Research

Electronic structure group

The electronic structure of catalytically active solid materials constitutes the focus of our research. Surface reactions and elementary steps are strongly influenced by the local electronic and geometric properties of the surface. We deal with heterogenous as well as electrocatalysts and therefore we investigate both solid-gas and solid-liquid interfaces.

Electro-chemical cell for investigations of the electronic structure of solid-liquid interfaces relevant for electro-chemical processes.

Our model of heterogeneous catalysis evolved in the last 100 years and now we understand that the catalyst itself does not remain completely unchanged under reaction conditions. In fact, the as-synthesized catalyst can be best seen as only a precursor to the active-phase/active-site ensemble, which is created under operational conditions. Mass and energy transport, local chemical potential, and a catalyst's geometric and electronic structure are all strongly interconnected through the catalyst’s dynamics. This creates feedback loops that make it necessary to study catalytic phenomena under reaction conditions. Based on these principles, our core activities are synchrotron based in-situ/operando X-ray absorption (XAS) and X-ray photoelectron spectroscopy (XPS) experiments, often complemented with DFT calculations, to understand structure-function relations governing catalytic performance.

Our solid sample are sometimes model catalysts but we investigate also high-performance catalysts and therefore we rely on the synthesis expertise anchored in the Catalysis with Oxides and Catalysis on Metal groups. The close collaboration with the Electron Microscopy group enables us to link the electronic structure of the catalysts to their geometric and structural properties.

Please find detailed information of the following projects:

By using pulse voltammetry, operando X-ray absorption and photoelectron spectroscopy (XAS, XPS) measurements together with DFT calculations on iridium oxide we show that the applied bias does not act directly on the reaction coordinate, but affects the electrocatalytically generated current through charge accumulation in the catalyst. We find that the logarithm of the rate of OER linearly correlates with the charge accumulated. The applied potential drives the formation of empty Ir 5d states, ascribed to formally Ir5+ species, and the concomitant appearance of electron-deficient oxygen surface species (μ1-O and μ2-O) that are responsible for water activation and oxidation. more

In operando XPS and XAS on oxygen evolution reaction catalysts in confined liquid electrolyte

Rik Mom, Lorenz Frevel, Juan Velasco-Velez, Travis Jones, Detre Teschner, Katarzyna Skorupska, Axel Knop-Gericke, Robert Schlögl
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Differentiation of strongly bound oxygen on silver

F. Sulzmann, E.A. Carbonio, T. Jones, A. Klyushin, A. Knop-Gericke, R. Schlögl
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Cobalt in the OER and Isopropanol Oxidation

T. Götsch, A. Klyushin, T. Lunkenbein, R. Schlögl, A. Knop-Gericke
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Unifying concepts for electrochemical water splitting on various iridium (hydr-) oxides

Lorenz J. Falling, Detre Teschner, Juan-Jesús Velasco-Vélez, Hong Nhan, Rik Mom, Axel Knop-Gericke, Travis E. Jones, Robert Schlögl
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SOx on Ag catalysts and its role in alkene epoxidation

Emilia A. Carbonio, Alexander Yu. Klyushin, Frederic Sultzmann, Michael Hävecker, Simone Piccinin, Axel Knop-Gericke, Travis E. Jones, Robert Schlögl
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CO2 electroreduction on copper catalysts investigated by in situ X-ray spectroscopy

Juan-Jesús Velasco-Vélez, Qingjun Zhu, Cheng-Hao Chuang, Travis Jones, Dunfeng Gao, Emilia Carbonio, Beatriz Roldan Cuenya, Robert Schlögl, Axel Knop-Gericke
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New facilities BElChem and CAT@EMIL dedicated to ambient pressure X-ray electron spectroscopy put into operation at HZB/BESSY

M. Hävecker, E. Stotz, M. Gorgoi, St. Hendel, A. Knop-Gericke, R. Schlögl
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