New instrument at BESSY II: The OÆSE endstation in EMIL
The new end station was set up in the EMIL laboratory. © R. Garcia-Diez /HZB
Scheme of the endstation, including the sample environment, the analysis chamber and the operando beamline section. © HZB
A new instrument is now available at BESSY II for investigating catalyst materials, battery electrodes and other energy devices under operating conditions: the Operando Absorption and Emission Spectroscopy on EMIL (OÆSE) endstation in the Energy Materials In-situ Laboratory Berlin (EMIL). A team led by Raul Garcia-Diez and Marcus Bär showcases the instrument’s capabilities via a proof-of-concept study on electrodeposited copper.
Solar cells, catalysts, and batteries are composed of so-called energy materials, i.e., materials that either convert or store energy. Their functionality is based on complex chemical or physical processes. In order to improve their functionality, it is crucially required to understand those processes, ideally while they are taking place, i.e. by in situ and operando studies. A new experimental station enabling corresponding experiments is now available at the Energy Materials In-situ Laboratory Berlin (EMIL) located at the synchrotron facility BESSY II.
The “Operando Absorption and Emission Spectroscopy on EMIL” (OÆSE) provides detailed insights into the electronic and chemical structures of materials and interfaces and their changes during critical (electro)chemical processes via X-ray absorption (XAS) and emission (XES) spectroscopy .
At the heart of the OÆSE endstation is a modular and flexible in situ/operando sample environment, specially tailored to tackle the specific research questions required for each energy material, which design ensures easy adaptation to different experiments.
To demonstrate the capabilities of the OÆSE endstation, the team led by Raul Garcia-Diez and Marcus Bär studied in situ the electrochemical deposition of copper from an aqueous CuSO4 electrolyte using combined soft and hard X-ray absorption spectroscopy exploiting the two-color beamline of EMIL. The case study shows that the new endstation offers valuable insights into dynamic electrochemical processes and thus enables a better understanding of complex electrochemical systems.
- Key technology for a future without fossil fuelsIn June and July 2025, catalyst researcher Nico Fischer spent some time at HZB. It was his sabbatical, he was relieved of his duties as Director of the Catalysis Institute in Cape Town for several months and was able to focus on research only. His institute is collaborating with HZB on two projects that aim to develop environmentally friendly alternatives using innovative catalyst technologies. The questions were asked by Antonia Rötger, HZB.
- Iridium-free catalysts for acid water electrolysis investigatedHydrogen will play an important role, both as a fuel and as a raw material for industry. However, in order to produce relevant quantities of hydrogen, water electrolysis must become feasible on a multi-gigawatt scale. One bottleneck is the catalysts required, with iridium in particular being an extremely rare element. An international collaboration has therefore investigated iridium-free catalysts for acidic water electrolysis based on the element cobalt. Through investigations with various methods, among them experiments at the LiXEdrom at the BESSY II X-ray source in Berlin, they were able to elucidate processes that take place during water electrolysis in a cobalt-iron-lead oxide material as the anode. The study is published in Nature Energy.
- MXene as a frame for 2D water films shows new propertiesAn international team led by Dr. Tristan Petit and Prof. Yury Gogotsi has investigated MXene with confined water and ions at BESSY II. In the MXene samples, a transition between localised ice clusters to quasi-two-dimensional water films was identified by increasing temperature. The team also discovered that the intercalated water structure drives a reversible transition from metallic to semiconducting behaviour of the MXene film. This could enable the development of novel devices or sensors based on MXenes.