of Graphene on SiC
R. YAKIMOVA^{1, 2}, G.R. YAZDI¹, T. IAKIMOV^{1, 2}, V. DARAKCHIEVA¹, ¹Linkoping University, Linkoping, Swede; ²Graphensic AB, Sweden

The main advantage of graphene grown on silicon carbide (SiC) substrates is that no transfer is needed for device processing. Also the size of the graphene sheet can be as large as the substrate, which presently reaches 150 mm in diameter. We are fabricating epitaxial graphene on SiC substrates by using high temperature sublimation process. We have demonstrated large area monolayer graphene that can be used as resistance standard in quantum metrology. However some challenges are still in place. An important issue in this type of graphene is that its electronic properties are to a large extent substrate mediated. Therefore the effect of the surface uniformity and morphological stability of the grown graphene monolayers are of a primary significance.
Here we report surface features of epitaxial graphene on different SiC substrates and how the large scale yield depends on that. Graphene formations has been studied in respect to step bunching and surface decomposition energy differences created by the SiC basal plane stacking sequence in different SiC polytypes.
It was observed that the step distance is a dominating factor in the unintentional buffer layer induced doping of graphene due to SiC substrate. Studies by AFM, LEEM, ARPES, and spectroscopic ellipsometry are reported.


FK-1:IL05  Synthesis & Assembly of Chemically Modified Graphitic Carbon Nanostructures
SANG OUK KIM, Center for Nanomaterials and Chemical Reactions, Institute for Basic Science (IBS) Materials Science & Engineering, KAIST Daejeon, Republic of Korea

Graphitic carbons, such as carbon nanotubes and graphene, have outstanding material properties, including high electrical conductivity, superior mechanical properties, extremely large surface area and mechanical flexibility. Directed assembly of those graphitic carbons into desired architectures is crucial for many potential applications. In this presentation, our recent progress in the tailored assembly of carbon nanotubes and graphene will be introduced. Graphitic carbons can be assembled into various three dimensional structures via solvent dispersion. Directed growth from nanopatterned catalyst array enables precise control of the morphology and properties of graphitic materials as well as their assembly. In addition, aforementioned two approaches can be synergistically integrated to generate carbon hybrid assembly consisting of vertical carbon nanotubes grown on flexible graphene films. We will also present tailored assembly in conjunction with optimized chemical modification and doping, which may enable the ultimate utilization of graphitic carbon materials in optoelectronics, nanocomposites, energy storage/conversion, and so forth.


FK-1:IL07  Graphene Nanopatterning with Nanometer Precision and Edge Orientation Control
L. TAPASZTO,  Research Centre for Natural Sciences, Institute of Technical Physics and Materials Science, Budapest, Hungary

The electronic properties of graphene nanostructures are predicted to fundamentally depend both on their size and the crystallographic orientation of the edges. However, no systematic experimental data is available so far regarding the effect of edge orientation on the electronic properties of graphene nanostructures. This is due to the fact that previous studies have been mainly conducted on graphene nanostructures fabricated with no control over the edge orientation. Here, we present a nanopatterning method, which employs a Scanning Tunneling Microscope to define graphene nanostructures with (sub-) nanometer precision and predefined crystallographic edge orientation. We have systematically investigated the electronic structure of the as-created graphene nanoribbons. We found that in the sub-10 nm regime a band gap can open in both armchair and zigzag ribbons, but the scaling and the underlying mechanisms are fundamentally different for the two cases.


FK-1:IL08  Growth of Large-size Single-crystal Graphene Domains and Three-dimensional Interconnected Graphene Networks
WENCAI REN, LIBO GAO,TENG MA, ZONGPING CHEN, HUI-MING CHENG, Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang, P.R. China

The controlled growth of graphene is highly important for its various applications. Firstly, we have realized the growth of millimeter-size hexagonal single-crystal graphene domains and graphene films joint from such domains on Pt substrates by ambient-pressure chemical vapor deposition (CVD) [1]. Moreover, we proposed a bubbling method to transfer these single graphene grains and graphene films to arbitrary substrate, which is nondestructive not only to the graphene but also to the Pt substrates [1]. These single-crystal graphene obtained shows high crystal quality with a carrier mobility greater than 7,000 cm2V-1s-1 under ambient conditions. In addition, we studied the growth kinetics of single-crystal graphene domains during a CVD growth-etching-regrowth process [2]. We found that the graphene edges and morphology are not determined by the nucleation but are kinetically controlled during the CVD process and that defects in the graphene can be healed through an etching-regrowth process. More importantly, we observed that both the growth and etching rates of a single-crystal graphene domain increase linearly with the slanted angle of its edges from 0 to ~19°. Such phenomena were well explained based on the density functional theory calculations and classical kinetic Wulff construction theory. Using these findings, we also proposed several strategies for the fabrication of wafer-sized, high-quality, single-crystal graphene, which opens up the possibilities for the use of graphene in electronics and optoelectronics. Secondly, we have realized the direct synthesis of three-dimensional interconnected graphene networks by template-directed CVD, which we call graphene foam (GF) [3]. The GF has fast transport channel of charge carriers for high electrical conductivity. Moreover, it is extremely light, flexible and has very high porosity and specific surface area. The unique network structure and combined outstanding properties of GFs greatly expand the applications of graphene. For example, we have demonstrated the use of this material for elastic conductors [3], high-sensitivity gas sensors [4], flexible lithium ion batteries with ultrafast charge and discharge rates [5], and lightweight and flexible high-performance electromagnetic interference shielding materials [6].
References:
[1] L.B. Gao, W.C. Ren, H.L. Xu, L. Jin, Z.X. Wang, T. Ma, L.P. Ma, Z.Y. Zhang, Q. Fu, L.M. Peng, X.H. Bao, H.M Cheng, Nature Communications, 3 (2012) 699.
[2] T. Ma, W.C. Ren, X.Y. Zhang, Z.B. Liu, Y. Gao, L.C. Yin, X.L. Ma, F. Ding, H.M. Cheng, PNAS, 2013, Accepted.
[3] Z.P. Chen, W.C. Ren, L.B. Gao, B.L. Liu, S.F. Pei, H.M. Cheng, Nature Materials 10 (2011) 424.
[4] F. Yavari, Z.P. Chen, A.V. Thomas, W.C. Ren, H.M. Cheng, N. Koratkar, Scientific Reports 1 (2011) 166.
[5] N. Li, Z.P. Chen, W.C. Ren, F. Li, H.M. Cheng, PNAS, 109 (2012) 17360.
[6] Z.P. Chen, C. Xu, C.Q. Ma, W.C. Ren, H.M. Cheng, Advanced Materials, 25 (2013) 1296.


FK-1:IL09  What Would be the First Industrial Scale Application of Single-walled Carbon Nanotubes and Why?
KENJI HATA, AIST, Tsukuba, Japan

For over two decades CNT`s and single-walled carbon nanotubes (SWNT) have been extensively researched, as evidenced by the over 10,000 papers published each year. However CNT are not yet a material used heavily in industry, particularly for SWNT`s still only research grade material is available. I envision that this situation is going to change quickly, since the first industrial scale SWNT production plant is planned to be in operation in 2015. At the same time, a couple of SWNT applications would hit the market. These "first" SWNT industrial applications are going to be very different from what we researchers had thought they would be useful for. It is interesting to note that most of the developed applications do not even care much of the electrical or thermal properties of the SWNTs.
In this talk I would briefly overview our efforts to develop the first industrial scale SWNT production plant based on the super-growth CVD, and present what I envision would be the first industrial scale application of SWNT applications, and more importantly why?


FK-1:IL10  Hierarchical Nanoporous Carbon Materials for Supercpacitors and Lithium Sulfur Batteries
S. KASKEL, Dresden University of Technology, and Fraunhofer IWS, Germany

Metal- or semi-metal atoms can be selectively removed from their carbides in the presence of halogens such as chlorine gas at high temperatures. This etching reaction produces a highly microporous (d < 2 nm) carbon network known as carbide-derived carbon (CDC). The size distributions of CDC micropores are rather narrow as compared to other porous carbon materials, such as physically or chemically activated carbons. This makes CDCs highly suitable for applications in gas storage, separation or as electrode materials in supercapacitors.
In the last years we reported various approaches for the generation of CDCs with hierarchical pore architectures starting from polycarbosilanes as SiC precursors to generate porous carbon materials with bi- or trimodal pore size distributions for applications in supercaps and Li-S-batteries. In the present contribution an overview about strategies for pore design in electrode materials applications will be given with specific capacities significantly exceeding a value of 240 F/g in aqueous electrolyte. Furthermore, extremely high reversible capacities of more than 800 mAh/g (related to the mass of the active material) and outstanding cycling performance were determined for the large-pore CDCs as a cathode material in lithium-sulfur cells.


