Perovskite-structured Oxides Research Articles

In-situ prepared co exsolution nano catalyst for efficient hydrogen generation via ammonia decomposition

Active and durable catalytic material for ammonia (NH3) decomposition reaction is attracting attentions for utilization of NH3 as an innovative hydrogen carrier. In this study, diverse single metal and alloy nano catalysts are prepared via in-situ exsolution method and their NH3 decomposition properties are evaluated. Transition metal cations (Ni, Co, Fe ions) are doped into the La0.43Ca0.37MxNyTi1-(x+y)O3-δ (LCMNT) perovskite oxide structure and exsolved on its surface as supported nano particles under reduction condition. The maximum doping level and chemical composition of exsolution catalysts are investigated to optimize their NH3 decomposition activity. The exsolution catalyst demonstrates improved NH3 decomposition characteristics compared to conventionally prepared infiltration catalysts, indicating higher conversion efficiency and H2 production rate. The exsolved nano catalysts also exhibit great thermochemical stability against catalyst agglomeration or surface nitriding. The results obtained in this study suggest the potential utilization of exsolution catalysts for on-site production of H2 through NH3 decomposition catalysis.

Antiferromagnetic Chern insulator with large charge gap in heavy transition-metal compounds

Despite the discovery of multiple intrinsic magnetic topological insulators in recent years the observation of Chern insulators is still restricted to very low temperatures due to the negligible charge gaps. Here, we uncover the potential of heavy transition-metal compounds for realizing a collinear antiferromagnetic Chern insulator (AFCI) with a charge gap as large as 300 meV. Our analysis relies on the Kane-Mele-Kondo model with a ferromagnetic Hund coupling JH\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$J_{{\ extrm{H}}}$$\\end{document} between the spins of itinerant electrons and the localized spins of size S. We show that a spin-orbit coupling λSO≳0.03t\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\lambda _{{\ extrm{SO}}} \\gtrsim 0.03t$$\\end{document}, where t is the nearest-neighbor hopping element, is already large enough to stabilize an AFCI provided the alternating sublattice potential δ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\delta$$\\end{document} is in the range δ≈SJH\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\delta \\approx SJ_{{\ extrm{H}}}$$\\end{document}. We establish a remarkable increase in the charge gap upon increasing λSO\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\lambda _{{\ extrm{SO}}}$$\\end{document} in the AFCI phase. Using our results we explain the collinear AFCI recently found in monolayers of CrO and MoO with charge gaps of 1 and 50meV\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$50\\,\\hbox {meV}$$\\end{document}, respectively. In addition, we propose bilayers of heavy transition-metal oxides of perovskite structure as candidates to realize a room-temperature AFCI if grown along the [111] direction and subjected to a perpendicular electric field.

Transport properties of highly dense proton-conducting BaSn1−xInxO3−δ ceramics

Doped barium stannate belongs to the perovskite-structured complex oxides with proton transport capability. Such objects are of high interest in terms of their application in various protonic ceramic electrochemical cells. In the present work, In-doped barium stannate (BaSn1−xInxO3−δ, 0 ≤ x ≤ 0.4) materials were prepared and thoroughly characterized by structural, microstructural, and electrochemical techniques. The single-phase and high-dense ceramic materials were prepared by the conventional solid-state synthesis route over the entire doping range investigated. The chemical composition of these materials was found to be in close agreement with the nominal values, indicating no evaporation of Ba-, Sn-, or In-containing phases during sintering. The high-temperature electrochemical analysis showed that the ionic conductivity of BaSn1−xInxO3−δ gradually increases with increasing the In-content without reaching a concentration maximum, even for high dopant concentrations. The relatively high activation energy values indicate that this ionic conductivity is determined by oxygen-ionic transport, which, however, becomes predominantly protonic at reduced temperatures. The determination of bulk and grain boundary transport showed that both were improved with the In-doping. The possible reasons for these observations were discussed in detail in this work. Therefore, the obtained data are important for discovering the transport properties of stannates and their potential applications.

Strategic Design and Insights into Lanthanum and Strontium Perovskite Oxides for Oxygen Reduction and Oxygen Evolution Reactions.

