Oxygen electrodes are playing a key role in electrochemical energy conversion devices such as fuel cells and water electrolyzers. In both acidic and alkaline environment, both the oxygen reduction and oxygen evolution reaction (ORR and OER), respectively, are limiting the overall energy/voltage efficiency due to its sluggish kinetics. [1, 2]

Whereas in acidic environment, mainly precious metal oxides are used to catalyze the OER (e.g., IrO₂), the variety of possible catalysts in alkaline electrolyte is significantly increased and many metal oxide based systems can be employed. Generally the oxygen evolution mechanism is only partly understood independent of the electrolyte environment and material used. In order to help to understand the underlying mechanism for the OER and to support the experimental results, very often computational methods are used, mainly using density functional theory (DFT) calculations. Similar approaches are also used for gaining insights into catalyst stabilities under operational conditions.

In this talk, some of your recent findings on non-noble metal catalysts, mainly from the perovskite family will be presented. By employing operando X-ray absorption spectroscopy (both XANES and EXAFS), important insights could be gained with respect to the perovskite electronic structure and the local catalyst structure helping to better understand the underlying mechanism for the OER.

Acknowledgement:

This work is supported by the Swiss National Science Foundation, the Swiss Competence Center for Energy Research (SCCER) Heat & Electricity Storage, the Swiss Federal Office of Energy and the Competence Center Energy & Mobility Switzerland.

 References

[1] A. Rabis, P. Rodriguez, T.J. Schmidt, ACS Catal., 2012, 2 (5), 864–890

[2] E. Fabbri, A. Habereder, K. Waltar, R. Kötz, T.J. Schmidt, Cat. Sci. Tech., 2014, 4, 3800-3821