Advanced spectroscopy of electrode-electrolyte interface during oxygen evolution reaction (OER)

Water electrolyzers play a central role in the implementation of renewable energy storage in the form of chemical bonds. These electrolyzers rely on catalysts at the anode and cathode sides to carry on the redox reactions and understanding the nature of active sites of the catalysts is the key to controlling the electrocatalytic activity. The oxygen evolution reaction (OER) occurring at the anode side of a water electrolyzer is the limiting reaction because it is very sluggish and requires large overpotential due to the involvement of four electron transfer in a multistep reaction process. The project is focused on the investigation of the effect of cations, anions, and pH of the electrolyte on the activity, dissolution rate, and operando structure of amorphous and rutile 𝐼𝑟𝑂x and 𝑅𝑢𝑂x electrocatalysts during the OER. To this end, we will use synchrotron-based operando X-ray absorption spectroscopy (XAS), near ambient pressure XPS (NAP-XPS), and plasmon-enhanced raman spectroscopy. With these advanced spectroscopic techniques, we intend to probe the adsorbates, deprotonation, and oxidation events at the electrode-electrolyte interface during OER as well as the hydrogen bonding in the near surface electrolyte in order to elucidate the interfacial water structure at OER relevant potentials and its influence on the reaction mechanism, activity and stability of the catalyst.

The group of Dr. Axel Knop-Gericke at FHI Berlin has more than a decade long experience in the field of synchrotron-based operando XAS, and NAP-XPS which are vital tools for the study of electrocatalysts during in-situ conditions. These advanced x-ray spectroscopy techniques can provide an atomic level understanding of the behavior of active sites during OER which would enable design of efficient catalysts for future. The research group of Dr. Ralph Krähnert at TU Berlin has an expertise in the synthesis and characterization of mesoporous 𝐼𝑟𝑂x and 𝑅𝑢𝑂x electrocatalysts. These materials due to its large surface area are excellent candidates for studying the physical origin of the nature of active sites during OER and its influence on the reaction mechanism, and activity.