Overview of Approaches to Increase the Electrochemical Activity of Conventional Perovskite Air Electrodes

The progressive research trends in the development of low-cost, commercially competitive solid oxide fuel cells with reduced operating temperatures are closely linked to the search for new functional materials as well as technologies to improve the properties of established materials traditionally used in high-temperature devices. Significant efforts are being made to improve air electrodes, which significantly contribute to the degradation of cell performance due to low oxygen reduction reaction kinetics at reduced temperatures. The present review summarizes the basic information on the methods to improve the electrochemical performance of conventional air electrodes with perovskite structure, such as lanthanum strontium manganite (LSM) and lanthanum strontium cobaltite ferrite (LSCF), to make them suitable for application in second generation electrochemical cells operating at medium and low temperatures. In addition, the information presented in this review may serve as a background for further implementation of developed electrode modification technologies involving novel, recently investigated electrode materials. © 2023 by the authors.Russian Science Foundation, RSF: 23-23-00083The research funding from the Russian Science Foundation (agreement 23-23-00083) is gratefully acknowledged

Recent Progress in the Design, Characterisation and Application of LaAlO3-and LaGaO3-Based Solid Oxide Fuel Cell Electrolytes

Solid oxide fuel cells (SOFCs) are efficient electrochemical devices that allow for the direct conversion of fuels (their chemical energy) into electricity. Although conventional SOFCs based on YSZ electrolytes are widely used from laboratory to commercial scales, the development of alternative ion-conducting electrolytes is of great importance for improving SOFC performance at reduced operation temperatures. The review summarizes the basic information on two representative families of oxygen-conducting electrolytes: doped lanthanum aluminates (LaAlO3) and lanthanum gallates (LaGaO3). Their preparation features, chemical stability, thermal behaviour and transport properties are thoroughly analyzed in terms of their connection with the target functional parameters of related SOFCs. The data presented here will serve as a starting point for further studies of La-based perovskites, including in the fields of solid state ionics, electrochemistry and applied energy. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.Ministry of Education and Science of the Russian Federation, Minobrnauka: 075-03-2021-051/5Funding: This research was funded by to the Ministry of Education and Science of the Russian Federation, contract no. 075-03-2021-051/5

Short review on recent studies and prospects of application of rare-earth-doped La2NiO4+δ as air electrodes for solid-oxide electrochemical cells

Received: 16 October 2023. Accepted: 2 November 2023. Published online: 14 November 2023.Solid solutions based on the rare earth substituted lanthanum nickelate La2NiO4+δ are considered as promising air electrode materials for electrochemical applications. The present focus review summarizes recently published papers dealing with synthesis methods and investigations of the crystal structure, physicochemical properties, oxygen diffusion and electrochemical activity of La2–xLnxNiO4+δ (Ln = Pr, Nd, Sm, Eu, Gd) electrode materials. It highlights the application advantages and drawbacks of the Ln-substituted La2NiO4+δ for solid oxide fuel and electrolysis cells and compared to the non-substituted La2NiO4+δ.The authors are grateful to Mr. Roman Ivanov, engineer of the Department of Technical Physics, Physico-technological Institute UrFU, for help with the graphical visualization of data

Undoped sr2mmoo6 double perovskite molybdates (M = ni, mg, fe) as promising anode materials for solid oxide fuel cells

The chemical design of new functional materials for solid oxide fuel cells (SOFCs) is of great interest as a means for overcoming the disadvantages of traditional materials. Redox stability, carbon deposition and sulfur poisoning of the anodes are positioned as the main processes that result in the degradation of SOFC performance. In this regard, double perovskite molybdates are possible alternatives to conventional Ni-based cermets. The present review provides the fundamental properties of four members: Sr2NiMoO6-δ, Sr2MgMoO6-δ, Sr2FeMoO6-δ and Sr2Fe1.5Mo0.5O6-δ. These properties vary greatly depending on the type and concentration of the 3d-element occupying the B-position of A2BB’O6. The main emphasis is devoted to: (i) the synthesis features of undoped double molybdates, (ii) their electrical conductivity and thermal behaviors in both oxidizing and reducing atmospheres, as well as (iii) their chemical compatibility with respect to other functional SOFC materials and components of gas atmospheres. The information provided can serve as the basis for the design of efficient fuel electrodes prepared from complex oxides with layered structures. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.The work was funded by a grant from the Ministry of Science and Higher Education of the Russian Federation (Agreement No. 075-15-2019-1924)

