Comprehensive and fundamental understanding of the physical and chemical processes during electrochemical energy conversion is critical to optimize electrochemical devices. Therefore, the fundamental research has to be coordinated with the applied research and technologically realization. Our key reactions comprise the electrochemical conversion of greenhouse gases and environmentally pollutant molecules to store energy from renewable power sources and to produce feedstock chemicals and fuels.
In particular, we aim to identify key properties to efficiently produce hydrocarbons, like ethylene, and alcohols, like ethanol, from CO2 as well as H2 and ammonia from water and nitrate in CO2RR, OER, and NO3RR. All these reactions comprise bond-breaking and ‑making steps which we aim to understand on electrocatalytically-relevant time scales.
Our approach comprises well-defined model catalysts in which key properties of realistic catalysts (supported nanoparticles or catalysts coatings) can be tailored and studied separately. We utilize, for example, size- and shape-selected nanoparticles of metals and metal oxides as well as thin films. We focus on the catalysts systems based on relevant, abundant, inexpensive 3d transition metals such as Co, Fe, Ni, Cu, and Zn but also IrOx for acidic OER.
In addition to the comprehensive characterization of the pre- and post-catalytic states using the broad range of methodologies available at the Department of Interface Science, we achieve operando insights on the adaptations of the (bulk) structure, the near-surface chemistry, the ensemble of surface adsorbates as well as the electrolyte state primarily via operando electrochemical (grazing incidence and high-energy) X-ray diffraction, surface-enhanced Raman and X-ray photoemission spectroscopy (s. figure above). Therefore, we utilize lab-based experimental setups and conduct experiments at synchrotron facilities. Furthermore, we strongly collaborate with the Research Groups of Liquid Electron Microscopy (S.W. Chee) and Advanced X-ray Spectroscopy (J. Timoshenko) to better understand the (reversible) changes of the nanocatalysts morphology as well as local atomic structure under electrocatalytic conditions.
G. Wartner, D. Hein, A. Bergmann, R. Wendt, B. Roldan Cuenya and R. Seidel: Insights into the electronic structure of Fe-Ni thin-film catalysts during oxygen evolution reaction using operando resonant Photoelectron Spectroscopy. Journal of Materials Chemistry A11 (15), 8066–8080 (2023).
N. Daems, D. Choukroun, P. Merino, C. Rettenmaier, L. Pacquets, A. Bergmann, G. Santoro, L. Vázquez, L. Martínez, B. Roldan Cuenya, J.A. Martín Gago and T. Breugelmans: Steering Hydrocarbon Selectivity in CO2 Electroreduction over Soft-Landed CuOx Nanoparticle-Functionalized Gas Diffusion Electrodes. ACS Applied Materials and Interfaces14 (2), 2691–2702 (2022).
C. Zhan, F. Dattila, C. Rettenmaier, A. Bergmann, S. Kühl, R. García-Muelas, N. Lopez and B. Roldan Cuenya: Revealing the CO Coverage Driven C-C Coupling Mechanism for Electrochemical CO2 Reduction on Cu2O Nanocubes via Operando Raman Spectroscopy. ACS Catalysis11 (13), 7694–7701 (2021).
F. Dionigi, Z. Zeng, I. Sinev, T. Merzdorf, S. Deshpande, M.B. Lopez, S. Kunze, I. Zegkinoglou, H. Sarodnik, D. Fan, A. Bergmann, J. Drnec, J.F.D. Araujo, M. Gilech, D. Teschner, J. Zhu, W. Li, J.P. Greeley, B. Roldan Cuenya and P. Strasser: In-situ structure and catalytic mechanism of NiFe and CoFe layered double hydroxides during oxygen evolution. Nature Communications11, 2522 (2020).
M. Bernal, A. Bagger, F. Scholten, I. Sinev, A. Bergmann, M. Ahmadi, J. Rossmeisl and B. Roldan Cuenya: CO2 electroreduction on copper-cobalt nanoparticles: Size and composition effect. Nano Energy53, 27–36 (2018).
K. Klingan, T. Kottakkat, Z.P. Jovanov, S. Jiang, C. Pasquini, F. Scholten, P. Kubella, A. Bergmann, B. Roldan Cuenya, C. Rot and H. Dau: Reactivity Determinants in Electrodeposited Cu Foams for Electrochemical CO2 Reduction. ChemSusChem11 (19), 3449–3459 (2018).
Bergmann, A.: Understanding Redox Electrochemistry and Active State Formation of Electrocatalysts: Operando Insights Into Size Effects and Dynamics. FHI-Workshop on Current Research Topics at the FHI, Online Event (2021)
Bergmann, A.: In situ Studies to Understand (Electro)chemical Energy Conversion–XAFS and XRD on Nanocatalysts during Alcohol Oxidation and Oxygen Evolution. 13th EERA AMPEA Joint Programme Steering Committee and AMPEA-EERA workshop: Synchrotron Radiation and Neutron Scattering for Energy Materials, Berlin, Germany (2018)