--- _id: '63991' abstract: - lang: eng text: A series of 1 and 2 nm sized platinum nanoparticles (Pt-NPs) deposited on different support materials, namely, gamma-alumina (gamma-Al2O3), titanium dioxide (TiO2), silicon dioxide (SiO2) and fumed silica are investigated by solid-state NMR and dynamic nuclear polarization enhanced NMR spectroscopy (DNP). DNP signal enhancement factors up to 170 enable gaining deeper insight into the surface chemistry of Pt-NPs. Carbon monoxide is used as a probe molecule to analyze the adsorption process and the surface chemistry on the supported Pt-NPs. The studied systems show significant catalytic activity in carbon monoxide oxidation on their surface at room temperature. The underlying catalytic mechanism is the water-gas shift reaction. In the case of alumina as the support the produced CO2 reacts with the surface to form carbonate, which is revealed by solid-state NMR. A similar carbonate formation is also observed when physical mixtures of neat alumina with silica, fumed silica and titania supported Pt-NPs are studied. author: - first_name: V. full_name: Klimavicius, V. last_name: Klimavicius - first_name: S. full_name: Neumann, S. last_name: Neumann - first_name: S. full_name: Kunz, S. last_name: Kunz - first_name: Torsten full_name: Gutmann, Torsten id: '118165' last_name: Gutmann - first_name: G. full_name: Buntkowsky, G. last_name: Buntkowsky citation: ama: 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. Catalysis Science & Technology. 2019;9(14):3743–3752. doi:10.1039/c9cy00684b apa: Klimavicius, V., Neumann, S., Kunz, S., Gutmann, T., & Buntkowsky, G. (2019). Room temperature CO oxidation catalysed by supported Pt nanoparticles revealed by solid-state NMR and DNP spectroscopy. Catalysis Science & Technology, 9(14), 3743–3752. https://doi.org/10.1039/c9cy00684b bibtex: '@article{Klimavicius_Neumann_Kunz_Gutmann_Buntkowsky_2019, title={Room temperature CO oxidation catalysed by supported Pt nanoparticles revealed by solid-state NMR and DNP spectroscopy}, volume={9}, DOI={10.1039/c9cy00684b}, number={14}, journal={Catalysis Science & Technology}, author={Klimavicius, V. and Neumann, S. and Kunz, S. and Gutmann, Torsten and Buntkowsky, G.}, year={2019}, pages={3743–3752} }' chicago: 'Klimavicius, V., S. Neumann, S. Kunz, Torsten Gutmann, and G. Buntkowsky. “Room Temperature CO Oxidation Catalysed by Supported Pt Nanoparticles Revealed by Solid-State NMR and DNP Spectroscopy.” Catalysis Science & Technology 9, no. 14 (2019): 3743–3752. https://doi.org/10.1039/c9cy00684b.' ieee: 'V. Klimavicius, S. Neumann, S. Kunz, T. Gutmann, and G. Buntkowsky, “Room temperature CO oxidation catalysed by supported Pt nanoparticles revealed by solid-state NMR and DNP spectroscopy,” Catalysis Science & Technology, vol. 9, no. 14, pp. 3743–3752, 2019, doi: 10.1039/c9cy00684b.' mla: Klimavicius, V., et al. “Room Temperature CO Oxidation Catalysed by Supported Pt Nanoparticles Revealed by Solid-State NMR and DNP Spectroscopy.” Catalysis Science & Technology, vol. 9, no. 14, 2019, pp. 3743–3752, doi:10.1039/c9cy00684b. short: V. Klimavicius, S. Neumann, S. Kunz, T. Gutmann, G. Buntkowsky, Catalysis Science & Technology 9 (2019) 3743–3752. date_created: 2026-02-07T15:47:21Z date_updated: 2026-02-17T16:16:33Z doi: 10.1039/c9cy00684b extern: '1' intvolume: ' 9' issue: '14' keyword: - Chemistry - gamma-alumina - hydrogenation - silica - c-13 - interactions - metal-catalysts - particle-size - platinum nanoparticles - sites - surface - water-gas shift language: - iso: eng page: 3743–3752 publication: Catalysis Science & Technology publication_identifier: issn: - 2044-4753 status: public title: Room temperature CO oxidation catalysed by supported Pt nanoparticles revealed by solid-state NMR and DNP spectroscopy type: journal_article user_id: '100715' volume: 9 year: '2019' ... --- _id: '64053' abstract: - lang: eng text: The utilization and preparation of functional hybrid films for optical sensing applications and membranes is of utmost importance. In this work, we report the convenient and scalable preparation of self-crosslinking particle-based films derived by directed self-assembly