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  • 1.
    Anoshkin, Ilya
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Nefedova, Irina
    Dmitri, Lioubtchenko
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Nefedov, Igor
    Räisänen, Antti
    Single walled carbon nanotube quantification method employing the Raman signal intensity2017Inngår i: Carbon, ISSN 0008-6223, E-ISSN 1873-3891, Vol. 116, s. 547-552Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A new technique for measuring the number of single walled carbon nanotubes (SWCNTs) and their concentration in a carbon nanotube layer is developed in this work. It is based on the G peak intensity of the Raman spectrum, together with precise mass and optical absorbance measurements. The dependence of the number of the carbon nanotubes on the phonon scattering intensity is observed. This method opens an opportunity for the quantitative mapping of sp2 carbon atom distribution in the SWCNT layers with a resolution limited by the focused laser spot size.

  • 2. Bhattacharya, K.
    et al.
    El-Sayed, R.
    Andón, F. T.
    Mukherjee, S. P.
    Gregory, J.
    Li, H.
    Zhao, Yinchen
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Funktionella material, FNM.
    Seo, W.
    Fornara, A.
    Brandner, B.
    Toprak, Muhammet Sadaka
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Funktionella material, FNM.
    Leifer, K.
    Star, A.
    Fadeel, B.
    Lactoperoxidase-mediated degradation of single-walled carbon nanotubes in the presence of pulmonary surfactant2015Inngår i: Carbon, ISSN 0008-6223, E-ISSN 1873-3891, Vol. 91, s. 506-517Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Carbon nanotubes (CNTs) may elicit inflammatory responses following pulmonary exposure. Conversely, enzymatic biodegradation of CNTs by inflammatory cells has also been reported. The aim of this study was to study the degradation of oxidized single-walled CNTs (ox-SWCNTs) by lactoperoxidase (LPO), a secreted peroxidase present in the airways, and whether pulmonary surfactant affects this biodegradation. To this end, ox-SWCNTs were incubated in vitro with recombinant bovine LPO + H<inf>2</inf>O<inf>2</inf> + NaSCN in the presence and absence of porcine lung surfactant (Curosurf®) and biodegradation was monitored using UV-Vis-NIR spectroscopy, Raman spectroscopy, and scanning electron microscopy. The interaction of recombinant LPO with bundles of ox-SWCNTs was confirmed by atomic force microscopy. Cell-free biodegradation of ox-SWCNTs was also observed ex vivo in murine bronchoalveolar lavage fluid in the presence of H<inf>2</inf>O<inf>2</inf> + NaSCN. Our study provides evidence for biodegradation of ox-SWCNTs with a lung surfactant 'bio-corona' and expands the repertoire of mammalian peroxidases capable of biodegradation of ox-SWCNTs. These findings are relevant to inhalation exposure to these materials, as LPO serves as an important component of the airway defense system.

  • 3. Bhattacharya, Kunal
    et al.
    El-Sayed, Ramy
    Andon, Fernando T.
    Mukherjee, Sourav P.
    Gregory, Joshua
    Li, Hu
    Zhao, Yichen
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Funktionella material, FNM.
    Seo, Wanji
    Fornara, Andrea
    Brandner, Birgit
    Toprak, Muhammet S.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Funktionella material, FNM.
    Leifer, Klaus
    Star, Alexander
    Fadeel, Bengt
    Lactoperoxidase-mediated degradation of single-walled carbon nanotubes in the presence of pulmonary surfactant (vol 91, pg 506, 2015)2015Inngår i: Carbon, ISSN 0008-6223, E-ISSN 1873-3891, Vol. 95, s. 766-766Artikkel i tidsskrift (Fagfellevurdert)
  • 4.
    Fan, Xuge
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Elgammal, Karim
    KTH, Centra, SeRC - Swedish e-Science Research Centre. KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik.
    Smith, Anderson D.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektronik, Integrerade komponenter och kretsar.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektronik, Integrerade komponenter och kretsar.
    Delin, Anna
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap. KTH, Centra, SeRC - Swedish e-Science Research Centre. Department of Physics and Astronomy, Materials Theory Division, Uppsala University, Box 516, SE-75120 Uppsala, Sweden.
    Lemme, Max C.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektronik, Integrerade komponenter och kretsar. Department of Electronic Devices, RWTH Aachen University, 52074 Aachen, Germany.
    Niklaus, Frank
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Humidity and CO2 gas sensing properties of double-layer graphene2018Inngår i: Carbon, ISSN 0008-6223, E-ISSN 1873-3891, Vol. 127, s. 576-587Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Graphene has interesting gas sensing properties with strong responses of the graphene resistance when exposed to gases. However, the resistance response of double-layer graphene when exposed to humidity and gasses has not yet been characterized and understood. In this paper we study the resistance response of double-layer graphene when exposed to humidity and CO2, respectively. The measured response and recovery times of the graphene resistance to humidity are on the order of several hundred milliseconds. For relative humidity levels of less than ~ 3% RH, the resistance of double-layer graphene is not significantly influenced by the humidity variation. We use such a low humidity atmosphere to investigate the resistance response of double-layer graphene that is exposed to pure CO2 gas, showing a consistent response and recovery behaviour. The resistance of the double-layer graphene decreases linearly with increase of the concentration of pure CO2 gas. Density functional theory simulations indicate that double-layer graphene has a weaker gas response compared to single-layer graphene, which is in agreement with our experimental data. Our investigations contribute to improved understanding of the humidity and CO2 gas sensing properties of double-layer graphene which is important for realizing viable graphene-based gas sensors in the future.

