Synchrotron Spectroscopy

• Development of XAS cells for electrocatalytic materials and photoelectrocatalytic materials. Our cell has been used with epitaxial thin films, electrodeposited thin films and ink-casted thin films
• Operando measurements enabled by an optical oxygen sensor and in situ measurements for other products
• Dedicated workspace to prepare operando/in situ investigations in our laboratory
• Many fruitful collaborations within the materials and electrocatalysis communities

Example publications
J. Du, J. Morales-Santelices, O.Y. Bisen, D. Antipin, D.M. Morales, M. Risch “In situ UV–Vis absorption spectroscopy study of the water electrooxidation on cobalt oxide catalysts”, Electrochim. Acta (2025), doi: 10.1016/j.electacta.2024.145489

Y. Ou, L. Twight, B. Samanta, L. Liu, S. Biswas, J. Fehrs, N. Sagui, J. Villalobos, J. Morales-Santelices, D. Antipin, M. Risch, M. Caspary Toroker, S. Boettcher (2023) “Cooperative Fe Sites on Transition Metal (Oxy) hydroxides for High Oxygen Evolution Activity”, Nat. Commun. (2023), doi: 10.1038/s41467-023-43305-z

M. Risch, D.M. Morales, J. Villalobos, D. Antipin, „What X‐ray absorption spectroscopy can tell us about the active state of earth‐abundant electrocatalysts for the oxygen evolution reaction“, Angew. Chem., Int. Ed.  (2022), doi: 10.1002/anie.202211949

• Simulation and fitting of experimental spectra to determine interatomic distances, number of scattering atoms at a given distance, e.g., coordination number, and disorder to develop structural models even without long range order and crystallinity
• Calculation of parameter errors and goodness of fit parameters to judge reliability of results
• Calculation of parameter error plots for comprehensive insight into parameter correlations and their visualization
• Many fruitful collaborations within the materials and electrocatalysis communities

Example publications
T.G. Yun, B. Chen, S. Wells, Y. Lim, J.S. Kim, A.G. Buzanich, M. Radtke, M.M. Waegele, M. Risch, A. Grimaud „Extrinsic and Intrinsic Factors Governing the Electrochemical Oxidation of Propylene in Aqueous Solutions“, J. Am. Chem. Soc.  (2025), doi: 10.1021/jacs.5c02585 

D.H. Taffa, E. Brim, K.K. Rücker, D. Hayes, J. Lorenz, O. Bisen, M. Risch, C. Harms, R.M. Richards, and M. Wark „Influence of Annealing Temperature on the OER Activity of NiO(111) Nanosheets Prepared via Microwave and Solvothermal Synthesis Approaches“, ACS Appl. Mater. Int. (2024), doi: 10.1021/acsami.4c14277

A. Füngerlings, M. Wohlgemuth, D. Antipin, E. van der Minne, E. Marijn Kiens, J. Villalobos, M. Risch, F. Gunkel, R. Pentcheva, Ch. Baeumer „Crystal-facet-dependent surface transformation dictates the oxygen evolution reaction activity in lanthanum nickelate“, Nat. Commun. (2023), doi: 10.1038/s41467-023-43901-z

J. Villalobos et al., “Requirements for Beneficial Electrochemical Restructuring: A Model Study on a Cobalt Oxide in Selected Electrolytes”, Adv. Energy Mater. (2021), doi: 10.1002/aenm.202101737

• Database of reference spectra
• Protocol for reliable determination of oxidation states

Example publications
J. Villalobos et al., “Requirements for Beneficial Electrochemical Restructuring: A Model Study on a Cobalt Oxide in Selected Electrolytes”, Adv. Energy Mater. (2021), doi: 10.1002/aenm.202101737