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

Abstract

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 BaLnnInnO3n+1 (n = 1, 2) with a layered perovskite structure are observed and general regularities are discussed.

Heterovalent and isovalent doping of bilayer proton-conducting perovskite SrLa2Sc2O7

“…The graphical representation for the samples with nominal compositions SrLa2Sc1.9Gd0.1O7 and SrLa2Sc1.9Ti0.1O7.05 is shown in Figure 3. As previously shown for the bilayer perovskites BaLa2In2O7 and BaNd2In2O7 [42], the donor doping of the indium sublattice is almost non-existent, in contrast to monolayer perovskites. The crystal lattice of bilayer perovskite contains a linkage of two layers of octahedrons in one perovskite layer and is more rigid compared to the monolayer perovskite layered structure where the layers of the perovskite block are one layer of octahedrons.…”

Synthesis and electrical properties of doped layered perovskites based on BaMInO4 (M = Y, Gd)

“…The complex oxides with high temperature protonic conductivity are actively studied due to their potential applications in electrochemical devices such as proton-conducting fuel cells (PCFC) and electrolyzers (PCEC) [1][2][3][4][5][6][7][8]. The design and production of such devices is part of the strategy of sustainable environmental development [9][10][11][12][13][14][15][16]. The most studied proton conductors are barium cerates-zirconates [17][18][19][20][21][22][23][24].…”

Novel co-doped protonic conductors BaLa1.9Sr0.1In1.95M0.05O6.925 with layered perovskite structure

“…Electrochemical devices such as proton-conducting fuel cells [1][2][3] and electrolyzers [4,5] are in dire need of highly efficient materials with targeted properties including proton conductivity [6][7][8]. Active development and implementation of these devices as a part of the "hydrogen energy in everyday life" strategy should ensure sustainable environmental development [9][10][11][12][13][14][15][16]. The electrolyte material of a hydrogen-powered electrochemical device must satisfy a number of requirements, including high proton conductivity.…”

“…The possibility of proton conductivity in bilayer AA′2B2O7 perovskites such as on BaLa2In2O7 [42][43][44], BaNd2In2O7 [45] and SrLa2Sc2O7 [46] and compositions based on them was described last year. It was shown that doping cationic sublattices can improve oxygen-ion and proton conductivity by up to 1.5 orders of magnitude [12]. It can be predicted that codoping can also promote an increase in conductivity.…”