  • 5.
    Fu, Qilin
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Industriell produktion, Maskin- och processteknologi. Plasmatrix Materials AB, Sweden.
    Rashid, Md Masud-Ur
    KTH, Skolan för industriell teknik och management (ITM), Industriell produktion, Maskin- och processteknologi. Plasmatrix Materials AB, Sweden.
    Nicolescu, Cornel-Mihai
    KTH, Skolan för industriell teknik och management (ITM), Industriell produktion.
    Toth, Geza
    et al.,
    High dynamic stiffness mechanical structures with nanostructured composite coatings deposited by high power impulse magnetron sputtering2016Inngår i: Carbon, ISSN 0008-6223, E-ISSN 1873-3891, Vol. 98, s. 24-33Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Nanostructured Cu:CuCNx composite coatings with high static and dynamic stiffness were synthesized by means of plasma-enhanced chemical vapor deposition (PECVD) combined with high power impulse magnetron sputtering (HiPIMS). Scanning electron microscope (SEM) images and energy-dispersive X-ray spectroscopy (EDS) mapping from cross-sectioned samples reveals a multi-layered nanostructure enriched in Cu, C, N, and O in different ratios. Mechanical properties of the coatings were investigated by Vickers micro-indention and model tests. It was observed that copper inclusions as well as copper interlayers in the CNx matrix can increase mechanical damping by up to 160%. Mechanical properties such as hardness, elastic modulus and loss factor were significantly improved by increasing the discharge power of the sputtering process. Moreover the coatings loss modulus was evaluated on the basis of indentation creep measurements under room temperature. The coating with optimum properties exhibited loss modulus of 2.6 GPa. The composite with the highest damping loss modulus were applied on the clamping region of a milling machining tool to verify their effect in suppressing regenerative tool chatter. The high dynamic stiffness coatings were found to effectively improve the critical stability limit of a milling tool by at least 300%, suggesting a significant increase of the dynamic stiffness.

  • 6.
    Hussami, Linda
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Oorganisk kemi.
    Corkery, Robert W.
    Institution of Surface Chemistry.
    Kloo, Lars
    KTH, Skolan för kemivetenskap (CHE), Kemi, Oorganisk kemi.
    Polyhedral carbon nanofoams with minimum surface area partitions produced using silica nanofoams as templates2010Inngår i: Carbon, ISSN 0008-6223, E-ISSN 1873-3891, Vol. 48, nr 11, s. 3121-3130Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Polyhedral silica nanofoam (PNF-SiO2) analogues of dry soap froths with minimal surface area were used as templates for making polyhedral carbon nanofoams (PNF-C). Furfuryl alcohol or triblock copolymers were used as carbon sources. The volume of carbon precursor relative to the internal pore volume of PNF-SiO2's was systematically varied between 50% and 100% in order to investigate the effect of filling fraction on internal structure of the corresponding PNF-C's. Transmission electron microscopy, small-angle X-ray scattering and nitrogen physisorption were used to characterize the samples. To aid the interpretation of the experimental data, a model for X-ray scattering from spherical shells was used to approximate scattering from the polyhedral foam cells. PNF-C's cast from the PNF-SiO2's, displayed the characteristic Plateau borders of minimal surface area foams defining interconnected, slit-like pore systems at all filling fractions. At relatively high filling fractions, inverse foam structures were obtained with the slit-like pores systems interpenetrating aggregated, close-packed, relatively low density polyhedral carbon nanoparticles co-joined by carbon struts. At relatively low filling fractions, polyhedral carbon nanofoams with relatively thin, fused double-wall structures and interconnected polyhedral pore systems were obtained.

