Graphene

Graphene is a one-atom-thick planar sheet of sp2-bondedcarbon atoms densely packed in a hexagonal honeycomb crystal lattice. Although graphene had been studied theoretically for decades, its actual existence wasn't proven until 2004, when Kostya Novoselov and Andrei Geim from the Manchester University managed to isolate a monolayer for the first time. In 2010 they were awarded the Nobel Prize.
In our group we are interested in exploring and exploiting some of the exceptional properties of graphene - at the moment we focus on mechanical and electrochemical alteration of its electronic structure and we try to observe the response to these changes by various methods, but mainly with Raman spectroscopy. We prepare our samples either ourselves by CVD or mechanical exfoliation.

Graphene Production

The large scale production of graphene for electronic devices relies on catalytic chemical vapor deposition (CVD). Therefore, main attention is dedicated to understand the mechanism of the graphene formation and also to control the growth. Nevertheless, in spite of many efforts put into the graphene CVD research, there are still many challenges to be solved. Cu or Ni are the most widely used...Read more

• Kalbac M., Frank O., Kavan L. Carbon 50(10), 3682-3687 (2012). DOI: 10.1016/j.carbon.2012.03.041
• Kalbac M., Frank O., Kong J., Sanchez-Yamagishi J., Watanabe K; Taniguchi T., Jarillo-Herrero P., Dresselhaus M.S., Journal of Physical Chemistry Letters 3(6), 796-799 (2012). DOI: 10.1021/jz300176a

Functionalization

2D materials are fascinating emerging materials with amazing features for an exhaustive range of fields. Tuning of the material’s properties is crucial to unlock the potential for each particular application. It can be realized by several methods,...Read more

 

• Drogowska, K.; Kovaříček, P.; Kalbáč, M. Chem. Eur. J. 201723 (17), 4073–4078. DOI: 10.1002/chem.201605385
• Plšek, J.; Kovaříček, P.; Valeš, V.; Kalbáč, M. Chem. Eur. J. 201723 (8), 1839–1845. DOI: 10.1002/chem.201604311
• Kovaříček, P.; Bastl, Z.; Valeš, V.; Kalbáč, M. Chem. Eur. J. 201622 (15), 5404–5408. DOI: 10.1002/chem.201504689

Mechanical deformation

Mechanical deformation is capable of modifying the crystal structure and in turn also the (opto)electronic structure of 2D materials both globally and locally. It is thus crucial to monitor and control the deformation for any envisioned application of these materials, in a way that ...Read more

 

Pacakova B., Verhagen T., Bousa M., Hübner U., Vejpravova J., Kalbac M., Frank O. Mastering the Wrinkling of Self-supported Graphene. Scientific Reports 7(1), 10003 (2017). DOI:10.1038/s41598-017-10153-z (OPEN ACCESS)
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del Corro E., Peña-Alvarez M.,Sato K., Morales-Garcia A., Bousa M., Mračko M., Kolman R.,Pacakova B., Kavan L., Kalbac M., Frank O.Fine tuning of optical transition energy of twisted bilayer graphene via interlayer distance modulation. Physical Review B 95(8), 085138 (2017). DOI:10.1103/PhysRevB.95.085138

 

Solar cells


The use of the 2D materials in different types of solar cells has been shown to improve some of the designs, or at least to provide an alternative to expensive materials in the others...Read more

 

• Kavan, L.; Yum, J.H., Graetzel, M.: Graphene Nanoplatelets Outperforming Platinum as the Electrocatalyst in Co-Bipyridine-Mediated Dye-Sensitized Solar Cells. Nano Letters 11(12), 5501-5506 (2011). DOI: 10.1021/nl203329c
• Kavan L.
, Yum J.H., Graetzel M. Optically Transparent Cathode for Co(III/II) Mediated Dye-Sensitized Solar Cells Based on Graphene Oxide. ACS Applied Materials & Interfaces 4(12), 6998-7005 (2012). DOI: 10.1021/am302253e