Perovskite oxides exhibit bifunctional activity for both oxygen reduction (ORR) and oxygen evolution reactions (OER), making them prime candidates for energy conversion in applications like fuel cells and metal-air batteries. Their intrinsic catalytic prowess, combined with low-cost, abundance, and diversity, positions them as compelling alternatives to noble metal and metal oxides catalysts. This review encapsulates the nuances of perovskite oxide structures and synthesis techniques, providing insight into pivotal active sites that underscore their bifunctional behavior. The focus centers on the breakthroughs surrounding lanthanum (La) and strontium (Sr)-based perovskite oxides, specifically their roles in zinc-air batteries (ZABs). An introduction to the mechanisms of ORR and OER is provided. Moreover, the light is shed on strategies and determinants central to optimizing the bifunctional performance of La and Sr-based perovskite oxides.

Research progress of perovskite long afterglow materials

The mechanism and properties of perovskite long afterglow materials and their applications in biological imaging, information storage, anti-counterfeiting, and other fields.

Low-Index Facet Polyhedron-Shaped Binary Cerium Titanium Oxide for High-Voltage Aqueous Zinc-Vanadium Redox Flow Batteries.

Aqueous zinc-vanadium hybrid redox flow battery systems are an efficient strategy to address the problems of low voltage and high cost of conventional all-vanadium redox flow batteries. However, the low electrochemical activity of carbon-based electrodes toward a vanadium redox reaction limits the performance of redox flow batteries. In this study, polyhedral binary cerium titanium oxide (Ce2/3TiO3, CTO) is synthesized using molten salt synthesis. CTO is fabricated by adjusting the temperature and composition. Notably, the prepared CTO obtained at 1000 °C shows the highest catalytic activity for a VO2+/VO2+ redox reaction. Further, CTO is prepared as a composite electrocatalyst and applied to a high-voltage aqueous zinc-vanadium redox flow battery. The cell adopts an alkali zinc electrolyte containing a Zn/[Zn(OH)4]2- redox pair and exhibits a high operating voltage of 2.26 V. Remarkably, a zinc-vanadium redox flow battery using the composite electrocatalyst exhibits a high energy density of 42.68 Wh L-1 at 20 mA cm-2 and an initial voltage efficiency of 90.3%. The excellent cell performance is attributed to structural defects caused by A-site deficiency in the perovskite oxide structure as well as oxygen vacancies resulting from the low valence state of the metal ion, which enhance the catalytic activity of the vanadium ions.

Design, synthesis and formation mechanism of a novel entropy-stabilized perovskite oxide derived from barium cerate/zirconate

Through the use of the cluster-plus-glue atom model, we theoretically designed a novel perovskite-structured oxide (ABO3), derived from a barium cerate/zirconate, with the following chemical formula: Ba(Ce0.2Zr0.2Gd0.2La0.2Y0.2)O2.7. Given the five different cations on the B-site, we demonstrated that the novel system is an Entropy-Stabilized Perovskite Oxide, which exhibits a reversible transition from a single-phase to a multiphase system. By using a simple coprecipitation process, we were able to synthesize and then sinter a well-densified single-phase perovskite. In the present work, we discussed for the first time the complex interactions occurring among the involved species that, depending on the treatment conditions, could lead to the formation of either an entropy-stabilized orthorhombic perovskite or a metastable cubic perovskite.

Novel Design of Perovskite-Structured Neodymium Cobalt Oxide Nanoparticle-Embedded Graphene Oxide Nanocomposites as Efficient Active Materials of Energy Storage Devices.

In recent years, electrochemical supercapacitors are expected to represent the future of energy storage device technology. Specifically, the excellent electrochemical performance with long cycle life, high energy, and power density is considered an essential criterion for commercial applications. Herein, we constructed a novel composite of neodymium cobalt oxide-encapsulated graphene oxide nanocomposite (NCO/GO) via a simple and robust method for a symmetric supercapacitor (SSC) device. The prepared samples were securitized by X-ray diffraction, Fourier transform infrared spectroscopy, Raman, X-ray photoelectron spectroscopy, field emission scanning electron microscopy, high-resolution transmission electron microscopy, and Brunauer-Emmett-Teller analysis. The as-synthesized NCO/GO is deposited on nickel foam (NF) and used as a supercapacitor electrode (NCO/GO/NF), which exhibits superior specific capacitance (Cs) of 1080.92 F g-1 at 1 A g-1 and fantastic cycling life with ∼89.42% retention after 10,000 cycles at 10 A g-1 in 1.0 M KOH aqueous electrolyte. A tremendous electrochemical performance of the hybrid nanocomposite electrode is obtained from the good redox activity and synergistic effects of the NCO spherical-like nanoparticles combined with the GO nanosheets. Furthermore, the assembled SSC device delivers significantly enhanced power density (932.93 Wh kg-1) and energy density (210.42 mWh kg-1). Moreover, the SSCs exhibit excellent cycling stability with ∼82.19% capacity retaining over 10,000 charge/discharge cycles. Remarkably, a 1.8 V red light-emitting diode (LED) can be lit up for more than 10 min by series connection SSCs. Thus, the obtained results indicated that the NCO/GO/NF//NCO/GO/NF symmetric device has a robust and cost-effective electrode material for high-performance supercapacitor systems.

