Electrochemical splitting of H₂O and CO₂ will play a key role for future energy supply based on renewables. Since most renewable energy sources such as solar or wind are intermittent, it is necessary to transformation the generated energy into a persistent form, which can be used on demand. This and more can be done via electrolysis. The provision of renewably produced H₂ and CO offers the opportunity of producing sustainable hydrocarbon fuels, which have a couple of advantages over hydrogen such as high volumetric energy density, safe and easy storability, and compatibility with existing fuel infrastructure. To achieve the required energy system transformation, highly active and long-term stable electrode materials for electrolysis of H₂O and CO₂ are needed.

In our research, we focus on mixed ionic and electronic conducting (MIEC) materials for high temperature H₂O and CO₂ splitting in solid oxide electrolysis cells. On these materials, the surface composition and bulk defect chemistry and their importance for the electro-catalytic activity of the electrode are extremely interesting. To unravel the role of different factors influencing the activity of such materials, we often combine electrochemical techniques such as impedance spectroscopy or d.c. measurements with analytical methods – often also in-situ. This combination allows deep insights into the complex reaction mechanisms on the surfaces of the electrodes. For example, the role of surface-decorating particles – which can be highly beneficial but also very detrimental – is currently an intensely investigated topic.