Operando Hard X-ray Spectroscopy

Operando Hard X-ray Spectroscopy

Synchrotron radiation facilities are powerful X-ray sources that can be employed for numerous experimental techniques, including X-ray spectroscopic, scattering and imaging methods. The features of synchrotron radiation - high intensity and broad energy spectrum - make these sources ideally suited for in-situ and operando investigations of advanced materials.

Time-resolved operando X-ray absorption spectroscopy data are deciphered using machine learning methods to extract fingerprints of evolving structural motifs.

In the focus of our group's research is the application and development of complementary synchrotron radiation techniques (X-ray absorption spectroscopy, high-energy X-ray diffraction coupled with pair distribution function analysis, small-angle X-ray scattering) that provide information about the transformations of catalyst structure on different length and time scales under catalytically relevant conditions.

By combining unique synthesis methods, state-of-the art tools for experimental characterization and advanced approaches to data analysis, atomistic details of chemical and electrochemical reactions at gas/solid and liquid/solid interfaces are revealed, and structure-property relationship in these materials are established.

Group Members

Dr. Janis Timoshenko
Dr. Uta Hejral

Recent Publications

A. Herzog, A. Bergmann, H. Jeon, J. Timoshenko, S. Kühl, C. Rettenmaier, M. Lopez-Luna, F. Haase and B. Roldan Cuenya: Operando Investigation of Ag‐Decorated Cu2O Nanocube Catalysts with Enhanced CO2 Electroreduction toward Liquid Products. Angewandte Chemie International Edition 60 (13), 7426–7435 (2021).
N.J. Divins, D. Kordus, J. Timoshenko, I. Sinev, I. Zegkinoglou, A. Bergmann, S.W. Chee, S. Widrinna, O. Karslıoğlu, H. Mistry, M. Lopez Luna, J.Q. Zhong, A.S. Hoffmann, A. Boubnov, J.A. Boscoboinik, M. Heggen, R.E. Dunin-Borkowski, S.R. Bare and B. Roldan Cuenya: Operando high-pressure investigation of size-controlled CuZn catalysts for the methanol synthesis reaction. Nature Communications 12, 1435 (2021).
J. Timoshenko and B. Roldan Cuenya: In Situ/Operando Electrocatalyst Characterization by X-ray Absorption Spectroscopy. Chemical Reviews 121 (2), 882–961 (2021).
R. Rizo, A. Bergmann, J. Timoshenko, F. Scholten, C. Rettenmaier, H. Jeon, Y.-T. Chen, A. Yoon, A. Bagger, J. Rossmeisl and B. Roldan Cuenya: Pt-Sn-Co nanocubes as highly active catalysts for ethanol electro-oxidation. Journal of Catalysis 393, 247–258 (2021).
C. Rettenmaier, R. Aran Ais, J. Timoshenko, R. Rizo, H. Jeon, S. Kühl, S.W. Chee, A. Bergmann and B. Roldan Cuenya: Enhanced Formic Acid Oxidation over SnO2-decorated Pd Nanocubes. ACS Catalysis 10 (24), 14540–14551 (2020).
S. Kunze, P. Grosse, M.B. Lopez, I. Sinev, I. Zegkinoglou, H. Mistry, J. Timoshenko, M.Y. Hu, J. Zhao, E.E. Alp, S.W. Chee and B. Roldan Cuenya: Operando NRIXS and XAFS Investigation of Segregation Phenomena in Fe‐Cu and Fe‐Ag Nanoparticle Catalysts during CO2 Electroreduction. Angewandte Chemie International Edition 59 (50), 22667–22674 (2020).
H.N. Nong, L. Falling, A. Bergmann, M. Klingenhof, H.P. Tran, C. Spöri, R. Mom, J. Timoshenko, G. Zichittella, A. Knop-Gericke, S. Picicinin, J. Pérez-Ramírez, B. Roldan Cuenya, R. Schlögl, P. Strasser, D. Teschner and T. Jones: Key role of chemistry versus bias in electrocatalytic oxygen evolution. Nature 587, 408–413 (2020).
T. Möller, F. Scholten, T.N. Thanh, I. Sinev, J. Timoshenko, X. Wang, Z. Jovanov, M. Gliech, B. Roldan Cuenya, A.S. Varela and P. Strasser: Electrocatalytic CO2 Reduction on CuOx Nanocubes: Tracking the Evolution of Chemical State, Geometric Structure, and Catalytic Selectivity using Operando Spectroscopy. Angewandte Chemie International Edition 59 (41), 17974–17983 (2020).
J. Timoshenko, H. Jeon, I. Sinev, F. Haase, A. Herzog and B. Roldan Cuenya: Linking the evolution of catalytic properties and structural changes in copper–zinc nanocatalysts using operando EXAFS and neural-networks. Chemical Science 11 (14), 3727–3736 (2020).
H. Jeon, J. Timoshenko, F. Scholten, I. Sinev, A. Herzog, F. Haase and B. Roldan Cuenya: Operando Insight into the Correlation between the Structure and Composition of CuZn Nanoparticles and their Selectivity for the Electrochemical CO2 Reduction. Journal of the American Chemical Society 141 (50), 19879–19887 (2019).
D. Gao, I. Sinev, F. Scholten, R. Aran Ais, N.J. Divins, K. Kvashnina, J. Timoshenko and B. Roldan Cuenya: Selective CO2 Electroreduction to Ethylene and Multicarbon Alcohols via Electrolyte-Driven Nanostructuring. Angewandte Chemie International Edition 58 (47), 17047–17053 (2019).
J. Timoshenko and A.I. Frenkel: “Inverting” X-ray Absorption Spectra of Catalysts by Machine Learning in Search for Activity Descriptors. ACS Catalysis 9 (11), 10192–10211 (2019).
M. Ahmadi, J. Timoshenko, F. Behafarid and B. Roldan Cuenya: Tuning the Structure of Pt Nanoparticles through Support Interactions: An In Situ Polarized X-ray Absorption Study Coupled with Atomistic Simulations. The Journal of Physical Chemistry C 123 (16), 10666–10676 (2019).
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