Unusual Lattice Parameters Behavior for La1.9Ca0.1NiO4+δ at the Temperatures below Oxygen Loss

In this work, we studied the structural features of La1.9Ca0.1NiO4.11, which is considered a promising cathode material for intermediate temperature solid-oxide fuel cells (IT-SOFC). The effect of different pretreatments on the structural characteristics of the sample was studied using X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) in order to elucidate the origin of a peculiar change of lattice parameters observed earlier during in situ XRD studies. The XRD studies have shown that anisotropic broadening for reflections with a high Miller index l appears after tempering of a quenched (from 1100◦C) sample at 250◦C. This temperature is too low for the release/incorporation of oxygen into the structure but is sufficient for oxygen migration inside the structure. The HRTEM assisted us in revealing differences in the defect structure after different pretreatments. Based on obtained results, the following possible explanation was proposed. Observed additional microstrains and non-oriented planar defects as well as a decrease in the coherent scattering region size in the [00l] direction are caused by the non-homogeneous redistribution of interstitial oxygen in the structure during tempering. © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).Funding: The reported study was funded within the framework of budget project for Synchrotron radiation facility SKIF, Boreskov Institute of Catalysis. In the part of samples characterization by HRTEM technique the work was supported by the Ministry of Science and Higher Education of the Russian Federation within the governmental order for Boreskov Institute of Catalysis

CRYSTAL STRUCTURE AND PHASE TRANSITIONS OF THE PEROVSKITE-LIKE RARE-EARTH COMPLEX OXIDES

The high-temperature behavior of the lanthanum and praseodymium complex oxides was established using XRD analysis. The calculations of the configurational entropy and fixation factor of the entropy-stabilized materials were performed.This work was supported by the Russian Science Foundation (Project № 23-23-00083)

PHYSICO-CHEMICAL PROPERTIES OF LANTHANUM COMPOUNDS AS CATHODE MATERIALS FOR SOLID OXIDE FUEL CELLS

Calculations of the configurational entropy, fixation factors, crystal structure and electrochemical performance study of the perovskite-type and Ruddlesden-Popper phases on the base of the lanthanum and 3d-transition metal oxides are performed.This work was supported by the Russian Science Foundation (Project № 23-23-00083)

Affinity maturation generates greatly improved xyloglucan-specific carbohydrate binding modules

<p>Abstract</p> <p>Background</p> <p>Molecular evolution of carbohydrate binding modules (CBM) is a new approach for the generation of glycan-specific molecular probes. To date, the possibility of performing affinity maturation on CBM has not been investigated. In this study we show that binding characteristics such as affinity can be improved for CBM generated from the CBM4-2 scaffold by using random mutagenesis in combination with phage display technology.</p> <p>Results</p> <p>Two modified proteins with greatly improved affinity for xyloglucan, a key polysaccharide abundant in the plant kingdom crucial for providing plant support, were generated. Both improved modules differ from other existing xyloglucan probes by binding to galactose-decorated subunits of xyloglucan. The usefulness of the evolved binders was verified by staining of plant sections, where they performed better than the xyloglucan-binding module from which they had been derived. They discriminated non-fucosylated from fucosylated xyloglucan as shown by their ability to stain only the endosperm, rich in non-fucosylated xyloglucan, but not the integument rich in fucosylated xyloglucan, on tamarind seed sections.</p> <p>Conclusion</p> <p>We conclude that affinity maturation of CBM selected from molecular libraries based on the CBM4-2 scaffold is possible and has the potential to generate new analytical tools for detection of plant carbohydrates.</p

Mixed ionic-electronic conductivity, phase stability and electrochemical activity of Gd-substituted La2NiO4+δ as oxygen electrode material for solid oxide fuel/electrolysis cells