FK-1:IL11  Insights in the Synthesis of Carbon Nanostructures from Computer Simulation
C. BICHARA, M. DIARRA, CINaM, CNRS and Aix Marseille University, France; H. AMARA, F. DUCASTELLE, LEM, ONERA and CNRS, Chatillon, France

The outstanding physical properties of novel carbon-based materials (nanotubes, graphene …) strongly depend on their structure: chirality for SWNTs, number of layers and stacking for graphene. However, materials produced are far from being ideal and a detailed atomic scale understanding of the nucleation and growth of SWNT and graphene, as provided by computer simulation, is still highly desirable. We use a carefully assessed tight binding model for nickel and carbon [1-3] to numerically investigate different aspects of the CCVD synthesis. We study the chemical and physical states of the metal catalyst as a function of size, temperature and carbon chemical potential conditions corresponding to nucleation and growth of SWNTs [4, 5] and graphene [6].
[1] H. Amara et al., Phys. Rev. B 79, 014109 (2009)
[2] J. H. Los et al., Phys. Rev. B 84, 085455 (2011)
[3] H. Amara et al., Phys. Rev. Lett., 100, 056105 (2008)
[4] M. Diarra et al., Phys. Stat. Sol. B 249, 12, 2629–2634 (2012)
[5] M. Diarra et al., Phys. Rev. Lett. 109, 185501 (2012)
[6] S. Haghighatpanah et al., Phys. Rev. B 85, 205448 (2012)


FK-1:L12  Macro-mesoporous Nanocarbon Thin Films. Processing and Application to Energy Storage
M. ES-SOUNI, D. SHOPF, Institute for Materials & Surface Technology, University of Applied Sciences, Kiel, Germany

Macro-mesoporous thin films of approximately 1µm thickness are processed via controlled pyrolysis of porous PVDF thin films that were deposited on various supports, including metallic substrates. Microscopic and structural characterization show that the films consist of glassy carbon and faceted carbon nanocrystals, and a homogeneous distribution of meso and macropores. Preliminary results on the suitability of these films for supercapacitor applications will be shown, with outstanding specific capacitances for some films that reach up to 180F/g.


FK-1:L13  Designing and Guiding the Synthesis of a New Class of Fullerene-like C-based Nanostructured Compounds
C. GOYENOLA, S. SCHMIDT, S. STAFSTRÖM, L. HULTMAN, G.K. GUEORGUIEV, Department of Physics, Chemistry, and Biology - IFM, Linköping University, Linköping, Sweden

By developing the Density Functional Theory (DFT)-based Synthetic Growth Concept (SGC) understood as structural evolution by sequential steps where each one is defined by the previous relaxed state, we can address structural evolution and growth of inherently nanostructured materials with mostly covalent bonding.
SGC is also the theoretical tool behind designing new low-dimensional and graphene-like systems and assessing their functionalization (e.g., fluorination and hydrogenation of 2D graphene-like systems).
Perceiving the Fullerene-like (FL) solid compounds as an entirely new class of C-based materials, we have employed SGC to better understand structural properties of FL-CNx and to predict the feasibility as well as to successfully guide the synthesis of solid FL-CPx (hard and resilient) thin films.
The purpose of this presentation is to emphasize, within the general context of SGC and its transferability, the growth evolution and the structural/bonding properties of the two newest members of this particular class of nanostructured thin films, namely the Sulpho Carbide (CSx) and the Carbon Fluoride (CFx).
While the CSx thin films can find applications as hard and resilient coatings, the (recently synthesized by us) CFx compound holds promise as a new Teflon-like material.


FK-1:L14  CVD of N-Doped Graphene
H. SACHDEV, Max Planck Institut für Polymerforschung, Mainz, Germany

Thermally induced chemical vapor deposition (CVD) was used to study the formation of nitrogen doped graphene and carbon films on copper from aliphatic nitrogen containing precursors consisting of C1- and C2- units and (hetero) aromatic nitrogen containing ring systems. The structure and quality of the resulting films were correlated to the influence of the functional groups of the precursor molecules and the gas phase composition. The presence of (N-doped) - graphene was confirmed by the 2D mode of the Raman spectra. Precursors with nitrogen functional groups can lead to a direct formation of graphene even without additional hydrogen present in the gas phase. This is not observed for e.g. methane under comparable CVD conditions. Therefore, nitrogen containing gas phase- species can significantly enhance the graphene film growth. Kinetic and thermodynamic effects can be considered for the decay of the precursors.


FK-1:L15  Spectral Tuning of Graphene Quantum Dots by Salting Out
KYUEUI LEE, SEONGWOO RYU, HAESHIN LEE, Departmet of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Republic of Korea; SOON HYUNG HONG, The Graduate School of Nanoscience and Technology (WCU), Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Republic of Korea

In this study, we report a method that can effectively sort GQDs with various dimensions. The method simply utilizes the addition of salts to a heterogeneous mixture of GQD solutions. The purification process is based on differences in dispersibility of individual GQDs as a function of salt concentrations. In fact, we previously reported that the use of a salt can separate graphene oxides with different dimensions (S. Ryu et al. Carbon, 2013, 63, 45-53). Different from the previous study, we found that a salt can distinguish tiny differences in physical properties of GQDs, resulting in the separation of GQDs with narrow windows of physicochemical properties of GQDs. Well-purified GQD subpopulations exhibited GQDs with average diameters of 2.7 ± 1.4 nm, 5.1 ± 1.9 nm, 13.3 ± 3.11 nm, and 18.7 ± 4.44 nm. Consequently, each of GQD subpopulations exhibited blue purple, blue, yellow green and orange emission properties in 325nm excitation condition. These results demonstrate that salts are effective additives in purifying size dependent GQD subpopulations which is entirely new way of spectral tuning.
 
 
Session FK-2 - Structural Characterization

FK-2:IL01  Boron Doping Profiling in Diamond Multilayers by Electron Microscopy
D. ARAUJO¹, M.P. ALEGRE¹, J.C. PIÑERO¹, P. VILLAR¹, A. FIORI², E. BUSTARRET², ¹Dpto. Ciencia de los Materiales e IM y QI, Universidad de Cádiz, Puerto Real (Cádiz), Spain; ²Institut Néel, CNRS-Université Joseph Fourier, Grenoble, France

The development of diamond based HEMTs is oriented to high power applications and should also allow a potential improvement of the device velocity. Among the different possible architectures, d-doped structures designs are focused on allowing a delocalization of the carriers to improve their mobility. To obtain such diamond related electronic devices, an accurate control of the spatial location of the dopant should be realized down to the nanometer scale.
From this standpoint, transmission electron microscopy (TEM), in diffraction contrast mode or using the high angle annular dark field detector (HAADF) in the TEM scanning mode (STEM) has revealed to be sensitive to boron doping. A quantification of this signal is here presented.
The first method use the intensity recorded at two different reflexions in dark field mode. Using the Howie-Wealand equations for the diffracted intensity of the 004 and 220 beams, thickness of the TEM lamella preparation and boron-content are deduced fitting, through an iterative method, experimentally measured intensities. In the second method, boron doping profiles are also deduced by fitting a simple modelization of the HAADF-STEM signal, but here a pre-calibration of the detector is necessary to obtain the boron content. The methods are applied to diamond d-doped layers. The actual measured δ-doped layers are below 5nm with a doping level of 10²¹cm^-3, which is very close to requirements for carrier delocalization.


FK-2:IL02  Characterization of Diamond-molecular Interfaces by Advanced SPM
B. REZEK, Institute of Physics ASCR, Prague, Czech Republic

Diamond provides a unique combination of suitable semiconducting, mechanical, and chemical properties for biomedical applications [Biosens.Bioelectron.26(2010)1307] as well as for energy conversion and storage systems [Nanoscale Res.Lett.6(2011)238]. Attachment of various molecular species to diamond surface is fundamental for these applications [J.Phys.D40(2007)6443]. However, characterization of such all-carbon systems is often complicated. Here we show that advanced regimes of atomic and Kelvin force microscopy (AFM/KFM) provide crucial data for understanding properties of diamond-molecular interfaces in various forms. We characterize structural and electronic interactions of diamond with organic materials in air and solutions representing application-relevant environments. We show how to discriminate physisorption and chemisorption of organic molecules (DNA, proteins, organic dyes) to diamond by AFM, KFM and scanning electron microscopy (SEM) [Int.J.Electrochem.Sci.8(2013)17]. We also elucidate stability and functions of diamond-organic interfaces in terms of switching molecular conformations, change of surface electronic equilibrium, and photovoltage.


FK-2:IL03  Extended Defects in 2D-materials: Graphene, MoS2 and Silica Bilayers
A.V. KRASHENINNIKOV^{1, 2}, H.-P. KOMSA¹, S. KURASCH³, J. KOTAKOSKI^{1, 4}, O. LEHTINEN^{1, 3}, U. KAISER³, ¹Department of Physics, University of Helsinki, Finland; ²Department of Applied Physics, Aalto University, Finland; ³Central Facility for Electron Microscopy, Group of Electron Microscopy of Materials Science, Ulm University, Ulm, Germany; ⁴Department of Physics, University of Vienna, Austria

Line defects, like dislocations, govern the mechanical properties of any material. They can also affect strongly material electronic characteristics. By combining high-resolution transmission electron microscopy experiments and first-principles calculations, we study the formation and evolution of line defects in graphene, [1,2] MoS2 [3,4] and bilayer silica. In graphene, we observed the full life cycle of a dislocation from birth to annihilation [2]. As for MoS2, different kinds of extended defects which appeared due to vacancy agglomeration are distinguished in the experiments, and their atomic structures and electronic properties are determined with the help of calculations. Our calculations also indicate that the electronic properties of the extended defects can be tuned by filling vacancy lines with other atomic species, thereby suggesting a way for strain and electron- beam-assisted engineering of MoS2-based nanostructures. Finally, we discuss line defects in 2D silica bilayers [5] and compare them to graphene, another 2D material with the same hexagonal symmetry.
1. S. Kurasch et al., Nano Letters 12 (2012) 3168.
2. O. Lehtinen et al. Nature Comm. 4 (2013) 2098.
3. H. Komsa et al., PRL 109 (2012) 035503.
4. H. Komsa et al. B 88 (2013) 035301.
5. P. Y. Huang, Nano Letters


FK-2:IL04  Kelvin Force Microscopy on Graphene
W. MERTIN, C. ALVARADO, G. BACHER, Universität Duisburg-Essen, Duisburg, Germany

Graphene is a promising candidate for electronic and optoelectronic applications because of its high electrical conductivity and optical transparency. However, non-pristine graphene suffers from inhomogeneous electronic properties due to e.g. grain boundaries, cracks, wrinkles, functional groups or lattice defects. Kelvin Probe Force Microscopy (KPFM) is an attractive technique to locally correlate electronic and structural properties of graphene devices with nanometer scale resolution.
Here, we demonstrate the potential of KPFM measurements on functionalized graphene sheets (FGS) made by thermal exfoliation and of CVD-graphene in a two and a three terminal device architecture, respectively. Our measurements allow a new insight into the intrinsic conductivity, the nature of the charge transport between graphene and metal contacts and the correlations between electrical properties and topographic or structural features. In a transistor made of CVD graphene, the voltage drop at the contacts can be clearly separated from the intrinsic resistivity and the change of the conducting graphene channel via gate voltage can be directly visualized. By locally recording contact and sheet resistance in FGS via KPFM, we can identify the change of the transport mechanism from hopping to diffusive transport going along with a change from a Schottky-type contact to a nearly non-invasive metal-metal contact characteristics if the C/O ratio is varied.