of alkoxysilane-based cross-linkers as part of a core-shell particle architecture. The synthesis of well-designed monodisperse core-shell particles by emulsion polymerization is the basic prerequisite for subsequent particle processing via the melt-shear organization technique. In more detail, the core particles consist of polystyrene (PS) or poly(methyl methacrylate) (PMMA), while the comparably soft particle shell consists of poly(ethyl acrylate) (PEA) and different alkoxysilane-based poly(methacrylate)s. For hybrid film formation and convenient self-cross-linking, different alkyl groups at the siloxane moieties were investigated in detail by solid-state Magic-Angle Spinning Nuclear Magnetic Resonance (MAS, NMR) spectroscopy revealing different crosslinking capabilities, which strongly influence the properties of the core or shell particle films with respect to transparency and iridescent reflection colors. Furthermore, solid-state NMR spectroscopy and investigation of the thermal properties by differential scanning calorimetry (DSC) measurements allow for insights into the cross-linking capabilities prior to and after synthesis, as well as after the thermally and pressure-induced processing steps. Subsequently, free-standing and self-crosslinked particle-based films featuring excellent particle order are obtained by application of the melt-shear organization technique, as shown by microscopy (TEM, SEM). author: - first_name: S. full_name: Vowinkel, S. last_name: Vowinkel - first_name: S. full_name: Paul, S. last_name: Paul - first_name: Torsten full_name: Gutmann, Torsten id: '118165' last_name: Gutmann - first_name: M. full_name: Gallei, M. last_name: Gallei citation: ama: Vowinkel S, Paul S, Gutmann T, Gallei M. Free-Standing and Self-Crosslinkable Hybrid Films by Core-Shell Particle Design and Processing. Nanomaterials. 2017;7(11):390. doi:10.3390/nano7110390 apa: Vowinkel, S., Paul, S., Gutmann, T., & Gallei, M. (2017). Free-Standing and Self-Crosslinkable Hybrid Films by Core-Shell Particle Design and Processing. Nanomaterials, 7(11), 390. https://doi.org/10.3390/nano7110390 bibtex: '@article{Vowinkel_Paul_Gutmann_Gallei_2017, title={Free-Standing and Self-Crosslinkable Hybrid Films by Core-Shell Particle Design and Processing}, volume={7}, DOI={10.3390/nano7110390}, number={11}, journal={Nanomaterials}, author={Vowinkel, S. and Paul, S. and Gutmann, Torsten and Gallei, M.}, year={2017}, pages={390} }' chicago: 'Vowinkel, S., S. Paul, Torsten Gutmann, and M. Gallei. “Free-Standing and Self-Crosslinkable Hybrid Films by Core-Shell Particle Design and Processing.” Nanomaterials 7, no. 11 (2017): 390. https://doi.org/10.3390/nano7110390.' ieee: 'S. Vowinkel, S. Paul, T. Gutmann, and M. Gallei, “Free-Standing and Self-Crosslinkable Hybrid Films by Core-Shell Particle Design and Processing,” Nanomaterials, vol. 7, no. 11, p. 390, 2017, doi: 10.3390/nano7110390.' mla: Vowinkel, S., et al. “Free-Standing and Self-Crosslinkable Hybrid Films by Core-Shell Particle Design and Processing.” Nanomaterials, vol. 7, no. 11, 2017, p. 390, doi:10.3390/nano7110390. short: S. Vowinkel, S. Paul, T. Gutmann, M. Gallei, Nanomaterials 7 (2017) 390. date_created: 2026-02-07T16:15:23Z date_updated: 2026-02-17T16:12:54Z doi: 10.3390/nano7110390 extern: '1' intvolume: ' 7' issue: '11' keyword: - Materials Science - Science & Technology - Other Topics - solid-state nmr - spectroscopy - catalysts - colloidal crystals - colloids - cross-linking - elastomeric opal films - emulsion polymerization - gamma-methacryloxypropyltrimethoxysilane - hybrid films - melt-shear organization - nanoparticles - particle - photons - polymers - processing - self-assembly - transition language: - iso: eng page: '390' publication: Nanomaterials publication_identifier: issn: - 2079-4991 status: public title: Free-Standing and Self-Crosslinkable Hybrid Films by Core-Shell Particle Design and Processing type: journal_article user_id: '100715' volume: 7 year: '2017' ... --- _id: '63920' abstract: - lang: eng text: Coordinatively unsaturated sites (CUS) present a key feature of alumina based catalysts as they are believed to act as Lewis-acid sites