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.

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
Dr. Andrea Martini
Martina Rüscher

Recent Publications

F. Haase, A. Bergmann, T. Jones, J. Timoshenko, A. Herzog, H. Jeon, C. Rettenmaier and B. Roldan Cuenya: Size effects and active state formation of cobalt oxide nanoparticles during the oxygen evolution reaction. Nature Energy 7 (8), 765–773 (2022).
F. Haase, A. Rabe, F. Schmidt, A. Herzog, H. Jeon, W. Frandsen, P.V. Narangoda , I. Spanos, K.F. Ortega, J. Timoshenko, T. Lunkenbein, M. Behrens, A. Bergmann, R. Schlögl and B. Roldan Cuenya: Role of Nanoscale Inhomogeneities in Co2FeO4 Catalysts during the Oxygen Evolution Reaction. Journal of the American Chemical Society 144 (27), 12007–12019 (2022).
U. Hejral, J. Timoshenko, D. Kordus, M. Lopez-Luna, N.J. Divins, S. Widrinna, I. Zegkinoglou, L. Pielsticker, H. Mistry, J.A. Boscoboinik, S. Kühl and B. Roldan Cuenya: Tracking the phase changes in micelle-based NiGa nanocatalysts for methanol synthesis under activation and working conditions. Journal of Catalysis 405, 183–198 (2022).
C. Li, W. Ju, S. Vijay, J. Timoshenko, K. Mou, D.A. Cullen, J. Yang, X. Wang, P. Pachfule, S. Brückner, H. Jeon, F. Haase, S.-C. Tsang, C. Rettenmaier, K. Chan, B. Roldan Cuenya, A. Thomas and P. Strasser: Covalent Organic Framework (COF) derived Ni-N-C Catalysts for Electrochemical CO2 Reduction: Unraveling Fundamental Kinetic and Structural Parameters of the Active Sites. Angewandte Chemie International Edition 61 (15), e202114707 (2022).
H. Liu, X. Lang, C. Zhu, J. Timoshenko, M. Rüscher, L. Bai, N. Guijarro, H. Yin, Y. Peng, J. Li, Z. Liu, W. Wang, B. Roldan Cuenya and J. Luo: Efficient Electrochemical Nitrate Reduction to Ammonia with Copper supported Rhodium Cluster and Single-Atom Catalysts. Angewandte Chemie International Edition 61 (23), e202202556 (2022).
M. Rüscher, A. Herzog, J. Timoshenko, H. Jeon, W. Frandsen, S. Kühl and B. Roldan Cuenya: Tracking heterogeneous structural motifs and the redox behaviour of copper-zinc nanocatalysts for the electrocatalytic CO2 reduction using operando time resolved spectroscopy and machine learning. Catalysis Science & Technology 12 (9), 3028–3043 (2022).
J. Timoshenko: Spectroscopy predicts catalyst functionality. Nature Catalysis 5 (6), 469–470 (2022).
J. Timoshenko, A. Bergmann, C. Rettenmaier, A. Herzog, R. Aran Ais, H. Jeon, F. Haase, U. Hejral, P. Grosse, S. Kühl, E. Davis, J. Tian, O. Magnussen and B. Roldan Cuenya: Steering the structure and selectivity of CO2 electroreduction catalysts by potential pulses. Nature Catalysis 5 (4), 259–267 (2022).
E. Zschech, E. Topal, K. Kutukova, J. Gluch, M. Löffler, S. Werner, P. Guttmann, G. Schneider, Z. Liao and J. Timoshenko: Multi-scale microscopy study of 3D morphology and structure of MoNi4/MoO2@Ni electrocatalytic systems for fast water dissociation. Micron 158, 103262 (2022).
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).
X. Feng, H. Jena, C. Krishnaraj, D. Arenas-Esteban, K. Leus, G. Wang, J. Sun, M. Rüscher, J. Timoshenko, B. Roldan Cuenya, S. Bals and P. Van Der Voort: Creation of Exclusive Artificial Cluster Defects by Selective Metal Removal in the (Zn, Zr) Mixed-metal UiO-66. Journal of the American Chemical Society 143 (51), 21511–21518 (2021).
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).
H. Jeon, J. Timoshenko, C. Rettenmaier, A. Herzog, A. Yoon, S.W. Chee, S. Oener, U. Hejral, F. Haase and B. Roldan Cuenya: Selectivity control of Cu nanocrystals in a gas-fed flow cell through CO2 pulsed electroreduction. Journal of the American Chemical Society 143 (19), 7578–7587 (2021).
M. Lopez-Luna, J. Timoshenko, D. Kordus, C. Rettenmaier, S.W. Chee, A.S. Hoffman, S.R. Bare, S.K. Shaikhutdinov and B. Roldan Cuenya: Role of the Oxide Support on the Structural and Chemical Evolution of Fe Catalysts during the Hydrogenation of CO2. ACS Catalysis 11 (10), 6175–6185 (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).
S. Saddeler, G. Bendt, S. Salamon, F. Haase, J. Landers , J. Timoshenko, C. Rettenmaier, H. Jeon, A. Bergmann, H. Wende, B. Roldan Cuenya and S. Schulz: Influence of the cobalt content in cobalt iron oxides on the electrocatalytic OER activity. Journal of Materials Chemistry A 9 (45), 25381–25390 (2021).
J. Timoshenko and B. Roldan Cuenya: In Situ/Operando Electrocatalyst Characterization by X-ray Absorption Spectroscopy. Chemical Reviews 121 (2), 882–961 (2021).
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).
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).
H.N. Nong, L. Falling, A. Bergmann, M. Klingenhof, H.P. Tran, C. Spöri, R. Mom, J. Timoshenko, G. Zichittella, A. Knop-Gericke, S. Piccinin, 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 (7834), 408–413 (2020).
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).
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).
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).
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).
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).
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).