FK-2:IL05  Atomic Imaging and Spectroscopy of Two-dimensional Carbon and Non-carbon Materials
K. SUENAGA, Nanotube Research Center, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki, Japan

Atomic defects or edge structures are of great importance especially in the wide range of researches for any kind of low-dimensional materials, since the interrupted periodicities strongly affect their physical and/or chemical properties. After a monovacancy was first observed by TEM and proved to be stable even in low-dimensional carbon structures [1], studies of point defects in mono-layered materials have become very popular among scientists. Vacancies and topological defects in graphene are routinely examined at atomic level [2, 3]. Defects and edge structures in hexagonal boron nitride (h-BN) and WS2 nano-ribbons are also a hot topic among physicists [4, 5].
Here we describe TEM and spatially resolved EELS studies of various single-layered materials with the interrupted periodicities. Atomic defects and edge structures can be unambiguously identified with the elemental assignment. The monovacancy analysis in h-BN single-layer [6] and the alloying and doping behaviors of MoS2/WS2 single-layers [7] will be presented.
[1] A. Hashimoto et al., Nature, 430 (2004) pp.870-873
[2] K. Suenaga et al., Nature Nanotech., 2 (2007) pp.358-360
[3] K. Suenaga and M. Koshino, Nature 468, 1088-1090 (2010).
[4] C. Jin et al., Phys. Rev. Lett., 102, 195505 (2009)
[5] Z. Liu et al., Naure Commun. 2, 213 (2011).
[6] K. Suenaga, H. Kobayashi, and M. Koshino, Phys. Rev. Lett., 108 075501 (2012).
[7] D. Dumcenco, H. Kobayashi, Z. Liu, Y.-S. Huang and K. Suenaga, Nature Commun. 4 1351 (2013).
[8] The work is partially supported by JST Research Acceleration Programme.


FK-2:IL06  Time-resolved Optoelectronic Characterization of Graphene-based Nanoscale Circuits
A. HOLLEITNER, Walter Schottky Institut and Physik-Department, Technische Universität München, Garching, Germany

We introduce a THz-time domain photocurrent spectroscopy to graphene with a picosecond time-resolution [1], and demonstrate that THz-radiation is generated in optically pumped, freely suspended graphene. The electro-magnetic radiation is detected by a coplanar metal stripline which acts as a highly sensitive near-field antenna and waveguide with a bandwidth of up to 1 THz. Our ultrafast photocurrent experiments further clarify the optoelectronic mechanisms contributing to the photocurrent generation at graphene-metal interfaces. So far, this photocurrent has been extensively investigated by spatially resolved, but time-integrated photocurrent imaging techniques. We verify that both built-in electric fields, similar to those in semiconductor-metal interfaces, and a photothermoelectric effect give rise to the photocurrent at graphene-metal interfaces at different picosecond time scales. Furthermore, recent fluorescent experiments have demonstrated that the fluorescence of nitrogen vacancy centers in diamond is quenched by the presence of graphene. We present corresponding time-resolved optoelectronic measurements on Förster Resonant Energy Transfer (FRET) processes in graphene-based hybrid devices [2].
[1] L. Prechtel et al. Nature Comm. 3, 646 (2012).
[2] A. Brenneis et al. (2014)


FK-2:IL07  Growth, Structure, and Properties of Carbon Nanomaterials Studied by In-situ Electron Microscopy
F. BANHART, O. CRETU, J.A. RODRIGUEZ-MANZO, Institut de Physique et Chimie des Matériaux de Strasbourg, UMR 7504, Université de Strasbourg, CNRS, Strasbourg, France

The talk will present an overview of recent in-situ experiments on carbon nanomaterials in the specimen chambers of transmission electron microscopes. Different techniques for in-situ experimentation are described such as heating, irradiation, or electrical probing of carbon structures under observation. The focus will be on one- and two-dimensional carbon nanomaterials such as monoatomic carbon chains and graphene. Dynamic phenomena are accessible to direct observation such as the nucleation and growth of graphene or carbon nanotubes, the diffusion of metal atoms on graphene, the formation of chains of carbon atoms, or the interaction between energetic electrons and graphitic nanomaterials. The formation of lattice defects by electron irradiation is a further subject of in-situ TEM as it allows the observation of lattice reconstruction after ballistic atom displacements. Irradiation effects can also be used to tailor the structure and properties of specific nanomaterials and for joining different species as will be shown for the example of metal-carbon junctions. In-situ electrical probing by an STM tip allows us to generate chains of carbon atoms and to measure their electrical properties for the first time.


FK-2:IL09  X-ray Diffraction and Small Angle X-ray Scattering for Characterization of Carbon Nanostructures
M.V. BAIDAKOVA, A.T. DIDEIKIN, A. YA. VUL, Ioffe Physical-Technical Institute, St. Petersburg, Russia

Diffraction essentially involves a study of the angular distribution of the scattering intensity by the material of interest of radiation, for example, X-ray (including synchrotron) radiation, neutron flux and etc.
Most of the methods employed in diffraction data treatment were developed for conventional crystalline materials, assuming infinite long-range order in the sample under study. For carbon nanostructures (CNs) - objects that are only a few nan ometers in size, however, we can no longer assume long-range ordering because of the limited size of the nanocrystal. Also using standard methods of small-angle scattering data treatment assuming CNs to have uniform structure may produce wrong results and conclusions. However, bearing in mind the above constraints on the applicability of these methods, they can be employed to characterize a series of samples to reveal trends in the variation of a parameter of interest initiated by an external action (e.g., temperature, pressure) [1]. The results obtained by these methods in studies of nonocrystalline diamond are presented.
[1] Alexander Vul', Marina Baidakova, and Artur Dideikin «Nanocrystalline Diamond» In: Carbon nanomaterials. Second Edition. CRC Press, Taylor& Francis Group. Ed. Yury Gogotsi & Volker Presser. 2013.


FK-2:IL10  Endohedral Fullerenes: the Importance of Size, Shape and Electronic Complementarity between Encapsulated Clusters and Cages
L. ECHEGOYEN, University of Texas-El Paso, El-Paso, TX, USA

We recently discovered a new and very large family of endohedral compounds containing dimetallic sulfide as the encapsulated cluster, M2S@C2n, with cages ranging from C70 to C100. The X-Ray single crystal of Sc2S@C82 (CS) is the first determined for an endohedral compound to possess complete order of the cage as well as of the cluster inside, providing exquisite detail of the interplay between the geometry of the cage and that of the cluster inside, including the Sc-S-Sc angle. The Sc2S@C82 (C3V) crystal structure exhibited an ordered cage but some cluster disorder, and the Sc-S-Sc angle was observed to be very different from that of the CS isomer. Very recent X-Ray crystallographic results for another member of the scandium sulfide family, Sc2S@C72, indicates the presence of a never reported C72 cage with two IPR violations and, as usual, the two pentalene units are adjacent to the two Sc ions. The cage selected is isomer 10,528 out of 11,190 (C72 has only one IPR isomer). Very recently we found that Sc2S@C70 possesses a carbon cage that has never been reported before, cage #7,892, with two IPR violations. Within this family we have also identified two new isomers of Sc2S@C80, and from their UV-Vis spectra we know that these are cages that have never been reported before.


FK-2:L13  Clusterization of Shungite Nonplanar Graphenes in Water and its Hybrids
N.N. ROZHKOVA¹, S.S. ROZHKOV¹, A.A. MIKHAILINA¹, E.F. SHEKA², ¹Institute of Geology Karelian Research Centre RAS, Petrozavodsk, Russia; ²Peoples' Friendship University of Russia, Moscow, Russia

The recent burst of activity surrounding the solution-phase production of graphene is incomparable with a little progress that has been made toward the generation of graphene dispersions with tailored thickness, lateral area, and shape. Otherwise clusterization of graphene flakes in a stable aqueous dispersion of shungite carbon (ShC) nanoparticles, prepared by processing of natural carbonaceous raw material (shungite) in water, is a well reproducible process. The condensation of aqueous ShC dispersion was accompanied by the aggregation of nanoclusters followed by the formation of a 3-dimensional net with nodes in the form of distinct globules coinciding in size with the clusters in the dispersion detected by DLS. The globules are formed of nonplanar graphenes ~1 nm, kept together due to the confined water. Recreation of ShC origin at the quantum level was carried out based on the empirical and computat ional data obtained for graphenes.
The dispersion of ShC clusters was used in preparation of hybrid materials, namely protein-ShC, ShC-Pt and ZnS:Cu-ShC. Characteristic features of the new hybrids as well as a source of many-sided character of ShC are discussed.

