Proton Transport in the Gadolinium-Doped Layered Perovskite BaLaInO4

Layered Perovskites BaLnnInnO3n+1 (n = 1, 2) for Electrochemical Applications: A Mini Review

Modern humanity is facing many challenges, such as declining reserves of fossil energy resources and their increasing prices, climate change and an increase in the number of respiratory diseases including COVID-19. This causes an urgent need to create advanced energy materials and technologies to support the sustainable development of renewable energy systems including hydrogen energy. Layered perovskites have many attractions due to their physical and chemical properties. The structure of such compounds contains perovskite layers divided by layers with different frameworks, which provide their properties' features. Proton-conduction layered perovskites open up a novel structural class of protonic conductors, potentially suitable for application in such hydrogen energy devices as protonic ceramic electrolysis cells and protonic ceramic fuel cells. In this mini review, the special features of proton transport in the novel class of proton conductors BaLn_nIn_nO_3n+1 (n = 1, 2) with a layered perovskite structure are observed and general regularities are discussed.

Novel Protonic Conductor SrLa2Sc2O7 with Layered Structure for Electrochemical Devices

Novel materials with target properties for different electrochemical energy conversion and storage devices are currently being actively created and investigated. Materials with high level of protonic conductivity are attracting attention as electrolytes for solid oxide fuel cells and electrolyzers. Though many materials are being investigated as potential electrolytic components for these devices, many problems exist, including comparability between electrodes and electrolytes. In this paper, layered perovskite SrLa₂Sc₂O₇ was investigated as a protonic conductor for the first time. The possibility for water uptake and protonic transport was revealed. It was shown that the SrLa₂Sc₂O₇ composition can be considered a prospective ionic conductor. The layered perovskites can be considered as very promising materials for electrochemical devices for energy applications.

Synthesis, Hydration Processes and Ionic Conductivity of Novel Gadolinium-Doped Ceramic Materials Based on Layered Perovskite BaLa2In2O7 for Electrochemical Purposes

The search for novel highly effective materials with target properties for different electrochemical purposes is active for now. Ceramic materials with high levels of ionic conductivity can be applied as electrolytic materials in solid oxide fuel cells and in electrolyzers. Layered perovskites are a novel class of ionic conductors demonstrating almost-pure proton transportation at mid-temperatures. Gadolinium-doped ceramic materials based on layered perovskite BaLa2In2O7 were obtained and investigated for the first time in this study. The effect of the dopant concentrations on the hydration processes and on ionic conductivity was revealed. It was shown that compositions 0 ≤ x ≤ 0.15 of BaLa2–xGdxIn2O7 exhibited proton conductivity when under wet air and at mid-temperatures (lower than ~450 °C). Gadolinium doping led to an increase in the conductivity values up to an order of magnitude of ~0.5. The protonic conductivity of the most conductive composition BaLa1.85Gd0.15In2O7 was 2.7∙10−6 S/cm at 400 °C under wet air. The rare earth doping of layered perovskites is a prospective approach for the design of ceramics for electrochemical devices for energy applications.