Enhancing the oxygen reduction reaction activity of SOFC cathode via construct a cubic fluorite/perovskite heterostructure

Pr2NiO4+δ-based (Ruddlesden-Popper) perovskite-structured oxide materials are promising candidates for low and intermediate temperature solid oxide fuel cells (SOFCs) systems. In this study, we prepared a high-performance cubic-fluorite/perovskite heterostructure Pr6O11-Pr1.2Sr0.8NiO4+δ (PO-PSNO) cathode for intermediate temperature SOFCs by solution impregnation method. By changing the impregnation amount of Pr6O11, the micro-morphology of the heterostructure was regulated, so that the heterostructure interface had the best reactive site. The oxygen reduction reaction (ORR) performance of Pr1.2Sr0.8NiO4+δ is improved, and the content of surface Sr in the heterostructure electrode material is reduced. Our results indicate that the synergistic effect of PO particles and PSNO skeleton makes the heterostructure exhibit a high oxygen surface exchange properties and catalytic performance. When the impregnation amount of PO particles reaches about 10% of the PSNO skeleton, the heterostructure has the best ORR activity. The oxygen surface exchange coefficient (Kchem) of 2-PO-PSNO is 5.8 × 10-4 cm·s−1, being 1.45 times as that of PSNO at 750 °C. Meanwhile, the polarization impedance (Rp) of 2-PO-PSNO is reduced by 66% to only 0.114 Ω cm2. Our study provides a new approach for developing high-performance RP structured perovskite cathodes and demonstrates practical applications in the field of SOFCs.

Cu-Content La1−XSrxNi1−YCuyO3−Δ Perovskites As Cobalt-Free Cathode Materials for High-Performance It-SOFCs

Solid Oxide Fuel Cells (SOFCs) are one of the most attractive energy conversion and storage devices, which can be applied for decentralized energy applications. However, the high operating temperature making SOFCs still unmarketable, which indicates that lowering the working temperature of SOFCs while still maintaining a high-power output is very crucial. For Intermediate-Temperature Solid Oxide Fuel Cells (IT-SOFCs), new cathode materials with high electrocatalytic activity and stability are necessary to provide a stable and high performance of cells. Perovskite-structured oxide (ABO3−δ) is one group of the most interesting material candidates for IT-SOFCs, presenting great potential in chemical composition modifications, yielding the design and gain of desired physicochemical and electrochemical properties [1]. The simple perovskite LaCuO3 is one of the well-studied Cu-content oxides with a high conductivity (106 S·cm−1), but it can be hardly obtained and suffers with stability issues in air [1, 2]. To stabilize the perovskite structure and to improve electrochemical properties of Cu-content oxides A-site and B-site modification strategy can be applied. It has been noted that Cu- and Ni-containing LaNi0.5Cu0.5O3−δ simple perovskite possesses low cathodic polarization of 0.056 Ω·cm2 at 800 °C, and a high power output of 870 mW·cm−2 at 900 °C [1, 3]. The generation of oxygen vacancies by strontium doping contributes to the increase of ionic conductivity component, and the Sr dopant can reduce the oxygen vacancy formation energy and increase the ionic conductivity of La1−xSrxMO3−δ (M = Fe, Mn) perovskites [1,4]. Therefore, in this work, Cu-content La1−xSrxNi1−yCuyO3−δ oxides with strontium doping at the A-site were evaluated as very promising Co-free cathode material candidates for IT-SOFCs.In this work, all La1−xSrxNi1−yCuyO3−δ compounds have been successfully obtained using soft chemistry. The room-temperature crystal structure of all oxides was assigned to the R-3c trigonal system. The substitution of La with Sr lowers the phase transition temperature from the R-3c space group to Pm-3m simple perovskite while increases the oxygen non-stoichiometry and the thermal expansion coefficient of studied materials. All investigated materials are chemically compatible with GDC-10, while unstable in contact with LSGM and 8YSZ. The manufactured anode-supported IT-SOFC with the La0.95Sr0.05Ni0.5Cu0.5O3−δ cathode presents an excellent power density of 445 mW·cm−2 at 650 °C in humidified H2. The results confirmed that La1−xSrxNi1−yCuyO3−δ perovskites can be potentially qualified as promising cathode candidates for IT-SOFCs, yielding promising electrochemical performance in the intermediate-temperature range [1].