 
Session FK-3 - Properties

FK-3:IL01  Structure, Properties, and Applications of Nanodiamonds
V.N. MOCHALIN, I. NEITZEL, A. PENTECOST, Y. GOGOTSI, Department of Materials Science & Engineering, Drexel University, Philadelphia, PA, USA

Nanodiamond is one of the most promising carbon nanomaterials for different applications varying from lubrication to biomedical and composite applications [1]. 5nm diamond particles with large accessible surface and tailorable surface chemistry have unique optical, mechanical and thermal properties, and are non-toxic. To fully exploit the potential of nanodiamond, attention must be paid to its purity, surface chemistry, and dispersion quality. Purification, characterization, and surface modification of nanodiamond for different applications will be discussed. Surface modification improves dispersion of nanodiamond in polymers. Reactions of nanodiamond functional groups with polymers bring the nanocomposite design to a conceptually new level, allowing for creation of covalent nanofiller-matrix interface with desired properties. The non-toxic fluorescent nanodiamond introduced into biodegradable polymers provides increased strength, visual monitoring, enhanced biomineralization, and release of growth factors and drugs attached to its surface. In drug delivery, rational surface modification allows for enhanced adsorption and chemical binding of the drugs to nanodiamond for sustained or triggered release.
1. Mochalin, V. N.; Shenderova, O.; Ho, D. Nature Nanotechnol. 2012, 7, 11-23


FK-3:IL07  Thermionic and Photon-enhanced Emission from CVD Diamond: Influence of Nanostructure, Doping, and Substrate
R.J. NEMANICH, M.D. BROWN, G. HEMBREE, F.A.M. KOECK, TIANYIN SUN, Department of Physics, Arizona State University, Tempe, AZ, USA

Thermionic electron emitters based on doped diamond films have shown significant emission at less than 500°C. Results have established that it is necessary to control the electron affinity, doping levels and concentration, and band bending, and these properties have been achieved with engineered multilayered structures with controlled morphology, doping and substrate. Recently, visible light photo-electron emission has been demonstrated using the same diamond film emitters. This report presents a spectroscopic and surface electron microscopy study of photo- and thermionic emission from nitrogen and phosphorus doped diamond films with controlled morphology on metal and silicon substrates. Electron emission spectra were recorded to 500°C, while illuminated with selected wavelength light. The emission spectra show a significant increase of the photo-emission intensity with elevated temperature, which is related to a decrease of the work function and/or increased carrier generation at the diamond-silicon interface. The photo enhanced emission is attributed to an increase of the electron quasi Fermi level due to the non-equilibrium excitation. The results suggest new configurations for efficient direct energy conversion.
Research supported by the US Office of Naval Research.


FK-3:IL08  Plasma Hydrogenation of Nanodiamonds: Fundamentals and Surface Properties
J.C. ARNAULT, T. PETIT, H.A. GIRARD, C. GESSET, A. TROUVÉ, P. BERGONZO, CEA, LIST, Diamond Sensors Laboratory, Gif sur Yvette, France

Properties of nanodiamonds (NDs) can be tuned playing with their surface chemistry. Atomic hydrogen produced under microwave field leads to the etching of non-diamond carbon, the reduction of oxygen species and the formation of C sp3-H bonds. Kinetics of this hydrogenation technique were studied by sequential surface analysis. Using a home-made MPCVD reactor, optimal conditions were applied to produce large amounts of H-NDs.
A high affinity of NDs-H toward water molecules was demonstrated by adsorption isotherms (BET) with more hydrophilic sites compared to NDs-COOH. As a consequence, stable NDs-H suspensions were obtained in water exhibiting a positive Zeta potential (ZP), + 45 mV at pH= 7.4. Its origin was related to a transfer doping occurring onto 5 nm diamond nanoparticles based on the diamond semi-conductive behavior.
The chemical reactivity of NDs-H was investigated via photochemical reaction with alkenes or diazonium chemistry. Their behaviour reveals similar to the one of hydrogenated diamond films. NDs-H in aqueous solution also revealed an unexpected behavior. After acid addition, a strong Coulomb coupling between NDs-H and adsorbed counterions induces their self-assembly into organized macro-structures reaching millimeter scale.


FK-3:IL09  Chemically Modified Graphene Heterostructures
M.C. HERSAM, Northwestern University, Evanston, IL, USA

The outstanding properties of graphene have been established on pristine samples in idealized conditions. However, for most applications, graphene needs to be chemically functionalized in a manner that either preserves its intrinsic properties or modifies its properties in a manner that enhances functionality. Towards these ends, several noncovalent chemistries have been demonstrated and characterized at the molecular scale with ultra-high vacuum scanning tunneling microscopy including 3,4,9,10-perylenetetracarboxylic dianhydride and 10,12 pentacosadiynoic acid. These self-assembled monolayers are shown to be effective atomic layer deposition seeding layers for high-k dielectrics (e.g., Al2O3 and HfO2). Beyond noncovalent self-assembled monolayers, this talk will also explore covalent modification schemes for graphene based on free radical chemistries. In particular, atomic oxygen has been established as an effective method for homogeneously and reversibly functionalizing graphene with epoxide groups. In addition to chemically doping graphene, epoxidation yields local modification of the graphene bandstructure and provides pathways for further chemical functionalization, thereby expanding the suite of chemically modified graphene heterostructures.


FK-3:IL10  Raman Fingerprint of Aligned h-BN/Graphene Superlattices
C. CASIRAGHI,  School of Chemistry, University of Manchester, Manchester, UK

Graphene placed on hexagonal-Boron Nitride (h-BN) experiences a superlattice (Moire') potential, which leads to a strong reconstruction of graphene's electronic spectrum with new Dirac points emerging at sub-eV energies [1-2]. In this talk I will show the effect of such superlattices on graphene's Raman spectrum [3]. In particular, the width of the 2D peak is found to be exquisitely sensitive to the misalignment between graphene and h-BN lattices. This allows high-throughput and non-destructive identification of aligned graphene/h-BN superlattices, making Raman spectroscopy a fundamental tool in the fabrication of graphene superlattices based-devices.
[1] J.R. Wallbankey al, Phys. Rev. B87, 245408 (2013)
[2] L. A. Ponomarenko et al, Nature 497, 594 (2013)
[3] A. Eckmann et al, submitted


FK-3:IL11  The Uniqueness of Physical and Chemical Natures of Graphene: their Coherence and Conflicts 
E.F. SHEKA, Peoples' Friendship University of Russia, Moscow, Russia

Molecular-crystalline duality of graphene ensures a tight alliance of its physical and chemical natures, each of which is unique in its own way. The paper examines the physical-chemical harmony and/or confrontation of graphene in terms of the molecular theory of graphene. Chemistry that is in harmony with graphene physics expectations involves: small mass of carbon atoms, which provides a lightweight material; sp2 configuration of the atoms valence electrons, ensuring a flat 2D structure of condensed benzenoid units; high strength of C=C valence bonds responsible for exclusive mechanical strength. Chemistry that is in conflict with graphene physics expectations covers: radical character of graphene material; collective character of electronic system of graphene, preventing from localization of its response on any external impact; a high propensity to sp2  sp3 transformation of atoms valence electrons, which violates flat 2D structure of graphene solid; molecular nature of graphene magnetism and mechanics, making them size and shape dependent; topochemical character of intermolecular interaction, which complicates graphene standing in media. Here’s why the graphene stability, required for physical applications, primarily necessitates the inhibition of its radicalization. Deposition of graphene monolayers on substrates is seen as a promising method.


FK-3:IL12  Ultrafast Dynamics in Graphene 
TING YU, Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore; Department of Physics, Faculty of Science, National University of Singapore, Singapore; Graphene Research Center, National University of Singapore, Singapore

In this report, ultrafast optical properties of graphene have been studied by use of steady-state and time-resolved spectroscopic techniques. Carrier dynamics of monolayer graphene, stacked and suspended few-layer graphene films were measured in the broad visible spectral range by femtosecond pump/probe spectroscopy. The time scales of carrier-carrier scattering, carrier-optical phonon scattering (c-op) and optical phonon-acoustic phonon (op-ap) scattering have been obtained and their roles in carrier relaxation process are distinguished. Meanwhile, there are several unusual quasiparticle interactions in graphene samples, including optical phonon emission and absorption, coherent phonon generation, etc. In general, carrier-carrier scattering (<60 fs) resulted into intraband carrier equilibration in graphene. The following carrier relaxation was regulated by c-op interaction. When the probe wavelength spreads to near infrared, we observe the transformation of carrier decay pathways from monoexponential c-op scattering to double exponential decay due to c-op and op-ap scattering.

 
Session FK-4 - Applications

FK-4:IL02  Boron Doped Diamond Biotechnology: From Sensors to Neurointerfaces
P. BERGONZO, C. HÉBERT, E. SCORSONE, H. GIRARD, CEA LIST, Diamond Sensors Laboratory, Gif-sur-Yvette, France; L. ROUSSEAU, M. COTTANCE, G. LISSORGUES, ESIEE-Paris, ESYCOM University Paris-EST, Cité Descartes, Noisy le Grand Cedex, France; A. BENDALI, M. DJILAS, E. DUBUS, J. DEGARDIN, S. PICAUD, INSERM,U968 Institut de la vision Paris, France; B.YVERT, CNRS, Institut des Maladies Neurodégénérative, UMR5293, Bordeaux,Talence, France

Boron doped nanocrystalline Diamond (B-NCD) is known as a remarkable material for the fabrication of sensors taking advantage of its biocompatibility, electrochemical properties, and stability. Sensors can be fabricated to directly probe physiological species from biofluids (e.g. blood or urine) as will be presented. In collaboration with electrophysiologists and biologists, the technology was adapted to enable structured diamond devices, such as MicroElectrode arrays (MEAs), i.e. common electrophysiology tools enabling to probe the neuronal activity distributed over large populations of neurons or of embryonic organs. Specific MEAs can be also used to build neural prostheses or implants to compensate function losses due to lesions or degeneration of part of the Central Nervous System (CNS) such as for Parkinson disease treatment, or for cochlear or retinal implants, those latter exhibiting real interests as biocompatible neuroprostheses for in-vivo neuronal stimulations.


