Department of
Inorganic Chemistry


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Electronic Structure:
Axel Knop-Gericke
 
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BESSY laboratory
 
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Within the last years we have studied the ethylene/propylene oxidation over silver. The application of in-situ X-ray photoelectron spectroscopy revealed the role of impurities in this reaction. Sulfur forms SO4,ads species on the Ag surface under oxidizing conditions. A positive correlation of the abundance of this species and the yield of the selective oxidation was observed.

Another research topic was the investigation of the oxygen evolution reaction (OER) over different electrodes. The realization of in situ XPS measurements required the development of dedicated reaction cells. This reaction cells were applied to study Ir, Au, Pt and Ru oxide in the OER. For Au oxide, which is strongly covalent, only Au3+ is found, whereas the more oxophyllic Pt displays a gradual transition from Pt0 to Ptd+/Pt2+/Pt4+ and further to Pt4+. For the yet more oxophyllic RuOx, we find a gradual oxidation to primarily Ru4+ under OER conditions, with some minor contributions of higher oxidation states.

The carbon dioxide reduction reaction (CO2RR) over copper was investigated by X-ray spectroscopy in the soft X-ray range as well. By tracking the electronic structure of the Cu catalysts, using X-ray spectroscopies, we were able to tune and precisely set the initial Cu redox state, such as Cu0, Cu+ and Cu2+, by controlled applied potential protocols.

Please find detailed information of the following projects:


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

(to see full size, click on the image)
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
Read more about this project  ... ››
 
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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MoS2 growth by ion implantation and subsequent heating
R. Blume, T. Jones, W. Jang and A. Knop-Gericke
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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
Read more about this project  ... ››
 
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
Read more about this project  ... ››
 
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Address: Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany    
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Tel: +49 30 8413 4404, Fax: +49 30 8413 4401, E-Mail: acsek@fhi-berlin.mpg.de