Sensors

In the Department of Low-dimensional Systems focus is also kept on sensorics. Graphene, carbon nanotubes and other nanocarbon material evince promising electronic and chemical properties which could be efficiently used in sensorics. Detection of ppm concentration of target gas species...Read more

 

• Blechta, M. Mergl, K. Drogowska, V. Valeš, M. Kalbáč, Sensors Actuators B Chem. 2016, 226, 299–304. DOI: 10.1016/j.snb.2015.11.130
P. Kovaříček, K. Drogowska, Z. Melníková Komínková, V. Blechta, Z. Bastl, D. Gromadzki, M. Fridrichová, M. Kalbáč, Carbon N. Y. 2017, 113, 33–39. DOI: 10.1016/j.carbon.2016.11.018

Energy Storage

Energy storage is one of the most important topics in today’s R&D, where carbon-based materials play an irreplaceable role. Graphite is widely used as intercalation material for anodes in Li-ion batteries...Read more

 

• Petrák V., Vlčková Živcová Z., Krýsová H., Frank O., Zukal A., Klimša L., Kopeček J., Taylor A., Kavan L., Mortet V. Fabrication of porous boron-doped diamond on SiO2 fiber templates. Carbon 114, 457-64 (2017). DOI: 10.1016/j.carbon.2016.12.012
• Bousa M., Frank O., Kavan L.
Progressive In Situ Reduction of Graphene Oxide Studied by Raman Spectroelectrochemistry: Implications for a Spontaneous Activation of LiFePO4 (Olivine).Electroanalysis 26(1), 57-61 (2014). DOI: 10.1002/elan.201300340

Magnetism and nanocarbons

Magnetism in carbon-based materials is in the spotlight of current science; however, still a matter of controversy.
While ferromagnetism has been confirmed in defected graphite, magnetism enthusiastically reported for carbon nanotubes was later excluded by synchrotron radiation experiments, which revealed presence of metallic magnetic impurities. The magnetic myths also rised for graphene, for which several scenarios of apparently exotic magnetic order appeared, without a serious experimental evidence and relevant theoretical support. We aim to fair approach to this issue by employing ultra-sensitive micro-squid and spin resonance techniques, as well as by using spin-resolved AR PES, neutron scattering and synchrotron scattering methods, such as XMCD and LMD.

 

Enhanced Raman Spectroscopy


Enhanced Raman spectroscopy is a valuable tool for detection of low concentrations of molecules. For this reason, surface-enahnced Raman spectroscopy (SERS) it is a suitable method for inspecting functionalized graphene
. However, for a proper understanding...Read more

 

• P. Kovaříček, Z. Bastl, V. Valeš, and M. Kalbac, Chem. - A Eur. J. 22, 5404–5408 (2016).
• J. Ek Weis, S. Costa, O. Frank, M. Fridrichová, B. Vlčková, J. Vejpravova, and M. Kalbac, J. Phys. Chem. C, acs.jpcc.7b02585 (2017).
• J. E. Weis, J. Vejpravova, T. Verhagen, Z. Melnikova, S. Costa, and M. Kalbac,  J. Raman Spectrosc. (2017).

 

Spectroelectrochemistry

One of the important features of graphene and related low-dimensional objects is the relatively simple tunability of their electronic structure, an asset that extends the usability of these materials even further beyond present experience. A direct injection of charge carriers into the conduction or valence bands, that is, doping, represents a viable way of shifting the Fermi level. In particular, electrochemical doping should be the method of choice,...Read more

• Frank O., Dresselhaus M.S., Kalbac M. Raman spectroscopy and In-situ Raman spectroelectrochemistry of isotopically engineered graphene systems. Accounts of Chemical Research 48(1), 111-118 (2015). DOI: 10.1021/ar500384p
• Kalbac, M.; Reina-Cecco, A., Farhat, H., Kong, J., Kavan, L.; Dresselhaus, M. S.: The Influence of Strong Electron and Hole Doping on the Raman Intensity of Chemical Vapor-Deposition Graphene. ACS Nano 4(10), 6055-6063 (2010). DOI: 10.1021/nn1010914