FK-4:IL03  Nanocrystalline Diamond for Micro-Electro-Mechanical Systems
O.A. WILLIAMS, School of Physics and Astronomy, Cardiff University, Cardiff, UK

Nanocrystalline diamond (NCD) is a cheaper, more device ready form of thin film diamond which offers many of the extreme properties of bulk diamond at a substantially reduced cost. NCD can be grown as thin as 30nm on various substrates such as Si, SiO2, CMOS, Ge, refractory metals etc. NCD is by definition not self supported due to the thin nature of the material, but this offers many advantages when it comes to the fabrication of such devices as Micro-Electro-Mechanical Systems (MEMS), tribological coatings, transparent electrochemical electrodes etc.
In this talk the growth of NCD by MWPECVD will be discussed. The purification of diamond nanoparticles produced by detonation and their application to diamond nucleation will also be demonstrated. The plasma parameters and nucleation strategies required to produce thin films of NCD with bulk diamond properties will be defined. Young’s Modulus values up to 1100 GPa, control of conductivity via boron doping over 12 orders of magnitude as well as superconductivity at low temperatures will be demonstrated. MEMS devices fabricated from NCD and their characterisation will also be discussed.


FK-4:IL04  High Electric Field Diamond Power Devices
E. GHEERAERT, University of Grenoble-Alps, Grenoble, France

Diamond is a very attractive material for high power and high frequency electronic applications because of its exceptional physical properties. But diamond devices face one specific difficulty: at room temperature, because of the high ionisation energy of dopants, 0.38 eV for boron and 0.6 eV for phosphorus, free carrier density is very low at room temperature, and resistivity is consequently very high. Ionization energy can be reduced with an increase in the doping concentration, down to zero at the metal-insulator transition, but it also induces a detrimental decrease in the carrier mobility.
Different solutions have been studied and will be presented, such as the delta doping, that was supposed to increase the carrier concentration without reducing the mobility, the accumulation mode of the MOS transistor and finally the full boron ionization using a thermal avalanche process.
Results are very encouraging for the fabrication of high power devices.


FK-4:IL05  Compact High Voltage Power Switches Based on PIN Diamond Diode Emitters
D. TAKEUCHI, T. MAKINO, H. KATO, M. OGURA, H. OHASHI, H. OKUSHI, S. YAMASAKI, Energy Technology Research Institute, AIST, Japan; S. KOIZUMI, Wide Bandgap Materials Group, NIMS, Japan; all Advanced Low Carbon Society Technology Development Program (ALCA), JST c/o AIST, Japan, and Core Research for Evolutional Science and Technology (CREST), JST c/o AIST, Japan

Vacuum has been recognized a good insulator, and such a compact high voltage switch as that conventional semiconductor devices could not realize has been proposed with electron emitters. [1] However, one of the most critical requirements for the vacuum switch is high current density, scalability and uniformity in on-states.
This paper introduces our recent achievements on a 10kV vacuum power switch with a NEA of diamond PIN electron emitter. Experimental results indicate high uniformity and high emission efficiency without any current concentration owing to a stable negative electron affinity (NEA). This breakthrough with an efficiency of 73% at 9.8kV was attributed to a combination of (1) the NEA, (2) a high electron injection operation of PIN diamond diode at RT, and (3) the good insulation of vacuum. Taking into the account of the electron emission from diamond PN diode, whose amount was closed to 10 % of forward current, this result proves a principle of vacuum power switches over 100 kV with an efficiency beyond 99.9%.
This research was partially supported by Grants-in-Aid for Scientific Research 21360174 of JSPS, and a part of this work was conducted at the Nano-Processing Facility, supported by IBEC Innovation Platform, AIST.
[1] T. Ono et al., Proc. ISPSD'98, 151(1998)


FK-4:IL06  Squeezing Water between Graphene Sheets: Implications for Transport through Graphene Oxide Membranes
HWAY CHUAN KANG, Department of Chemistry and Yale-NUS College, National University of Singapore, Singapore

There has been significant effort in nanotechnology to develop highly efficient separation membranes for applications in industry and medicine [1].  In particular, nanomaterials represent a class of promising materials in this respect, leading to much interest in the selective transport of molecules through membranes of graphene and graphene-related membranes  [2].  This potential for the separation of molecules was recently illustrated by the discovery that water flows through graphene oxide membranes at many orders of magnitude faster than even a small molecule like helium [3].   In addition, this water transport rate is observed to decrease tremendously when the distance between the graphene layers are reduced from 10 Å to approximately 7 Å [3].  We explore this behaviour by examining the energetics of water molecules and clusters “squeezed” between graphene sheets using density functional theory calculations with van der Waals corrections.  We will present results for the energy of trapping water between graphene sheets, the intermolecular interactions between the trapped water molecules, and the potential energy corrugation due to the graphene.  We focus on how these interactions depend upon the distance between the graphene sheets in order to understand the dramatic decrease in the transport rate as this distance decreases to less than 7 Å. We also compare the energy for trapping water between graphene sheets to that for trapping Ar. Our results quantify these interactions and are consistent with experimental measurements thus providing insight on how the water transport rate depends upon distance between graphene sheets, and how the transport rate for water can be considerably larger than for other gases such as argon and helium.
References
[1] K. Scott, Handbook of Industrial Membranes, 245 (Elsevier, 1999)
[2] D.R. Paul, Creating New Types of Carbon-Based membranes, Science 335, 413 (2012) 413-414.
[3] R.R. Nir, et al, Umimpeded permeation of water through helium-leak-tight graphene-based membranes, Science, 335, (2012) 442-444.


FK-4:IL07  Graphene-based Nanosandwiches for Energy Storage and Conversion
XINLIANG FENG, Max Planck Institute for Polymer Research, Mainz, Germany

Recent progress of graphene research has triggered wide interest in 2D nanomaterials and related porous nanocomposites other than carbons. Here we present a bottom-up assembly approach to the fabrication of nanosandwiches based on chemically derived graphene. Different graphene-based porous nanosheets such as carbon, metal, metal oxide, and nanohybrides will be produced to possess the intriguing features such as thin thickness, large aspect ratio, high monodispersity and large surface area. Further, nanosandwiches based on graphene coupled with organic porous materials will be produced. The porous features of such graphene/organic porous materials can be tailored at the molecular level. Finally, 3D macroporous architectures will be built up based on the assembly of graphene sheets and nanosandwiches. These materials show hierarchical porous structures with high surface areas which can facilitate the diffusion of guest ions or molecules in many electrochemical systems. As the consequence, graphene-based nanosandwich materials may hold great potential in the areas of catalysis, sensors, supercapacitors and batteries.


FK-4:IL08  Graphene Applications in Sensors and Analog Devices
A.A. BALANDIN, Nano-Device Laboratory, Department of Electrical Engineering and Materials Science and Engineering Program, Bourns College of Engineering, University of California - Riverside, Riverside, CA, USA

The most promising practical applications of graphene are likely those that are not strongly hampered by the absence of the energy band gap but rather rely on graphene’s exceptionally high electron mobility, thermal conductivity, saturation velocity, and the possibility of tuning the carrier concentration with the gate over an exceptionally wide range. Apart from thermal management applications of graphene that are already entering the market [1-2], the electronic applications that fall into this category are those in chemical sensors, transparent electrodes, ultra-fast transistors for communications, interconnect wiring, and various electrodes. In this talk I will review our results on graphene applications in selective gas sensing [3-4] and discuss importance of low-frequency 1/f noise for creating an “ultimate” sensor (f is the frequency) [5]. Our results indicate that vapors of different chemicals produce distinguishably different effects on the low-frequency noise spectra of graphene. It was found that some gases change the electrical resistance of graphene devices without changing their low-frequency noise spectra while other gases modify the noise spectra by inducing Lorentzian components with distinctive features [3-4]. The characteristic frequency of the Lorentzian noise bulges in graphene devices is different for different chemicals and varies from 10 – 20 Hz to 1300 – 1600 Hz for tetrahydrofuran and chloroform vapors, respectively. The obtained results indicate that the low-frequency noise in combination with other sensing parameters can allow one to achieve the selective gas sensing with a single pristine graphene transistor. This method of gas sensing with graphene does not require graphene surface functionalization or fabrication of an array of the devices with each tuned to a certain chemical. From the other side, in analog electronics, the low-frequency 1/f noise hampers the operation of numerous devices and circuits, and can be a significant impediment to development of practical applications from new materials. Graphene offers unique opportunities for studying 1/f noise because of its two-dimensional structure and carrier concentration, which can be tuned over a wide range. The creation of practical graphene-based devices will also depend on our ability to understand and control the low-frequency noise in this material system. I will review the characteristic features of 1/f noise in graphene and few-layer graphene, and examine the implications of such noise for the development of graphene-based analog electronics and sensors.
This work was supported, in part, by the Semiconductor Research Corporation (SRC) and Defense Advanced Research Project Agency (DARPA) through STARnet Center for Function Accelerated nanoMaterial Engineering (FAME) and by the National Science Foundation (NSF) projects US EECS-1128304, EECS-1124733 and EECS-1102074.


