One research topic focusses on functional materials based on biopolymers such as cellulose. By an appropriate surface functionalization of the cellulose containing carrier material with inorganic molecules, small organic or biomolecules these materials can be tuned to become applicable as sensoric devices, in fluid flow control or optical devices. The Gutmann’s group is developing and applying analytical techniques to identify the surface functionalization and to characterize the structure of these disordered materials at the mesoscopic length scale. As important tool they use a combination of solid-state NMR and Dynamic Nuclear Polarization techniques.
[1] Gutmann, T.*, Kumari, B., Zhao, L., Breitzke, H.; Schöttner, S., Rüttiger, C., Gallei, M.*, DNP Signal Amplification as Sensitive Probe for Specific Functionalization of Complex Paper Substrates, J. Phys. Chem. C 121, (2017), 3896-3903. DOI: 10.1021/acs.jpcc.6b11751
[2] Dubois, C., Herzog, N., Rüttiger, C., Geissler, A., Grange, E., Kunz, U., Kleebe, H.-J., Biesalski, M., Meckel, T., Gutmann, T., Gallei, M., Andrieu-Brunsen, A.*, Fluid Flow Programming in Paper-Derived Silica-Polymer Hybrids, Langmuir 33, (2017), 332–339. DOI: 10.1021/acs.langmuir.6b03839
3] Höfler, M. V., Hoinka, N., Schäfer, T., Horn, M., Aussenac, F., Fuhrmann-Lieker, T.*, Gutmann, T.*, Light Amplification Materials based on Biopolymers doped with Dye Molecules – Structural Insights from 15N and 13C Solid state Dynamic Nuclear Polarization. J. Phys. Chem C 125, (2021), 21550–21558. DOI: 10.1021/acs.jpcc.1c06737
Very recently in the framework of the EU project SIMBA (www.simba-h2020.eu), the group started the investigation of sodium /sodium Ion battery components employing ex-situ and operando solid-state NMR. Questions such as the structural intercalation of sodium in electrode materials in solid-phase battery systems are addressed. Furthermore, structural changes of the materials will be investigated under working conditions to understand processes during cycling that may affect the efficiency and life time of the energy storage systems.
Sic, E., Melzi d'Eril, M., Schutjajew, K., Graczyk-Zajac, M., Breitzke, H., Riedel, R., Oschatz, M., Gutmann, T*, Buntkowsky, G.*, SiCN Ceramics as Electrode Materials for Sodium/Sodium Ion Cells – Insights from 23Na In-situ Solid-State NMR. Batter. Supercaps, (2022), e202200066. DOI:10.1002/batt.202200066
A second research topic deals with polymeric nanoparticles containing core-shell architectures which can be employed to prepare optical films. For these particles analytical techniques are developed and applied to identify the surface functionalization of the particles as well as to determine the structural crosslinking in the polymer forming the shell independent from the core of the particles. A powerful approach here is the use of selective signal enhancement provided by DNP enhanced solid-state NMR for which suitable sample preparations have to be developed.
[1] Schäfer, T., Vowinkel, S., Breitzke, H., Gallei, M., Gutmann, T.*, Selective DNP Signal Amplification to Probe Structures of Core-Shell Polymer Hybrid Nanoparticles. J. Phys. Chem. C 123, (2019), 644-652. DOI: 10.1021/acs.jpcc.8b07969
[2] Scheid, D., Stock, D., Winter, T., Gutmann, T.*, Dietz, C., Gallei, M.*, The Pivotal Step of Nanoparticle Functionalization for the Preparation of Functional and Magnetic Hybrid Opal Films, J. Mater. Chem. C 4, (2016), 2187-2196. DOI:10.1039/c5tc04388c
Next to polymeric nanoparticles the group is interested in organic polymers containing paramagnetic centers as they can by employed in energy storage systems or in catalysis. Here we focus to broaden the applicability of solid-state NMR techniques including dynamic nuclear polarization to characterize such materials. In future we would further extent the approach to study such materials in operando under the conditions they are used in energy storage systems or in catalysis.
[1] Grätz, S., de Oliveira Jr., M., Gutmann, T.*, Borchardt, L.*, A comprehensive approach for the Characterization of Porous Polymers by 13C and 15N Dynamic Nuclear Polarization NMR Spectroscopy. Phys. Chem. Chem. Phys. 22, (2020), 23307-23314. DOI: 10.1039/D0CP04010J
[2] Krusenbaum, A., Geisler, J., Kraus, F. J. L., Grätz, S., Höfler, M. V., Gutmann, T., Borchardt, L.* The Mechanochemical Friedel Crafts Polymerization as a Solvent-free Cross-linking Approach towards Microporous Polymers. J. Polym. Sci. 60, (2022), 62-71. DOI: 10.1002/pol.20210606
A third research area focusses on heterogeneous catalysts. As examples supported metal nanoparticles as well as porous catalysts are investigated, which are of high interest in technical reactions such as in CO oxidation, hydrogenation, Haber Bosch or in exhaust gas purification processes such as NOx reduction. Our interest is to identify catalytic sites as well as to get insights into the surface chemistry of these catalyst systems, which is the basic step to optimize them for technical applications.
[1] Klimavicius, V., Neumann, S., Kunz, S., Gutmann, T.*, Buntkowsky, G.* Room temperature CO oxidation catalysed by supported Pt nanoparticles revealed by solid-state NMR and DNP spectroscopy. Catal. Sci. Technol. 9, (2019), 3743–3752. DOI: 10.1039/c9cy00684b
[2] de Oliveira Jr, M., Seeburg, D., Weiss, J., Wohlrab, S., Buntkowsky, G.*, Bentrup, U.*, Gutmann, T.* Structural characterization of vanadium environments in MCM-41 molecular sieve catalysts by solid state 51V NMR. Catal. Sci. Technol. 9, (2019), 6180–6190. DOI: 10.1039/C9CY01410A
[3] Rothermel, N., Limbach, H.-H., del Rosal, I., Poteau, R.*, Mencia, G., Chaudret, B., Buntkowsky, G.*, Gutmann, T.* Surface reactions of ammonia on ruthenium nanoparticles revealed by 15N and 13C solid-state NMR. Catal. Sci. Technol. 11, (2021), 4509 – 4520. DOI: 10.1039/D0CY02476G