Ruddlesden-Popper La2-xGdxNiO4+δ (x = 0–0.4) nickelates were synthesized by glycerol-nitrate combustion technique and explored as potential oxygen electrode materials for solid oxide fuel/electrolysis cells. Similar to the parent La2NiO4+δ, the metastability of RP-type n = 1 structure limits the applicability of La2-xGdxNiO4+δ to temperatures below 900 °C. These solid solutions are mixed conductors with predominantly p-type electronic conductivity that exceeds 50 S/cm at 500–800 °C in air. Substitution by gadolinium does not change the overstoichiometric oxygen content in air but has a negative impact on the mobility of interstitial oxygen, most likely, due to steric effects associated with the lattice shrinkage on doping. The electrochemical activity of bilayer electrodes comprising functional La2-xGdxNiO4+δ and current collecting LaNi0.6Fe0.4O3-δ + 3 wt% CuO layers in contact with Ce0.8Gd0.2O1.9 electrolyte was studied in air at 550–850 °C. Analysis of electrochemical impedance spectroscopy data employing the ALS (Adler-Lane-Steele) model revealed the limiting role of oxygen-ionic conductivity of functional La2-xGdxNiO4+δ materials in overall electrode performance. © 2021 Hydrogen Energy Publications LLCCOMPETE2020IHTE UB RASFundação para a Ciência e a Tecnologia, FCTRussian Foundation for Basic Research, РФФИ, (20-03-00151, POCI-01-0145-FEDER-032295)Ministério da Ciência, Tecnologia e Ensino Superior, MCTES, (SFRH/BD/138773/2018, UIDB/50011/2020, UIDP/50011/2020)Government Council on Grants, Russian FederationSynthesis of the materials, XRD, BET and SEM study were performed using the equipment of the Shared Access Centre Composition of Compounds, IHTE UB RAS, with the support from the Government of the Russian Federation, Agreement No. 02.A03.21.0006 (Act 211). The electrochemical studies were supported financially by the Russian Foundation for Basic Research (RFBR), grant No. 20-03-00151. K.Z., D.B. and A.Y. gratefully acknowledge financial support by the project CARBOSTEAM (POCI-01-0145-FEDER-032295) funded by FEDER through COMPETE2020 - Programa Operacional Competitividade e Internacionalização (POCI) and by national funds through FCT/MCTES , and by project CICECO - Aveiro Institute of Materials ( UIDB/50011/2020 & UIDP/50011/2020 ) financed by national funds through the FCT/MCTES and when appropriate co-financed by FEDER under the PT2020 Partnership Agreement. K.Z. acknowledges PhD scholarship by the FCT ( SFRH/BD/138773/2018 )

Correlation between structural and transport properties of ca-doped la nickelates and their electrochemical performance

This work presents the results from a study of the structure and transport properties of Ca-doped La2NiO4+δ. La2−xCaxNiO4+δ (x = 0–0.4) materials that were synthesized via combustion of organic-nitrate precursors and characterized by X-ray diffraction (XRD), in situ XRD using synchrotron radiation, thermogravimetric analysis (TGA) and isotope exchange of oxygen with C18O2. The structure was defined as orthorhombic (Fmmm) for x = 0 and tetragonal (I4/mmm) for x = 0.1–0.4. Changes that occurred in the unit cell parameters and volume as the temperature changed during heating were shown to be caused by the excess oxygen loss. Typical for Ruddlesden–Popper phases, oxygen mobility and surface reactivity decreased as the Ca content was increased due to a reduction in the over-stoichiometric oxygen content with the exception of x = 0.1. This composition demonstrated its superior oxygen transport properties compared to La2NiO4+δ due to the enhanced oxygen mobility caused by structural features. Electrochemical data obtained showed relatively low polarization resistance for the electrodes with a low Ca content, which correlates well with oxygen transport properties. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.The materials synthesis as well as electrochemical study were performed in a framework of the budget task of the IHTE UB RAS with using the equipment of the shared access center “Composition of compounds”. The TGA and isotope exchange studies were supported by the Ministry of Science and Higher Education of the Russian Federation within the governmental order for Boreskov Institute of Catalysis (projects АААА‐А21‐121011390007‐7, АААА‐А21‐ 121011390009‐1). The SXRD experiments were performed at the shared research center SSTRC on the basis of the Novosibirsk VEPP‐3 complex at BINP SB RAS, using equipment supported by pro‐ ject RFMEFI62119X0022