Exsolution Synthesis of Alloyed Nanoparticles from Perovskite Oxide by Plasma

Bimetallic alloy nanoparticles (NPs) exsolved on the surface of perovskite oxides (ABO3) alter the structural and electronic properties of the primarily monometallic counterparts. These synergistic effects make the whole material present superior electrolytic and catalytic performances. The strong bonding interaction between alloy NPs and perovskite substrate enables the stability and durability of the catalysis.However, traditional thermal exsolution requires a long-time treatment at a high temperature. Researchers have been pursuing more time-saving and energy-efficient alternative routes. Herein, a low-temperature and fast pathway based on the dielectric barrier discharge (DBD) reactor is provided to in-situ exsolve alloy NPs. A favorable activity of the catalyst for CO oxidation is demonstrated. Additionally, we conclude that the factor restricts metallic agglomeration is the morphology of the substrate. Even after an overtime plasma treatment, the exsolved alloy NPs are still embedded in the porous structure of perovskite oxides.

Thin La doped CaMnO3 ceramics for attenuation−impedance balance to facilitate excellent microwave absorption

The perovskite structure oxide, CaMnO3, has been extensively investigated and applied as a potential microwave absorption material due to its versatile dielectric and spontaneous polarization. However, the low conductivity of pure CaMnO3 material limits its further application. Herein, to increase dielectric loss and achieve better microwave absorption properties, lanthanum (La)-doped CaMnO3 (Ca1-xLaxMnO3) ceramics were fabricated by a high temperature solid state reaction. The results of XRD and XPS show that the La atom was efficiently doped at the Ca site in CaMnO3, which carries excess positive charges and affects the valence state of Mn ions and the concentration of oxygen vacancies. Therefore, the conductivity and imaginary permittivity of Ca1-xLaxMnO3 ceramics increased dramatically with La-doped content. Benefiting from the tunable dielectric and impedance properties, Ca1-xLaxMnO3 ceramics can be utilized in a highly efficient way to absorb microwave radiation with a thin thickness. The sample with x = 0.04 shows the best microwave absorption property, with an RLmin value of -52.63 dB (d = 1.41 mm) and effective absorption bandwidth coves full X band in the thickness range from 1.315 mm to 1.395 mm.

Center-environment deep transfer machine learning across crystal structures: from spinel oxides to perovskite oxides

In data-driven materials design where the target materials have limited data, the transfer machine learning from large known source materials, becomes a demanding strategy especially across different crystal structures. In this work, we proposed a deep transfer learning approach to predict thermodynamically stable perovskite oxides based on a large computational dataset of spinel oxides. The deep neural network (DNN) source domain model with “Center-Environment” (CE) features was first developed using the formation energy of 5329 spinel oxide structures and then was fine-tuned by learning a small dataset of 855 perovskite oxide structures, leading to a transfer learning model with good transferability in the target domain of perovskite oxides. Based on the transferred model, we further predicted the formation energy of potential 5329 perovskite structures with combination of 73 elements. Combining the criteria of formation energy and structure factors including tolerance factor (0.7 < t ≤ 1.1) and octahedron factor (0.45 < μ < 0.7), we predicted 1314 thermodynamically stable perovskite oxides, among which 144 oxides were reported to be synthesized experimentally, 10 oxides were predicted computationally by other literatures, 301 oxides were recorded in the Materials Project database, and 859 oxides have been first reported. Combing with the structure-informed features the transfer machine learning approach in this work takes the advantage of existing data to predict new structures at a lower cost, providing an effective acceleration strategy for the expensive high-throughput computational screening in materials design. The predicted stable novel perovskite oxides serve as a rich platform for exploring potential renewable energy and electronic materials applications.

