Modernized Synthesis Technique of Pr2NiO4+δ-Based Complex Oxides Using Low-Temperature Salt Melts.

Phases based on layered lanthanide nickelates are considered as promising electrode materials for various electrochemical devices, including solid oxide fuel cells and electrolysis cells. While such compounds may be prepared using either solid state or solution-assisted syntheses, each of these approaches entails certain problems. In the present work, we propose a novel approach for the simple and straightforward preparation of Pr2NiO4+δ-based materials. This approach involves co-melting of initial nitrate components, followed by high-temperature decomposition of the obtained mixture. The developed synthesis method exhibits a number of advantages over conventional techniques, enabling highly dispersed and single-phase powders to be obtained at a reduced synthesis temperature of 1050 °C. Therefore, the results of this work open new possibilities for the cost-effective preparation of Ruddlesden-Popper oxide phases.

Nickel-Containing Perovskites, PrNi0.4Fe0.6O3-δ and PrNi0.4Co0.6O3-δ, as Potential Electrodes for Protonic Ceramic Electrochemical Cells.

Protonic ceramic fuel cells (PCFCs) offer a convenient means of converting chemical energy into electricity with high performance and efficiency at low- and intermediate-temperature ranges. However, in order to ensure good life-time stability of PCFCs, it is necessary to ensure rational chemical design in functional materials. Within the present work, we propose new Ni-based perovskite phases of PrNi0.4M0.6O3-δ (where M = Co, Fe) for potential utilization in protonic ceramic electrochemical cells. Along with their successful synthesis, functional properties of the PrNi0.4M0.6O3-δ materials, such as chemical compatibility with a number of oxygen-ionic and proton-conducting electrolytes, thermal expansion behavior, electrical conductivity, and electrochemical behavior, were comprehensively studied. According to the obtained data, the Co-containing nickelate exhibits excellent conductivity and polarization behavior; on the other hand, it demonstrates a high reactivity with all studied electrolytes along with elevated thermal expansion coefficients. Conversely, while the iron-based nickelate had superior chemical and thermal compatibility, its transport characteristics were 2-5 times worse. Although, PrNi0.4Co0.6O3-δ and PrNi0.4Fe0.6O3-δ represent some disadvantages, this work provides a promising pathway for further improvement of Ni-based perovskite electrodes.