  • 7.
    Jacques, Eric
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Hellqvist Kjell, Maria
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Zenkert, Dan
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    The effect of lithium-intercalation on the mechanical properties of carbon fibres2014Inngår i: Carbon, ISSN 0008-6223, E-ISSN 1873-3891, Vol. 68, s. 725-733Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Carbon fibres (CFs) can be used as lightweight structural electrodes since they have high specific tensile stiffness and ultimate tensile strength (UTS), and high lithium (Li)-intercalation capability. This paper investigates the relationship between the amount of intercalated Li and the changes induced in the tensile stiffness and UTS of polyacrylonitrile-based CF tows. After a few electrochemical cycles the stiffness was not degraded and independent of the measured capacity. A drop in the UTS of lithiated CFs was only partly recovered during delithiation and clearly larger at the highest measured capacities, but remained less than 40% at full charge. The reversibility of this drop with the C-rate and measured capacity supports that the fibres are not damaged, that some Li is irreversibly trapped in the delithiated CFs and that reversible strains develop in the fibre. However, the drop in the strength does not vary linearly with the measured capacity and the drop in the ultimate tensile strain remains lower than the CF longitudinal expansion at full charge. These results suggest that the loss of strength might relate to the degree of lithiation of defectives areas which govern the tensile failure mode of the CFs.

  • 8.
    Jacques, Eric
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Kjell, Maria
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Zenkert, Dan
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Behm, Mårten
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Expansion of carbon fibres induced by lithium intercalation for structural electrode applications2013Inngår i: Carbon, ISSN 0008-6223, E-ISSN 1873-3891, Vol. 59, s. 246-254Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Carbon fibres (CFs) can work as lightweight structural electrodes in CF-reinforced composites able to store energy as lithium (Li)-ion batteries. The CF has high stiffness and strength-to-weight ratios and a carbonaceous microstructure which enables Li intercalation. An innovative in situ technique for studying the longitudinal expansion of the CF and the relationship with the amount of intercalated Li is described in the present paper. The polyacrylonitrile-based CFs, T800H and unsized IMS65, were chosen for their electrochemical storage capacities. It was found that the CF expands during lithiation and contracts during delithiation. At the first electrochemical cycle, the expansion is partly irreversible which supports that the first-cycle capacity loss partly relates to Li trapped in the CF structure. For the following cycles, the capacity and the expansion are reversible. The expansion, which might relate to tensile stress, increases up to 1% as the measured capacity approaches the theoretical limit of 372 mAh/g for Li storage in graphite. Minor additional expansions due to the uneven distribution of intercalated Li in the CF structure were measured before and after lithiations. Using scanning electron microscope images the transverse expansion of fully lithiated CFs was estimated to about 10% of the cross-section area.

  • 9.
    Li, Jiantong
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Ye, Fei
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Vaziri, Sam
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Muhammed, Mamoun
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Lemme, Max C.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    A simple route towards high-concentration surfactant-free graphene dispersions2012Inngår i: Carbon, ISSN 0008-6223, E-ISSN 1873-3891, Vol. 50, nr 8, s. 3113-3116Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A simple solvent exchange method is introduced to prepare high-concentration and surfactant-free graphene liquid dispersion. Natural graphite flakes are first exfoliated into graphene in dimethylformamide (DMF). DMF is then exchanged by terpineol through distillation, relying on their large difference in boiling points. Graphene can then be concentrated thanks to the volume difference between DMF and terpineol. The concentrated graphene dispersions are used to fabricate transparent conductive thin films, which possess comparable properties to those prepared by more complex methods.