FK-4:IL09  Technology of Field Emitters Based on Carbon Nanotubes 
M.L. TERRANOVA, Dip. di Scienze e Tecnologie Chimiche, MINIMAlab, University of Roma Tor Vergata, Roma, Italy; and NANOSHARE Srl

Electron sources based on field emission (FE) of carbon nanotubes (CNT) are presently considered the best choice for generation of free electrons in vacuum, and CNT-based FE vacuum devices are proposed for integration in high-frequency/power and size-reduced electronics. To utilize the advantages offered by CNT, an essential task is the engineering of emitting sources with the characteristics required for each application. This can be pursued by tailoring the CNT deposits and shaping the emitters.  
Cathodes may be fabricated exploiting the emission features from  isolated CNT bundles or from larger aggregates, from continuous deposits or from patterned sites, from macroscopic fibers, from laser-shortened nanotubes, from nanodiamond-coated CNT mats. Key points common to all the systems are good emission behaviour, short time response, mechanical resistance and chemical properties.
This presentation will illustrate some examples of CNT-based cold cathode designed for specific technologies, along with the  methodologies settled up for their manufacturing:
- X-ray portable tubes with low power consumption and reduced focal spot (FP7-SME : NANORAY)
- Optically modulated miniaturized THz amplifiers (FP7 : OPTHER)
- Electron gun  for injection in plasma reactors and ECR ion sources (INFN : CANTES)


FK-4:IL10  Electrochemical Behavior of Carbon Nanofibers and Related Materials
V. PRESSER, D. WEINGARTH, J.S. ATCHISON, M. ASLAN, INM - Leibniz Institute for New Materials & Saarland University, Saarbrücken, Germany

Porous carbons dominate applications such as gas and energy storage and catalysis. As energy storage devices move away from conventional powder films towards 3D architectures, the ability to control and modify the shape of carbon films has become a key aspect. Starting with a polymer, complex shapes like fibers, foams, or films can be achieved. After pyrolysis, complex-shaped carbides are obtained, which in turn can be transformed into extremely high surface area carbons. In particular, fibrous materials such as electrospun nanofelts have demonstrated excellent power handling ability leading to energy storage devices showing fast charge and discharge rates. At the same time, such fiber electrodes eliminate the need for conductive additives or organic binders used in conventional devices while remaining flexible and opening up novel applications, such as wearable electronics. The use of polymer-derived ceramics makes it possible to synthesize hierarchical porous carbons with a large pore volume either with ordered or randomly arranged mesopores. Such hierarchic porous carbon materials can decrease transport limitations commonly encountered in microporous systems. However, a large pore volume associated with micropores is still required to obtain a high energy density.


FK-4:IL12  Catalytic Application of Nanoporous Carbon Materials
B. HASSE, J. GLÄSEL, F. REIßNER, P. HAUSMANN, C. DICENTA, B.J.M. ETZOLD, Lehrstuhl für Chemische Reaktionstechnik, Friedrich-Alexander Universität Erlangen-Nürnberg, Erlangen, Germany

In heterogeneous catalysis the choice of catalyst may have drastic influence on product selectivity and the amount of required process energy. As a consequence a continuous improvement of catalytic materials is aimed for. Carbon is chosen as catalyst support especially at harsh reaction conditions, like hydrothermal ones or alkaline/acidic environment. Despite the good availability of common carbon materials like activated carbon or carbon black, these materials lack of tuneability, purity and reproducible material properties. As a consequence, there is a lack of structure-activity relationships for carbonaceous catalysts.
Novel carbon nanomaterials, which allow to tune material properties can be used to close the gap of understanding for carbonaceous catalysts. It will be shown that for successfully employing these materials it is crucial to preserve the defined properties during catalyst preparation and catalytic application. If so a catalyst optimization driven by fundamental understanding despite empiric testing is possible.
The authors gratefully acknowledge the funding of the European Union Seventh Framework Programme (FP7/2007-2013) within the project SusFuelCat under grant agreement No. 310490 (www.susfuelcat.eu) and funding by the German Research Council (DFG).


FK-4:L13  Carbon Nanomaterials for Capacitive Energy Storage
Y. GOGOTSI, Department of Materials Science and Engineering and A.J. Drexel Nanotechnology Institute Drexel University, Philadelphia, PA, USA

This lecture will provide a brief overview of research in the area of nanostructured carbon materials used for capacitive storage of electrical energy. Electrochemical capacitors or “supercapacitors” are devices that store electrical energy electrostatically and are used in applications where batteries cannot provide sufficient power or charge/discharge rates, or when a long service life (up to 1 million of cycles) is needed. Until now, their higher cost, compared to batteries, has been limiting the use of supercapacitors in household, automotive and other cost-sensitive applications. We describe the material aspects of supercapacitor development, address unresolved issues and outline future research directions.
High surface area carbon materials are widely used as supercapacitor electrodes. Graphene, nanotubes, activated carbons, template carbons, carbon onions and carbon black are among many materials being used in supercapacitors. Extraction of metals from carbides can generate a broad range of potentially important carbon nanostructures, which range from porous carbon networks to onions and nanotubes. They are known as Carbide-Derived Carbons (CDC). The CDC structure depends on the crystal structure of the carbide precursor as well as process parameters including temperature, time and environment. Extraction of silicon, boron, aluminum, zirconium or titanium from their respective carbides by chlorine at 200-1200°C results in the formation of micro- and mesoporous carbons with the specific surface area up to 3000 m²/g.  CDC technology allows the control of carbon growth on the atomic level, monolayer by monolayer, with a high accuracy. It will be shown that the pore size to ion size ratio determines the efficiency of electrochemical energy storage systems. Design of supercapacitor electrodes using nanoporous carbons (3-D), graphene (2-D), carbon nanotubes (1-D) and carbon onions (0-D) for will be addressed.
 

FK-4:L14  Design and Fabrication of Printed, Carbon Nanotube Transistors Operating in the GHz Range for Electronic Systems
J. VAILLANCOURT, A. AKYURTLU, C. ARMIENTO, University of Massachusetts, Lowell, MA, USA

The ability to print electronics on flexible materials is expected to be an enabling technology in future electronic systems. The advantages of lower cost, flexibility, and large area functionality are expected to benefit applications as diverse as biomedical monitoring, RFID tags, and radar systems. Many of these applications require high frequency transistors capable of operating in the GHz range. CNTs are attractive as the active material for printed transistors based on their higher mobility compared with alternatives such as organic semiconductors. High-frequency printed transistors can be used in subsystems that also incorporate metamaterials and electromagnetic devices such as antennas. This talk will describe research on printed CNT-based transistors fabricated using aerosol jet and capillary printing techniques. The design and fabrication tradeoffs of these transistors will be described with respect to the size, formulation, and alignment of the CNTs. RF characterization of these transistors will be analyzed to optimize their design for high frequency applications.


FK-4:L15  Application of Carbon-based Gradient Materials for the Design of Rail Bumpers
P. ZAKIEWICZ, P. PACKO, K. KOZLOWSKA, T. UHL, Department of Robotics and Mechatronics, AGH-University of Science and Technology, Krakow, Poland; K. KYZIOL, Department of Material Engineering and Ceramics, AGH-University of Science and Technology, Krakow, Poland; J. MIZERA, Materials Design Division, Warsaw University of Technology, Poland

The paper focuses on experimental study of polymer cover dedicated to rail buffer which is additionally covered by thin layers (deposited by CVD methods) and without these layers - in order to compare the key properties. Diamond like carbon (DLC) layers and DLC with gradient CNH and CNH-SiCNH layer were deposited. Performed experiments show the influence of chemical composition of gas environment, process parameters and the surface preparation on mechanical and tribological properties such as friction coefficient, roughness, hardness, elastic modulus and a level of adhesion of thin layers to polymer substrate. The results allow to evaluate the influence of thin coatings on tribological properties of a rail bumper surface and shows possible optimization possibilities.


FK-4:L16  Graphene Oxides and their Hybrids for Solar to Hydrogen and CO2 Photofixation Applications
LI-CHYONG CHEN¹, YAN-GU LIN^{1, 2}, HSIN-CHENG HSU³, YU-CHUNG CHANG³, INDRAJIT SHOWN², CHEN-HAO WANG³, KUEI-HSIEN CHEN^{1, 2}, ¹Center for Condensed Matter Sciences, National Taiwan University, Taipei, Taiwan; ²Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, Taiwan; ³Department of Materials Science and Engineering, National Taiwan University of Science and Technology, Taipei, Taiwan

Photocatalytic conversion of carbon dioxide (CO₂) to hydrocarbons such as methanol makes possible simultaneous solar energy harvesting and CO₂ reduction, two birds with one stone for the energy and environmental issues. This work describes a high photocatalytic conversion of CO₂ to methanol using graphene oxides (GOs) as a promising photocatalyst. The modified Hummer's method has been applied to synthesize the GO based photocatalyst for the enhanced catalytic activity. The photocatalytic CO₂ to methanol conversion rate on modified graphene oxide is 0.172 μmol g-cat⁻¹ h⁻¹ under visible light, which is six-fold higher than the pure TiO₂. Meanwhile, we have developed a novel one-step and effective electrochemical (EC) method to directly exfoliate graphite into thin reduced graphene oxide (RGO) nanosheets at room temperature. The oxidation degree of the RGOs depends on the switching potentials of the EC synthesis. The high switching potential can significantly increase the C/O ratio of the RGOs. The ability to control the light-absorption of the RGOs by simply adjusting the switching potentials can be further achieved. Moreover, we also construct an RGO–ZnO heterojunction and investigate its photoelectrochemical (PEC) properties. The results show that highly photoactive RGO as a photosensitizer can make H₂ evolution easier and improve the photoconversion ability of ZnO under visible-light irradiation. This approach presents us with a possibility for the environmentally friendly, ultrafast, low-cost, and large-scale production of RGOs and great potential in solar-energy conversion applications of graphene-based materials. Further, Cu and MoS₂ nanoparticles were deposited on GO as co-catalysts to enhanced the photocatalysis reaction. Not only methanol, but also acetaldehyde was detected. Total solar to fuel yield of 6.8 μmole g-cat^-1 h^-1 has been achieved, which is 170 times enhancement relative to the commercial P-25 photocatalyst. In all the above-mentioned hybrids, the photo- catalytic performance is always much better than that of constituent component when used alone. Detailed preparation and characterization of the catalysts will be presented. The role and interplay of the constituent components will also be discussed in this paper.


