Identification number: lzp-2021/1-0203
Type: Fundamental and applied research project of the Latvian Council of Science
Project duration: 2022 - 2024
Project manager: Dr.rer.nat D. Gryaznov, ISSP UL
Total funding: 300 KEUR
Project summary:
The climate change is unprecedentedly important issue for our planet. One of the approaches to minimize its effect is based on the development of effective green technologies. Solid oxide electrolysis cells (SOECs) are used to convert CO2 into useful, chemically valuable materials and other products by the electrochemical process. Besides, the SOECs can be used in either oxide ion conduction or proton conduction (PCEC) mode. The latter mode is of particular interest as it offers possibilities for the co-electrolysis and intermediate temperature regimes due to higher proton conductivities of electrolyte materials. Presently, the greatest challenge for the SOECs technologies is the performance degradation at high temperatures and cost. The main goal of the proposed theoretical project is prediction of new PCEC anode materials on the basis of mixed ion-electron hole conducting oxides for inter-mediate temperatures (300-600o C). Therefore, we consider Ruddlesden-Popper phases (Sr,La)n+1FenO3n+1 with variation of phase order n as effective anodes materials for the PCECs. The following issues will be uncovered: (i) relations between crystal structure and properties for high proton and p-type electronic conductivity; (ii) proton incorporation mechanisms by acid-base or by redox reaction; (iii) chemical and thermal expansion issues accompanying water incorporation; (iv) development and applications of evolutionary algorithms for accurate defect structures in density functional theory calculations.
ON THE IMPLEMENTATION OF THE PROJECT (PERIOD 2022-2023)
Existence of Jahn-Teller effect is shown and explained in detail in Sr2FeO4 for the first time. It is achieved by very accurate calculations with the state-of-the-art hybrid density functionals combined with a rigorous group theory analysis. Such results help in the interpretations of magnetic strcuture and other experiments and signifincantly improve the relevant estimations of defect formation energies from the DFT calculations in the present material. Published in Scientific Report 13, 16446 (2023).
https://doi.org/10.1038/s41598-023-43381-7
One of the activities within the project is a comparison between the materials representing different alternatives for the relevant applications. So, proton migration has been studied in BaFeO3- using the DFT+U calculations. In this case protons are attached to oxygen to form a strong covalent O-H bond, and are understood as hydroxyl groups on a regular oxygen site. In addition to the calculated migration barriers, important descriptors helping in understanding the proton migration mechanism have been established and carefully analyzed. We, thus, have found correlations of the migraton barrier height with the initial O-O distance and the O-H bond length. Published in Journal of Materials Chemistry A 11, 6336-6348 (2023).
https://doi.org/10.1039/D2TA08664F