  • 10. Lippert, G.
    et al.
    Dabrowski, J.
    Yamamoto, Y.
    Herziger, F.
    Maultzsch, J.
    Lemme, Max C.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Mehr, W.
    Lupina, G.
    Molecular beam growth of micrometer-size graphene on mica2013Inngår i: Carbon, ISSN 0008-6223, E-ISSN 1873-3891, Vol. 52, s. 40-48Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We demonstrate molecular beam growth of graphene on biotite mica substrates at temperatures below 1000 °C. As indicated by optical and atomic force microscopy, evaporation of carbon from a high purity solid-state source onto biotite surface results in the formation of single-, bi-, and multilayer graphene with size in the micrometer regime. It is shown that the graphene grown directly on mica surface is of very high crystalline quality with the defect density below the threshold detectable by Raman spectroscopy. The interaction between graphene and the mica substrate is studied by comparison of the Raman spectroscopy and atomic force microscopy data with the corresponding results obtained for graphene flakes mechanically exfoliated onto biotite substrates. Experimental insights are combined with density functional theory calculations to propose a model for the initial stage of the van der Waals growth of graphene on mica surfaces. This work provides hints on how the direct growth of high quality graphene on insulators can be realized in general without exceeding the thermal budget limitations of Si technologies.

  • 11.
    Lopez Cabezas, Ana
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektroniksystem. KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, VinnExcellence Center for Intelligence in Paper and Packaging, iPACK.
    Feng, Yi
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektroniksystem. KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, VinnExcellence Center for Intelligence in Paper and Packaging, iPACK.
    Zheng, Li-Rong
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektroniksystem. KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, VinnExcellence Center for Intelligence in Paper and Packaging, iPACK.
    Zhang, Zhi-Bin
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektroniksystem. KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, VinnExcellence Center for Intelligence in Paper and Packaging, iPACK. Department of Engineering Sciences, Uppsala University.
    Thermal ageing of electrical conductivity in carbon nanotube/polyaniline composite films2013Inngår i: Carbon, ISSN 0008-6223, E-ISSN 1873-3891, Vol. 59, s. 270-277Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The influence of carbon nanotubes on the thermal ageing effect of the electrical conductivity of composite thin films is presented. The composite thin films comprise carbon nanotube/polyaniline nanofibers. When subject to thermal treatment, the presence of nanotubes retards the loss of dopants from the polyaniline and enhances the thermal stability in electrical conductivity of the composite thin films. Specifically, an increase in temperature for the conductivity degradation and a significant reduction in the rate of the conductivity degradation of the composite thin films are observed. Upon prolonged heating, the composite thin films exhibit relative large conductivity at high nanotube content, while the polyaniline thin films become insulating.

  • 12.
    Ma, Yong
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Teoretisk kemi och biologi.
    Lin, J.
    Song, X. -N
    Wang, C. -K
    Hua, W.
    Luo, Yi
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Teoretisk kemi och biologi.
    Local structures of nitrogen doped graphdiynes determined by computational X-ray spectroscopy2019Inngår i: Carbon, ISSN 0008-6223, E-ISSN 1873-3891, Vol. 149, s. 672-678Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Nitrogen doping is an important method to modulate electronic structure of two-dimensional carbon materials. The properties of the doped systems are heavily dependent on the local structure of nitrogen dopants involved, which are often determined by experimental X-ray photoelectron spectra (XPS) and near-edge X-ray absorption fine-structure (NEXAFS) at the nitrogen K-edge. In the present work, the N1s XPS and NEXAFS spectra of nitrogen-doped graphdiynes have been accurately calculated at the density functional theory level. Five representative nitrogen-dopants in graphdiynes, namely [pyridinic, amino, graphitic, and two sp-hybridized N (sp-N-1 and sp-N-2) local structures], are fully examined, from which all experimental features could be correctly assigned. The calculated results can be used to determine the ratio of different nitrogen dopants in graphdiyne at different elevated temperatures reported in previous experiments. Our findings provide the basic references for structure determination of nitrogen doped graphdiyne and new understanding of the underlying structure-property relationships.