FK-4:L18  Electrochemical Measurements and Metal Deposition on Graphene Layers at Liquid/Liquid Interface
P.S. TOTH, R.A.W. DRYFE, School of Chemistry, University of Manchester, Manchester, UK

Polarisable liquid/liquid interfaces (ITIES) have been investigated for over 30 years, mainly in the context of ion and electron transfer reactions. The potential drop across the ITIES is developed over a region of 1 to 10 nm. The nucleation of metallic structures, catalytic activity e.g. hydrogen and oxygen evolution, the assembly of nanoparticles or catalytic nanoparticles have received a great interest in the last years.
Graphene nanomaterials were prepared in two ways: exfoliation from natural graphite in 1,2-dichloroethane dispersion and chemical vapor deposition (CVD) on copper foil. Both types of material were assembled at the ITIES. The graphene materials before and after assembly were characterized by Atomic Force Microscopy and Raman spectroscopy.
The electrochemical reactivity of nanostructures was probed by model redox species at the ITIES. In situ electrochemical and spontaneous metal deposition at the interface assembled carbon nanomaterials were studied, and the morphology of the deposited metal was determined using electron microscopy.
Deeper understanding of the behavior of model redox couples on graphene is of primary importance in the exploitation of this material in catalytic processes, such as of the oxidation of low molecular weight alkanes to liquid fuels.


FK-4:L21  Photo-thermal Desorption of Toluene from Single Walled Carbon Nanotube Adsorbent Pads in Air Samplers
C.T. LUNGU, J. OH, University of Alabama at Birmingham, Birmingham, AL, USA; E. FLOYD, University of Oklahoma, Oklahoma City, OK, USA

Activated Carbon (AC) is widely used to collect volatile organic compounds (VOCs) in air samplers. Laboratory analysis is performed by chemical or thermal desorption. Both these methods present limitations with respect to either sensitivity (chemical) or cost (thermal) and are time consuming. A technique that achieves partial desorption and improves sensitivity over chemical desorption would be desirable. Single Walled Carbon Nanotubes (SWNT) have similar VOC adsorption properties as AC. Camera flash has been used to ignite SWNT; therefore, light flash could be used for desorption. We prepared SWNT adsorbent pads, loaded them with toluene vapors and used light flash to achieve partial desorption.
Methods: Light flash of different energies is applied to AC and SWNT samples. Samples were loaded with toluene and flashed once per minute. Light is absorbed and converted into heat causing desorption. A photo ionization detector was used to quantify desorbed toluene mass.
Results: SWNT-felt desorption was nearly constant across successive flashes whereas SWNT-powder and AC-powder exhibit exponential decrease after first flash. At 435µg toluene and 4.7J flash, first flash and 10-flash desorption was: SWNT-felt 0.86%, 7.71%, SWNT-powder 0.57% and 2.92%, AC-powder 0.34% and 1.37% respectively.
Conclusions: Single flash desorption can deliver more sample to an analytical instrument than chemical extraction. SWTN-felt desorption is additive whereas SWNT-powder and AC are exponentially decreasing.


FK-4:L22  Understanding the Performance of Bucky Gel Actuators by Means of their Electrical Model
G. BUBAK, A. ANSALDO, D. RICCI, Istituto Italiano di Tecnologia, Robotics, Brain and Cognitive Sciences Department, Genova, Italy

The bucky gel actuator is a bimorph dry electrochemical device prepared by lamination of three layers. External layers are composite electrodes made from carbon nanotubes ground with imidazolium ionic liquid and polymer. The internal layer is the solid electrolyte consisting of ionic liquid incorporated into a polymeric matrix. Those actuators are lightweight, can operate at low voltage (2-5V) and generate higher force-for-unit-volume than natural muscles (~60 N.dm^-3). Although this material is an outstanding component to build actuators, we observed that one of the main issues that limits the performance of these actuators is charging speed along the actuator length. The resistance of the electrodes surface was measured using four-probe setup. Ionic conductivity of the electrolyte was investigated based on impedance spectroscopy. We present results demonstratin the influence of the utilizing of different types of carbon nanotubes and the explanation of phenomena employing RC transmission line models. In addition, strain-displacement and force-displacement characterizations were made and analysed together with the results of modelling.


FK-4:L23  Surface-modified Carbon Nanotubes Multifunctional Sensor
P. ZBYRAD^{1, 2}, K. GRABOWSKI¹, T. UHL¹, ¹AGH University of Science and Technology, Faculty of Mechanical Engineering and Robotics, ²AGH University of Science and Technology, Faculty of Materials Science and Ceramics, Krakow, Poland

Nowadays multipurpose, multifunctional sensors received a lot of attention in technological application areas. Sensors used today allow for measurement of various properties and are based on different operation principles. CNT-nanocomposite are the most promising material for multifunctional sensors. Carbon Nanotubes are one of the commonly used carbon allotropes. CNTs present excellent electrical and mechanical properties that might be used in various purpose. Modifications on Carbon Nanotube surface give opportunities to develop sensors which can work in few mode, i.e. we can measure strain and we can detect gas during sensor is working. Oxidation on CNT's surface is the first step to obtain reactive material suitable for specific application.
 
 
Poster Presentations

FK:P01  Reasearch of Diamond-like Carbon Film Deposited by Double Pulsed Laser
YONG CHENG, SHUYUN WANG, YIMIN LU, GUOJUN HUANG, YANLONG GUO,  XU LIU, BIN SUN, Opto-Electronics Facility of Wuhan Mechanical College, Wuhan, China

DLC Film was deposited by double beam pulsed lasers. KrF(248nm, 20ns) laser and Ti:Sapphire(800nm, 120fs) laser are used alternately to ablate graphite target. Through controlling parameters of two laser beams, double-layer DLC film is deposited on Si substrate. The hardness and inner stress of the multilayer DLC film changed gradually from substrate to atmosphere-interface. Nano-indenter, FT-IR spectroscopy and interferometer were used to test performance of the film. Results showed that DLC film deposited by double beam pulsed laser not only has high transmittance and hardness, but also the whole stress is effectively controlled. The film keeps well and has no nick after stuck by adhesive tape, rubbed by 9.8N rubber and dipped in salt liquor and boiling water. The fastness and anti-scratching performance of DLC film deposited by double pulsed lasers is much better than those by single beam pulsed laser.


FK:P02  Effect of Surface Morphology and Crystalline Orientation of Copper Substrate on the Quality and Structure of Graphene Synthesized by Chemical Vapor Deposition
A. IBRAHIM¹, A. OWAIS², M. ATIEH², R. KARNIK³, T. LAOUI¹, ¹Department of Mechanical Engineering, King Fahd University of Petroleum and Minerals, Dhahran, Saudi Arabia; ²Department Chemical Engineering, King Fahd University of Petroleum and Minerals, Dhahran, Saudi Arabia; ³Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA

Graphene has attracted attention in recent years because of its unique structure and properties, making it attractive for electronics, optoelectronics, nano-electromechanical systems, chemical and bio-sensing applications. Chemical Vapor Deposition (CVD) is extensively utilized for producing large area, high quality graphene films on suitable substrates. Copper (Cu) substrate is used mainly as a substrate and catalyst during graphene synthesis process by CVD method. Generally, Cu foils are polycrystalline and exhibit complex surface morphology. Before graphene growth Cu substrates undergo annealing process, in which, surface morphology, microstructure and crystallographic orientation of Cu are changed considerably. The purpose of the present work is to investigate deeply the effect of annealing process on the evolution of both surface morphology and crystalline orientation of two different commercial Cu substrates, and also to study their impact on the quality and structure of deposited graphene layers. In this study, graphene was grown on two different polycrystalline Cu foils using methane as the carbon source, the growth temperature was fixed at 1040oC. AFM,XRD, SEM and Raman spectroscopy will be utilized in characterization of both Cu substrates and graphene/Cu samples.


FK:P03  Large-scale Synthesis of Nanoporous Carbide-derived Carbons
A. GOGOTSI¹, Y. GOGOTSI², ¹Materials Research Centre, Kiev, Ukraine; ²A.J. Drexel Nanotechnology Institute, Department of Material Science and Engineering, Drexel University, Philadelphia, PA, USA

This presentation describes the formation of carbon from carbides and explains how to generate a variety of pore structures by controlling synthesis conditions.  Extraction of metals from carbides can produce a broad range of potentially important porous carbon materials. Extraction of silicon, boron, zirconium or titanium from their carbides results in the formation of amorphous or disordered graphitic nanoporous carbon (specific surface area up to 3000 m²/g), depending on the carbide structure, temperature and gas composition. This technology allows the control of carbon growth on the atomic level, monolayer by monolayer, with very high accuracy. These carbons, which we call Carbide Derived Carbons (CDC) have a tunable pore structure and can be used for selective adsorption, CO₂ capture, hydrogen and methane storage, as electrode materials in batteries and supercapacitors, gas separation membranes and other applications. The structure of the carbon is controlled by the structure of the carbide precursor as well as processing parameters including temperature, time and environment. The carbide-derived carbon (CDC) coatings on dynamic seals or SiC fibers provide excellent adhesion and a low friction coefficient in various environments. Scalable synthesis process with utilization of reaction products will be described.


