Prof. Notker Rösch - Theoretical Chemistry
Research Interests
Prof. Notker Rösch’s research interests are the quantum chemical investigations of the electronic structure of complex systems by means of density functional methods. The development of electronic structure methods and their application to large molecules, metal clusters, cluster compounds as well as the studies of adsorption and catalysis at surfaces belong to the research focus of the group. Homo- and heterogeneous catalysis is explored with density functional methods using the Software package ParaGauss developed in the group. This includes the investigation of chemical processes on solid surfaces like the behavior of adsorbates at metal and oxide surfaces as well as in zeolite cavities. The aim is to create a deeper understanding of reaction mechanisms of catalytic processes at the atomic level, to give support for improvements in catalysis interpretation of experiments in the size range up to about 10 nm and for the synthesis of new material.
Selected Catalysis Research Topics
Catalysis on nanoclusters
Cluster as building blocks of nanostructured materials constitute an intermediate state of matter between molecules and solids. Physical and chemical properties of clusters are size-dependent and thus tunable. This fact is of particular interest in materials science, catalysis, and other fields of applied sciences such as nanoelectronics. The goals of research are to determine chemical properties, reactivity, composition, and structure of metal and oxide nanoparticles by applying density functional methods.
Methanol decomposition by Pd: Carbonaceous species are known to poison Pd catalysts in experiment. Methanol decomposition was modeled on a Pd79 cluster to investigate the C-O scission. A preference of carbonaceous species to bind at edges was found, explaining experimental findings.
De- and Hydrogenation over metals, on metal surfaces, and in zeolites
Oxide-supported transition metal particles are widely used as catalysts and as components of sensors, photovoltaic cells, and magnetic recording devices. Knowledge at the atomic level about the interactions of metal clusters with oxide supports is still far too scarce which notably hinders technological applications of these advanced materials. The group carries out systematic electronic structure calculations on these systems to fill that knowledge gap. An important result, obtained for Ir4 clusters in zeolites and substantiated for Rh6 species, is that chemically prepared supported metal particles are not entirely ligand-free, but contain attached light atoms.
Hydrogen activation by supported Mn species: Supported metal clusters (Fe, Co, Ni, Cu, Ru, Rh, Pd, Ag, Os, Ir, Pt, Au) were found to induce reverse spillover from hydroxylated supports. Especially active are Os and Ir, with nearly 250 kJ/mol gain per transferred hydrogen from an OH group.
Selected Publications
G. N. Vayssilov, B. C.Gates, N. Rösch: Oxidation of supported rhodium clusters by support hydroxy groups, Angew. Chem. Int. Ed. 2003, 42, 1391-1394
G. P. Petrova, G. N. Vayssilov, N. Rösch: Density functional study of hydrogen adsorption on tetrairidium supported on hydroxylated and dehydroxylated zeolite surfaces, J. Phys. Chem. C 2007, 111, 14484-14492
I. V. Yudanov, A. V. Matveev, K. M. Neyman, N. Rösch: How the C-O Bond Breaks During Methanol Decomposition on Nanocrystallites of Palladium Catalysts, J. Am. Chem. Soc. 2008, 130, 9342-9352
I. V. Yudanov, M. Metzner, A. Genest, N. Rösch: Size-Dependence of Adsorption Properties of Metal Nanoparticles: A Density Functional Study on Pd Nanoclusters, J. Phys. Chem. C 2009, 112, 20269–20275
L. V. Moskaleva, Z.-X. Chen, H. H. Aleksandrov, A. Basha Mohammed, Q. Sun, N. Rösch: Ethylene Conversion to Ethylidyne over the Pd(111) Surface: Revisiting the Mechanism with First-Principles Calculations, <cite>J. Phys. Chem. C </cite>2009, 113, 2512–2520