  • 13.
    Mittal, Nitesh
    et al.
    Indian Institute of Technology, India.
    Deva, Dinesh
    Kumar, Rudra
    Sharma, Ashutosh
    Exceptionally robust and conductive superhydrophobic free-standing films of mesoporous carbon nanocapsule/polymer composite for multifunctional applications2015Inngår i: Carbon, ISSN 0008-6223, E-ISSN 1873-3891, Vol. 93, nr 8, s. 492-501Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A novel mesoporous carbon nanocapsule (MCC)/polyvinylidene fluoride (PVDF) polymer composite based free-standing film with multifunctional properties is fabricated by a facile solution approach that is appropriate for dip coating, brush-on and spray applications. The MCC/PVDF composite film exhibits superhydrophobic properties with a water contact angle of approximately 160° and a sliding angle of 5°. The films have a high thermal stability (up to 350 °C in oxidative atmosphere) and are also electrically conductive (tunable from ∼10−3 S m−1 to 10−2 S m−1). The superhydrophobicity is retained even in highly corrosive acidic and basic conditions (pH 1.29–13.54, concentrated HNO3 exposure and ammonium hydroxide solution), as well in a wide humidity range (35–83%). The mesoporous carbon containers (∼100 nm–1 μm size) also provide an interesting platform for encapsulating a variety of functional nanomaterials and activate release, thereby adding to the multi-functionality of the superhydrophobic conductive films of exceptional environmental stability, mechanical strength (∼0.1 GPa) and flexibility.

  • 14. Myglovets, M.
    et al.
    Poddubnaya, O. I.
    Sevastyanova, Olena
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi.
    Lindström, Mikael E.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi.
    Gawdzik, B.
    Sobiesiak, M.
    Tsyba, M. M.
    Sapsay, V. I.
    Klymchuk, D. O.
    Puziy, A. M.
    Preparation of carbon adsorbents from lignosulfonate by phosphoric acid activation for the adsorption of metal ions2014Inngår i: Carbon, ISSN 0008-6223, E-ISSN 1873-3891, Vol. 80, s. 771-783Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Activated carbons were prepared from sodium lignosulfonate by phosphoric acid activation at carbonization temperatures of 400-1000 degrees C. The resulting materials were characterized with regard to their surface area, pore volume, pore size distribution, distribution of surface groups and ability to adsorb copper ions. Activated carbons were characterized by nitrogen adsorption, scanning electron microscopy, Fourier transform infrared spectroscopy and thermal gravimetric analyses. The results indicate that with increasing carbonization temperature, the surface area decreased from 770 m(2)/g at 400 degrees C to 180 m(2)/g at 700 degrees C and increased at higher temperatures to 1370 m(2)/g at 1000 degrees C. The phosphorus content peaked at 11% for carbon obtained by carbonization at 800 degrees C. Potentiometric titration revealed the acidic character of all the phosphoric acid-activated carbons, which were found to have total concentrations of surface groups of up to 3.3 mmol/g. The carbons showed a high adsorption capacity for copper ions even at pH values as low as 2.

  • 15. Saidi, W. A.
    et al.
    Norman, Patrick
    Linköping University, Sweden.
    Probing single-walled carbon nanotube defect chemistry using resonance Raman spectroscopy2014Inngår i: Carbon, ISSN 0008-6223, E-ISSN 1873-3891, Vol. 67, s. 17-26Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Using state-of-the-art time-dependent density functional theory and employing the complex polarization propagator theory, we compute the UV-vis absorption and resonance Raman (RR) spectra of pristine and H- and F-decorated single-walled carbon nanotubes (SWCNTs).We find that H- and F-functionalization brightens a low energy exciton that couples the SWCNT local-defect chemistry to its extended p network. Surprisingly, the energy of the strongly light absorbing φ- φ* excitation (SS 11) and the Raman shift of the radial breathing mode (RBM) are not very sensitive to the presence of the defects, and to a lesser degree their type. In contrast, the RR intensities of the RBM resonance profile are reduced by two orders of magnitude upon functionalization due to changes in the dynamic polarizabilities. Additionally, the resonance profile shows sensitivity to the defect chemistry where the Hfunctionalized CNTs have a factor ∼4 larger intensities than F-functionalized CNTs in the near resonance region. Despite the differences in the nature of the local defects, our findings are in good agreement with recent experiments on individual SWCNTs with well controlled topological defects. The study shows that photoluminescence is not sensitive to low concentrations of defects, but RR spectroscopy provides a powerful ultra-sensitive tool to identify and categorize CNT defects.

