Natalia Tarasova notes that the new material is harmless to the environment. Credit: Ilya Safarov |
Scientists at Ural Federal University and the Institute of High Temperature Electrochemistry, Ural Branch of the Russian Academy of Sciences have synthesized a proton conductor, a solid electrolyte in which positively charged hydrogen (proton) particles are current carriers. It has a high level of electrical conductivity and could become the basis for a solid oxide fuel cell (SOFC). Such cells are an environmentally friendly alternative to hydrocarbon energy sources. The results of the study are published in the International Journal of Hydrogen Energy, an international journal dedicated to hydrogen energy.
Solid oxide fuel cells are instruments that convert fuel energy into electrical energy through a chemical reaction. SOFC is used in hydrogen power, they can replace fossil fuel sources and reduce their impact on climate change and air pollution. Such cells can be used in car engines or the space industry to reduce hydrocarbon emissions into the environment. Fuel cells based on the new material developed by scientists are potentially cost-effective to produce and can exhibit higher electrical conductivity than other solid-state conductors for SOFC.
"The transition to clean hydrogen energy is one of the possible ways to solve the problem of fossil fuel pollution. Proton-ceramic fuel cells are a promising alternative to hydrocarbon engines, because they combine high efficiency, flexibility in various operating conditions, and excellent performance. In our work we obtained a new energy-efficient material in which the proton concentration is doubled and the electrical conductivity becomes two times higher. It is important to note that the material shows such results at a temperature that is twice as low as the currently most studied solid-state oxygen-ion conductors. Lowering the temperature increases the economic efficiency of the final electrochemical device," explains the study's co-author Natalia Tarasova, Associate Professor at the Department of Physical Chemistry at UrFU.
The isovalent doping method made it possible for scientists to obtain the new material. It was first used to improve the properties of the substance under study. It turned out that this method helped to achieve high indicators. Isovalent doping means substitution of atoms of the initial structure with atoms of another chemical element of the same valence. In this case, they used barium-lanthanum indate (a compound of barium, lanthanum, indium, and oxygen), where scientists substituted half of the indium atoms for yttrium.
"Solid-state proton conductors, which can be used in SOFC, introduce protons into themselves from moist air, that is, from the water contained in it. Yttrium has a larger radius than indium, and when introduced, it "pulls apart" the crystal lattice of the source material. This allows the altered lattice to "accumulate" twice as many protons from the humidified atmosphere," adds Natalia Tarasova.
Materials based on barium-lanthanum indate with a block-layer structure are a unique development of Ural scientists. Before their discovery, materials with a perovskite (calcium titanate) structure were mainly studied as proton conductors. The team now selects and tests such a composition of a solid-state proton conductor, which in the future will become the basis for a high-performance and economically affordable proton fuel cell for environmentally friendly and resource-saving energy. Earlier, scientists also found out how the properties of a conductor based on barium-lanthanum indate change when some atoms are replaced with barium and titanium atoms.
The research was carried out with financial support from the Ministry of Science and Higher Education of the Russian Federation (state assignment No. 075-03-2021-051/5). The experimental part was carried out in the Laboratory of Hydrogen Energy of UrFU, which is a part of the Ural Interregional Research and Education Center "Advanced Industrial Technologies and Materials" (UIREC). The laboratory team includes scientists from Ural Federal University and the Institute of High Temperature Electrochemistry, Ural Branch of the Russian Academy of Sciences.
Source/Credit: Ural Federal University
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