Timoshenko, J.: Tracking Dynamics and Heterogeneity in Working Nanocatalysts Using Time Resolved Synchrotron Studies and Machine Learning. FHI-Workshop on Current Research at the Interface of Physics and Chemistry, Potsdam, Germany (2022)
Timoshenko, J.: In-Situ/Operando X-ray Absorption Spectroscopy. HZB Photon School 2022, Berlin, Germany (2022)
Timoshenko, J.: Basic and Advanced Analysis of Extended X-ray Absorption Fine Structure. HZB Photon School 2022, Berlin, Germany (2022)
Timoshenko, J.: Probing Disorder in Nanoparticles Using In-Situ X-ray Absorption Spectroscopy and Machine Learning. E-MRS Spring Meeting 2021, Online Event (2021)
Timoshenko, J.: Probing Kinetics of Catalyst Transformations Using Synchrotron-Based Operando Techniques and Machine Learning. 6th International School-Conference on Catalysis for Young Scientists, Catalyst Design: From Molecular to Industrial Level, Online Event (2021)
Timoshenko, J.: Tracking the Structure and Composition of Copper-Based Catalysts for CO2 Electroreduction Using Operando XAS. ACS Spring Meeting 2021, Online Event (2021)
Timoshenko, J.: Machine Learning Algorithms for the Analysis of Spectroscopy Data. DGM Training Course, Correlative Materials Characterization, Online Event (2021)
Timoshenko, J.: In Situ/Operando Electrocatalyst Characterization by X-Ray Absorption Spectroscopy. Chemical Reviews Virtual Lecture Series, Online Event (2021)
Timoshenko, J.: In Situ/Operando X-Ray Absorption Spectroscopy. HZB Photon School 2021, Online Event (2021)
Timoshenko, J.: Basic and Advanced Analysis of Extended X-Ray Absorption Fine Structure. HZB Photon School 2021, Online Event (2021)
Timoshenko, J.: Reverse Monte Carlo Modelling and Neural Networks in EXAFS Analysis. Advanced XAS Data Analysis and Modeling Virtual Workshop 2020, Online Event (2020)
Timoshenko, J.: In-Situ/Operando X-ray Absorption Spectroscopy. HZB Photon School 2020, Berlin, Germany (2020)
Timoshenko, J.: Electrochemical Reduction and Brass Formation in Copper-Zinc Nanocatalysts: Deciphering In-Situ EXAFS Data Using Artificial Neural-Network. E-MRS Fall Meeting and Exhibit 2019, Warsaw, Poland (2019)
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