  • 16. Wang, Bo-Yao
    et al.
    Wang, Hsiaotsu
    Chen, Ling-Yen
    Hsueh, Hung-Chung
    Li, Xin
    Guo, Jinghua
    Luo, Yi
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Chiou, Jau-Wern
    Wang, Wei-Hua
    Wang, Po-Hsiang
    Chen, Kuei-Hsien
    Chen, Yen-Chih
    Chen, Li-Chyong
    Chen, Chia-Hao
    Wang, Jian
    Pong, Way-Faung
    Nonlinear bandgap opening behavior of BN co-doped graphene2016Inngår i: Carbon, ISSN 0008-6223, E-ISSN 1873-3891, Vol. 107, s. 857-864Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We have demonstrated a nonlinear behavior for the bandgap opening of doped graphene by controlling the concentration of B and N co-dopants. X-ray absorption and emission spectra reveal that the bandgap increases from 0 to 0.6 eV as the concentration of BN dopants is increased from 0 to 6%, while the bandgap closes when the doping concentration becomes 56%. This nonlinear behavior of bandgap opening of the BN-doped graphene depending on the BN concentrations is consistent with the valenceband photoemission spectroscopic measurements. The spatially resolved B, N and C K-edge scanning transmission x-ray microscopy and their x-ray absorption near- edge structure spectra all support the scenario of the development of h-BN-like domains at high concentrations of BN. Ab initio calculation, by taking into account of the strong correlation between the bandgap and the geometry/concentration of the dopant, has been performed with various BN-dopant nano-domains embedded in the graphene monolayer to verify the unique bandgap behavior. Based on the experimental measurements and ab initio calculation, we propose the progressive formation of a phase-separated zigzag-edged BN domain from BN quantum dots with increasing BN-dopant concentration to explain the extraordinary nonlinear behavior of bandgap opening of BN-doped graphene sheets. This study reveals a new way to engineer the bandgap of low-dimensional systems.

  • 17. Yao, Mingguang
    et al.
    Stenmark, Patrik
    Abou-Hamad, Edy
    Nitze, Florian
    Qin, Jian
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Goze-Bac, Christophe
    Wågberg, Thomas
    Confined adamantane molecules assembled to one dimension in carbon nanotubes2011Inngår i: Carbon, ISSN 0008-6223, E-ISSN 1873-3891, Vol. 49, nr 4, s. 1159-1166Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We have encapsulated adamantane (C10H16) in single- and multi-walled carbon nanotubes. Adamantane is a high symmetry cage like molecule with point group symmetry T-d and can be considered as a hydrogen-terminated diamond fragment. We confirmed and identified the successful filling by high resolution transmission electron microscopy, C-13 nuclear magnetic resonance, infrared and Raman spectroscopy. C-13 nuclear magnetic resonance of the adamantane filled nanotubes reveals that the adamantane molecules stop rotating after encapsulation. A blue-shift of the Raman active radial breathing modes of the carbon nanotubes supports this and suggests a significant interaction between encapsulated adamantane molecules and the single wall nanotubes. The encapsulated adamantane molecules exhibit red shifted infrared C-H vibration modes which we assign to a slight elongation of the C-H bonds. We observe both a nanotube diameter dependence of the adamantane filling ratio and a release rate of adamantane from the CNTs that depends on the CNT diameters.

  • 18.
    Zakharchenko, Konstantin V.
    et al.
    KTH, Centra, Nordic Institute for Theoretical Physics NORDITA. Stockholm University, Sweden.
    Balatsky, Alexander V.
    KTH, Centra, Nordic Institute for Theoretical Physics NORDITA. Institute for Materials Science, Los Alamos, USA .
    Controlled healing of graphene nanopores2014Inngår i: Carbon, ISSN 0008-6223, E-ISSN 1873-3891, Vol. 80, s. 12-18Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Nanopores - nanometer-size channels hold significant promise for numerous applications: DNA sequencing, sensing, biosensing and molecular detectors, and catalysis and water desalination. However, these applications require accurate control over the size of the nanopores. Since graphene is often mentioned as a promising material to host nanopores, we have performed realistic computer simulation studies of regrowth and healing of graphene nanopores of different sizes ranging from 30 to 5 angstrom. Our simulations clearly point to at least two distinct healing mechanisms for graphene sheets: edge attachment (where carbons are attached to the edges of the graphene sheet/pore) and direct insertion (where individual atoms insert directly into a sheet of graphene, even in the absence of the edges). The insertion mechanism is a surprising prediction that points to the growth process that would be operational in pristine graphene. We have uncovered an unusual dependence in the speed of nanopore regrowth and the structure of "healed" areas as a function of its size in a wide range of temperatures. Our findings point to significantly more complicated pathways for graphene annealing. They also provide an important enabling step in the development of graphene-based devices for numerous applications in nanotechnology. Our results suggest the possibility to control the final size of healed nanopore by terminating the annealing at a prescribed time dependent on the temperature.