FK:P06  A Facile Route for the Synthesis of Graphitic Carbon-Fe-based Nanocomposites from K2CO3-activated Sugarcane Bagasse
V. LORYUENYONG^{1, 2}, J. PHONGTHONGCHAROEN¹, K. KLOMCHIT¹, R. CHAIKLANG¹, A. BUASRI^{1, 2}, ¹Department of Materials Science and Engineering, Faculty of Engineering and Industrial Technology, Silpakorn University, Nakhon Pathom, Thailand; ²National Center of Excellence for Petroleum, and Advanced Materials, Chulalongkorn University, Bangkok, Thailand

In this study, we present the synthesis of Fe-graphitic carbon and magnetite Fe3O4-amorphous carbon nanocomposites from catalytic pyrolysis and carbonization of chemically-activated sugarcane bagasse under nitrogen atmosphere. Fe(NO3)3.9H2O was used as an iron precursor for preparing metallic catalyst and K2CO3 as an activating agent. The process was performed using a simple and low-cost chemical vapor deposition method. The obtained products were characterized by TGA, TEM, SEM, XRD, and BET specific surface area. It was observed that, at 800C, Fe(NO3)3.9H2O was decomposed and reduced to Fe3O4, forming magnetite Fe3O4-amorphous carbon nanocomposites. Graphitic carbon was, however, produced at temperatures between 900 and 1000C, at which the iron precursor was reduced into metallic Fe nanoparticles. BET specific surface area as high as 1159 m2/g could be attained from the Fe/graphitic carbon nanocomposite when carbonized at 1000C.


FK:P07  Modelling of the Low Molecular Fluoropolymer Forms. Characterization of the IR- and NMR Spectra
L. IGNATIEVA, Institute of Chemistry, FEB RAS, Vladivostok, Russia; V. BOUZNIK, A.A. Baykov Institute of Metallurgy and Material Science RAS, Moscow, Russia

Although fluoropolymers find an extensive application in many fields of industry, understanding of their structural features and interpretation of experimental data are not always unambiguous, in spite of active experimental studies. A detailed theoretical discussion is crucial in such cases. The IR and NMR spectroscopy methods are the informative experimental methods, but interpretation of the obtained data may be difficult. The problem of unambiguous and reliable interpretation of empirical data can be solved by performing quantum chemistry calculations of the molecular polymer units modulating polymer fragments or molecules of low molecular polymer forms. Last time the low molecular polymers are becoming increasingly important in the application. HF and DFT methods were used to calculate energy and topological parameters, IR- and NMR-spectra of the CnF2n-2 model molecules. The formation of radicals and branches in fluorocarbon polymers, geometric parameters, preferred conformations, identification polymer groups are discussed based on obtained results. The results of experimental investigations of fluoropolymers were explained on the basis of calculation results.


FK:P08  Effect of Explosive Processing on the Structure and Properties of Ultrafine Polytetrafluoroethylene
G.A. ZVEREV, L.N. IGNATIEVA, V.G. KURYAVYI, E.B. MERKULOV, A.B. SLOBODYUK, Institute of Chemistry FEB RAS, Vladivostok, Russia; N.A. ADAMENKO, A.V. KAZUROV, Volgograd State Technical University, Volgograd, Russia; V.M. BUZNIK, Institute of Metallurgy and Material Science, Moscow, Russia

The processing of UPTFE by explosive pressing leads to a number of changes in the original material. The most important result is the formation of a crust on the surface of the sample; the crust has a completely different morphology and phase composition. The regions of flattened particles linked by fibers are detected in the dark film; they resemble craze structures. Typically, crazes are formed during the thermomechanical stretching of PTFE films; in this case, they appear during explosive compression. In addition to PTFE, iron compounds are contained in these structures. On one hand, this result indicates a partial removal of the iron atoms from the steel tube during pressing; on the other hand, it opens a way for preparing a new composite material. At the molecular level, no radical changes occur in the material during processing. UPTFE preserves its features; that is, it is a low-molecular-weight fraction of PTFE, which in turn is composed of fractions having different molecular weight. However, the data of IR spectroscopy, NMR, and calorimetric analysis suggest that, under pressure, the amount of middle-molecular-weight fractions increases owing to a decrease in the content of low- and high-molecular-weight fractions.


FK:P12  Liquid Crystal Assisted Selective Separation of Large Graphene Oxide and its Size Dependent Oxygen Reduction Catalytic Effect
KYUNGEUN LEE, JIEUN KIM, JOON WOON LIM, SANG OUK KIM, IBS, KAIST, Daejeon, South Korea

We introduce a new self-separation of Large Graphene Oxide (LGO) flakes exploiting liquid crystalline phase formation. Moderately concentrated discotic GO aqueous solution spontaneously phase separates into isotropic phase and nematic phase. According to Onsager theory, larger flakes with higher aspect ratio tends to form nematic phase, while smaller flakes remain in isotropic phase. Simple isolation of bottom nematic phase (sLGO) resulted in the LGO dominant dispersion preparation. We employed this size selection principle to investigate the influence of GO flake size upon the material properties of reduced graphene oxide. The electrical properties of spin cast rGO films are thoroughly investigated in terms of the GO flake sizes in the precursor aqueous dispersions. Interestingly, nitrogen doping in order to inject more electron charge carrier exhibit different behavior following flake size. Therefore, it was experimentally confirmed that quaternary nitrogen doping site acts as the dominant catalytic site in oxygen reduction reaction.


FK:P14  The Possibilities of Graphenes Application in Textronic Devices
I. KRUCINSKA, M. PUCHALSKI, E. SKRZETUSKA, Lodz University of Technology, Department of Material and Commodity Sciences and Textile Metrology, Lodz, Poland

Graphene, because of its exceptional properties such as very good electrical conductance, flexibility and high optical transparency in visible light spectrum, has proved to be an excellent nanomaterial for modern electronic applications. The natural point of view is to use this new nanomaterial for the development of unique textronic devices such as sensory systems for monitoring human body's vital functions, and atmospheric composition. The present review shows the state of art of materials science and possibilities of the smart textiles design with graphene. The most promising applications of graphene for the design of textronic devises are the development of conductive polymer composites (CPC) and the development of inks and pastes for printing conductive tracks on textile materials. The paramilitary results of implementation of 2D carbon structure into clothes by using of Ink-Jet and screen printing methods will be presented.


FK:P15  Improvement of Performance of Paper Transistor Using Carbon-nanotube-composite Paper and Its Application to Logic Circuit
Y. HAMANA, Y. KAWAMURA, T. OYA, Yokohama National University, Yokohama, Japan

We propose development of an advanced type of a "paper transistor" using carbon-nanotubes(CNT)-composite papers(CNTCPs) and aim to apply our paper transistors to construction of logic circuits. It is known that the CNTs have many functions such as high electrical and thermal conductivities, and metallic and semiconducting properties. Our CNTCP that has various functions caused by the CNTs despite of the paper can be fabricated easily by scooping up and dried materials from a mixture of the CNT and pulp (paper materials) dispersions. Because the CNTs have the metallic or semiconducting properties, metallic- and semiconducting-CNTCPs can be fabricated. By preparing such CNTCPs and a normal paper as an insulator, we can produce the paper transistor as we have already proposed in CIMTEC 2012. In previous work, we confirmed our transistor as a prototype could operate as a p-type transistor. However, the sample had some problems, e.g., an internal resistance was rather high. In this study, we aim to overcome the problems by developing new making method for the CNTCP. As a result of experiments, we succeeded to obtain new paper transistors with good performance comparing with the previous one. Moreover, we try to construct a "paper logic circuit" by using our paper transistors.


FK:P16  Development of Carbon-nanotube-composite-thread and it's Application to "Thread Transistor"
M. YOSHIDA, T. OYA, Yokohama National University, Yokohama, Japan

We propose a development of a new functional thread that contains carbon-nanotubes (CNTs), i.e., a CNT-composite thread (CNTCT), and of a "thread transistor." The CNT is expected to be a next-generation material because it has a lot of useful characters, e.g., it can have both metallic- and semiconducting- characters. In contrast, the thread is flexible and often used in our life. In our study, we could develop the CNTCT easily by dipping thread in CNTs dispersion like dyeing. Here, we also develop and demonstrate a new type of a Field-Effect-Transistor (FET), i.e., the "thread transistor." To do this, we prepared a metallic (M)- and a semiconducting(S)-CNTCT. The S-CNTCT was coated by a non-conductive paint for simplicity. To construct the thread transistor, we tensed the S-CNTCT that played a role of channel for the FET and tied the M-CNTCT round the S-CNTCT as a gate electrode. The source and drain electrodes can also be materialized by tying the M-CNTCTs. As a result of measurement, a drain-to-source current could be measured in micro-amperes order. Moreover, the current could be controlled by the gate voltage.In this study, we succeeded to develop a "p-type thread transistor". We are going to develop a "n-type thread transistor" and a "thread logic device" near future.


FK:P17  Energy Gap Associated to Photocatalytic Activity of MWCNT/TiO2 Nanocomposites
S. DA DALT^{1, 2}, A.K. ALVES¹, J.S. PINTO¹, C.P. BERGMANN¹, ¹Department of Materials, Federal University of Rio Grande do Sul, RS, Brazil; ²Engineering Center, Federal University of Pelotas, RS, Brazil

Carbon nanotubes (CNTs) have been investigated for a wide range of applications. The combination of the CNT structure with TiO2 opens up various application possibilities: water separation for hydrogen generation, degradation of pollutants in aqueous contamination and sewage treatment, photoreduction of CO2 activity in self-cleaning air purification and dyes for solar cells. The CNT-TiO2 combination, when used as support, can facilitate a change in electron transfer, increasing the photocatalytic activity. Multi-walled carbon nanotubes/TiO2 (MWCNTs/TiO2) nanocomposites were prepared by the modified sol-gel method using MWCNTs, titanium (IV) propoxide and commercial TiO2 (P25) as titanium sources. The composites obtained from the titanium (IV) propoxide were prepared by solution processing followed by thermal treatment at 500° C. The results were associated with the characteristics of the nanocomposites structure using Raman spectroscopy. The photocatalytic activity on organic dye was associated to energy gap evaluated by diffuse reflectance spectroscopy.