in heterogeneously catalyzed reactions. In the present study, the direct observation of active species on a fluoride-doped aluminum oxide catalyst is demonstrated. This new fluoride-doped aluminum oxide exhibits strong Lewis-acid sites and superior catalytic activity as compared to gamma-Al2O3. To emphasize the labile state of Lewis-acid sites, two distinctive states of the catalysts surface are addressed using H-1-Al-27 cross polarization (CP) MAS NMR. On the one hand, the highly dehydrated and active state after calcination at 700 degrees C and on the other hand the rehydrated and catalytically inactive surface (produced by contact to air) are probed. These experiments revealed the presence of significant amounts of coordinatively unsaturated sites in the form of 4-and 5-fold coordinated Al-sites on the highly dehydrated surface. In contrast to this, the rehydrated sample exhibited a severely restructured surface caused by the chemisorption of H2O which is ’constituted in a manner that was proposed in earlier models for gamma-Al2O3 surfaces. author: - first_name: L. full_name: Ahrem, L. last_name: Ahrem - first_name: G. full_name: Scholz, G. last_name: Scholz - first_name: Torsten full_name: Gutmann, Torsten id: '118165' last_name: Gutmann - first_name: B. full_name: Calvo, B. last_name: Calvo - first_name: G. full_name: Buntkowsky, G. last_name: Buntkowsky - first_name: E. full_name: Kemnitz, E. last_name: Kemnitz citation: ama: Ahrem L, Scholz G, Gutmann T, Calvo B, Buntkowsky G, Kemnitz E. Direct Observation of Coordinatively Unsaturated Sites on the Surface of a Fluoride-Doped Alumina Catalyst. Journal of Physical Chemistry C. 2017;121(22):12206–12213. doi:10.1021/acs.jpcc.7b02535 apa: Ahrem, L., Scholz, G., Gutmann, T., Calvo, B., Buntkowsky, G., & Kemnitz, E. (2017). Direct Observation of Coordinatively Unsaturated Sites on the Surface of a Fluoride-Doped Alumina Catalyst. Journal of Physical Chemistry C, 121(22), 12206–12213. https://doi.org/10.1021/acs.jpcc.7b02535 bibtex: '@article{Ahrem_Scholz_Gutmann_Calvo_Buntkowsky_Kemnitz_2017, title={Direct Observation of Coordinatively Unsaturated Sites on the Surface of a Fluoride-Doped Alumina Catalyst}, volume={121}, DOI={10.1021/acs.jpcc.7b02535}, number={22}, journal={Journal of Physical Chemistry C}, author={Ahrem, L. and Scholz, G. and Gutmann, Torsten and Calvo, B. and Buntkowsky, G. and Kemnitz, E.}, year={2017}, pages={12206–12213} }' chicago: 'Ahrem, L., G. Scholz, Torsten Gutmann, B. Calvo, G. Buntkowsky, and E. Kemnitz. “Direct Observation of Coordinatively Unsaturated Sites on the Surface of a Fluoride-Doped Alumina Catalyst.” Journal of Physical Chemistry C 121, no. 22 (2017): 12206–12213. https://doi.org/10.1021/acs.jpcc.7b02535.' ieee: 'L. Ahrem, G. Scholz, T. Gutmann, B. Calvo, G. Buntkowsky, and E. Kemnitz, “Direct Observation of Coordinatively Unsaturated Sites on the Surface of a Fluoride-Doped Alumina Catalyst,” Journal of Physical Chemistry C, vol. 121, no. 22, pp. 12206–12213, 2017, doi: 10.1021/acs.jpcc.7b02535.' mla: Ahrem, L., et al. “Direct Observation of Coordinatively Unsaturated Sites on the Surface of a Fluoride-Doped Alumina Catalyst.” Journal of Physical Chemistry C, vol. 121, no. 22, 2017, pp. 12206–12213, doi:10.1021/acs.jpcc.7b02535. short: L. Ahrem, G. Scholz, T. Gutmann, B. Calvo, G. Buntkowsky, E. Kemnitz, Journal of Physical Chemistry C 121 (2017) 12206–12213. date_created: 2026-02-07T08:56:18Z date_updated: 2026-02-17T16:19:24Z doi: 10.1021/acs.jpcc.7b02535 extern: '1' intvolume: ' 121' issue: '22' keyword: - al-27 nmr - characterization - Chemistry - cross-polarization - dynamic nuclear-polarization - eta-alumina - gamma-alumina - hydroxy fluorides - ions - Materials Science - pentacoordinated al3+ - Science & Technology - Other Topics - solid-state nmr - spectroscopic - structural insights language: - iso: eng page: 12206–12213 publication: Journal of Physical Chemistry C publication_identifier: issn: - 1932-7447 status: public title: Direct Observation of Coordinatively Unsaturated Sites on the Surface of a Fluoride-Doped Alumina Catalyst type: journal_article user_id: '100715' volume: 121 year: '2017' ...