The ongoing technical development and global industrialization have resulted in a growing demand for fossil fuels. The reduction of carbon dioxide amount and the development of renewable energy sources are the most urgent challenges that governments and the society are facing nowadays. One of the most promising methods to utilize CO₂ from burning fossil fuels, is the conversion of carbon dioxide into valuable chemicals. Affordable production of hydrocarbons can be achieved using e.g., Fischer-Tropsch synthesis utilizing H₂ and CO. Unfortunately, the ecological hydrogen production as well as obtaining pure CO are still problematic. Electrochemical reduction of CO₂ and H₂O is believed to be one of the most promising conversion strategies, that could possibly consume excess energy to efficiently produce value-added chemicals.
The Solid Oxide Electrolysis Cell (SOEC) used in the variety of research devoted to the ‘green’ hydrogen provision possesses two major advantages over other electrolysis techniques (e.g. alkaline electrolysers). Higher operating temperatures of SOECs enhance the kinetics of the water electrolysis process. Furthermore, these are capable of simultaneous reduction of CO₂, if it is delivered to the inlet mixture along with water vapor. Although coelectrolysis of H₂O/CO₂ has been studied for a long time, a clear description of the process is still lacking due to its complex nature. Proper catalysts should be used to increase the efficiency of the coelectrolysis process. An interesting group of catalysts are bimetallic nanoparticles supported on the SOEC’s electrode.
In this study, a series of novel SOECs has been fabricated by βCD-assisted 2-cycle wet impregnation method. The conventional Ni-YSZ bulk cermet electrodes were enriched with 3.6 wt.% of the nanoparticles of the Mn, Co, Fe, Cu, Zn oxide, which upon reduction formed mixed core-shell-like structures on the Ni grains. The obtained structure was deeply characterized using synchrotron radiation in Scanning Transmission X-ray Microscopy (STXM) to reveal the complexity of the bimetallic structures. The chemical imaging studies were accompanied by the measurements using Near-Ambient Pressure X-ray Photoelectron Spectroscopy (NAP-XPS) performed under the flow of reactant mixture at elevated temperatures. The addition of the secondary metal alters the energy levels on the Ni surface and increases the tendency to form carbonates, what prolongs the retention time of CO₂. Finally, the cells with infiltrated electrodes were tested i.a. in the H₂O/CO₂ coelectrolysis mode at 700 ? under thermoneutral voltage of 1.3 V. The addition of guest metal increased the CO2 conversion and selectivity towards CO production due to the existing surficial modifications of e.g. basic-acid sites. Long-term tests revealed lower degradation of the modified cells. This simple approach for modification of the SOEC can lead to better understanding of the correlation between the properties of the fuel electrode material and the overall efficiency of the coelectrolysis process.

Acknowledgements
This work was supported by a project OPUS22 funded by National Science Centre Poland, based on decision UMO-2021/43/B/ST8/01831. We also acknowledge SOLARIS Centre for the access to the Beamline DEMETER. The XAS experiments were performed on beamline BM08 (LISA) at the European Synchrotron Radiation Facility (ESRF), Grenoble, France.