  • 19. Zhang, Hui
    et al.
    Li, Xin
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Zhang, Duo
    Zhang, Liang
    Kapilashrami, Mukes
    Sun, Tao
    Glans, Per-Anders
    Zhu, Junfa
    Zhong, Jun
    Hu, Zheng
    Guo, Jinghua
    Sun, Xuhui
    Comprehensive electronic structure characterization of pristine and nitrogen/phosphorus doped carbon nanocages2016Inngår i: Carbon, ISSN 0008-6223, E-ISSN 1873-3891, Vol. 103, s. 480-487Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The electronic structures of carbon nanocages (CNCs) and nitrogen/phosphorus doped carbon nanocages (N-CNCs/P-CNCs) have been studied by X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS), X-ray emission spectroscopy (XES) and resonant X-ray emission spectroscopy (RXES). The doping configurations for N/P dopants are identified from the experiments. The results have shown that there are three major doping configurations for nitrogen but only one doping configuration for phosphorus. The nitrogen doping reveals the complex coexistence of graphite-like, pyridine-like and pyrrole-like configurations that are proved by density functional theory (DFT) simulations, while the phosphorus doping presents only the "graphite-like" configuration. The different configuration profiles result in less atomic structure ordering of N-CNCs than that of P-CNCs. XAS spectra obtained from both surface and bulk sensitive detection suggest different chemical environments between the interior and shell for all types of nanocages. The electronic structure modifications show significant difference between nitrogen and phosphorus doping from the DOS calculations. (C) 2016 Elsevier Ltd. All rights reserved.

  • 20. Zhong, Jun
    et al.
    Guo, Jinghua
    Gao, Bin
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi.
    Chiou, Jau-Wern
    Li, Jiong
    Chu, Wangsheng
    Pong, Way-Faung
    Chang, Chinglin
    Luo, Yi
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi.
    Wu, Ziyu
    Understanding the scattering mechanism of single-walled carbon nanotube based gas sensors2010Inngår i: Carbon, ISSN 0008-6223, E-ISSN 1873-3891, Vol. 48, nr 7, s. 1970-1976Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In the interaction between gas molecules with single-walled carbon nanotube (SWCNT) we show that as a result of collisions the gas scattering contributes with an important background signal and should be considered in SWCNT-based gas sensors. Experimental evidence of the collision-induced tube wall deformation is demonstrated using in situ X-ray absorption near-edge structure spectroscopy. Results support the occurrence of the scattering process and show how gas collisions may affect the electronic structure of SWCNTs.

  • 21. Zhong, Jun
    et al.
    Song, Li
    Meng, Jie
    Gao, Bin
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi.
    Chu, Wangsheng
    Xu, Haiyan
    Luo, Yi
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi.
    Guo, Jinghua
    Marcelli, Augusto
    Xie, Sishen
    Wu, Ziyu
    Bio-nano interaction of proteins adsorbed on single-walled carbon nanotubes2009Inngår i: Carbon, ISSN 0008-6223, E-ISSN 1873-3891, Vol. 47, nr 4, s. 967-973Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We applied X-ray absorption near edge structure (XANES) spectroscopy to investigate the adsorption of proteins onto single-walled carbon nanotubes (SWCNTs). Specific XANES spectral features such as peptide C=O bonds in proteins were recognized and found to be affected by the corresponding aromatic structure of SWCNTs. Experimental data combined with first-principle calculation of the investigated nano-complex allow the understanding of adsorption mechanism and reveal that an interface interaction occurs leading to precise structural distortions of proteins. The study also demonstrates that XANES is a powerful tool to characterize structural details of proteins at the interface of complex systems.

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