Lattice Oxygen Regulation of Perovskites for Chemical Looping Oxidative Dehydrogenation of Ethylbenzene to Styrene

The direct dehydrogenation process produces over 90% of global styrene. However, it is hampered by high energy consumption due to equilibrium limitation, a high steam/ethylbenzene feeding ratio, and complicated separation procedures. In this study, we propose the synthesis of a novel perovskite-structured metal oxide as the redox catalyst for chemical looping oxidative dehydrogenation (CL-ODH) of ethylbenzene into styrene. Lower ethylbenzene activation temperature and higher oxygen storage capacity contributing to high ethylbenzene conversion are achieved by Mn doping of the B site in SrFeO3−δ, and styrene yield is further enhanced by Ba doping of the A site. The optimized Sr0.8Ba0.2Fe0.2Mn0.8O3−δ catalyst exhibits favorable dehydrogenation activity but is deactivated in the first five redox cycles due to the severe carbonation and perovskite structure decomposition. The decarbonization treatment on the catalyst at 950 °C in an O2 atmosphere restores the perovskite structure and dehydrogenation activity, resulting in 85% ethylbenzene conversion and 89% styrene selectivity at 550 °C. Ethylbenzene on the catalyst undergoes full combustion via adsorbed oxygen, ODH of ethylbenzene into styrene and H2O using lattice oxygen, and direct dehydrogenation without available lattice oxygen. The proposed redox catalyst demonstrates efficient conversion of ethylbenzene into styrene, showing great potential for the energy conservation and process intensification of styrene production.

Cerium-Based Perovskite Mixed Metal Oxide as the Radical Scavenger for PEM Fuel Cells Operating under Low Humidity Conditions.

When the polymer electrolyte membrane fuel cell (PEMFC) is operated under low humidity, the proton conductivity decreases due to membrane dehydration, causing adverse effects on fuel cell performance. Introducing appropriate additives to the membrane and catalyst layer to prevent membrane degradation at low humidity brings significant performance improvements to proton exchange membrane fuel cells. We developed a perovskite-structured multi-metal oxide Ce0.667Zr0.05Ti0.95O3-δ (CZTO) with high radical scavenging properties and good structural stability. The nanostructured ceramic CZTO is introduced into the membrane and cathode catalyst layer to improve the durability of the membrane electrode assembly. The Nafion-CZTO membrane exhibited maximum power densities of 1298 and 519 mW cm-2 at 100 and 20% relative humidity, respectively. The improved performance of Nafion-CZTO membranes over commercial Nafion membranes is due to the high proton conductivity and better radical scavenging properties of the CZTO additive. In addition, the expected positive effects of applying CZTO additives to the catalyst layer are verified by low charge transfer resistance and high electrochemical surface activity of the CZTO catalyst through electrochemical impedance spectroscopy and electrochemical surface area analyses.

Thermochemical Activity of Single- and Dual-Phase Oxide Compounds Based on Ceria, Ferrites, and Perovskites for Two-Step Synthetic Fuel Production.

This study focuses on the generation of solar thermochemical fuel (hydrogen, syngas) from CO2 and H2O molecules via two-step thermochemical cycles involving intermediate oxygen-carrier redox materials. Different classes of redox-active compounds based on ferrite, fluorite, and perovskite oxide structures are investigated, including their synthesis and characterization associated with experimental performance assessment in two-step redox cycles. Their redox activity is investigated by focusing on their ability to perform the splitting of CO2 during thermochemical cycles while quantifying fuel yields, production rates, and performance stability. The shaping of materials as reticulated foam structures is then evaluated to highlight the effect of morphology on reactivity. A series of single-phase materials including spinel ferrite, fluorite, and perovskite formulations are first investigated and compared to state-of-the-art materials. NiFe2O4 foam exhibits a CO2-splitting activity similar to its powder analog after reduction at 1400 °C, surpassing the performance of ceria but with much slower oxidation kinetics. On the other hand, although identified as high-performing materials in other studies, Ce0.9Fe0.1O2, Ca0.5Ce0.5MnO3, Ce0.2Sr1.8MnO4, and Sm0.6Ca0.4Mn0.8Al0.2O3 are not found to be attractive candidates in this work (compared with La0.5Sr0.5Mn0.9Mg0.1O3). In the second part, characterizations and performance evaluation of dual-phase materials (ceria/ferrite and ceria/perovskite composites) are performed and compared to single-phase materials to assess a potential synergistic effect on fuel production. The ceria/ferrite composite does not provide any enhanced redox activity. In contrast, ceria/perovskite dual-phase compounds in the form of powders and foams are found to enhance the CO2-splitting performance compared to ceria.

Investigation of Ba doping in A-site deficient perovskite Ni-exsolved catalysts for biogas dry reforming

This work presents the development of an A-site deficient La0.9−xBaxAl0.85Ni0.15O3 (x = 0, 0.02, 0.04, and 0.06) perovskite oxide catalyst for dry reforming of model biogas. The catalysts are prepared using a citrate sol-gel method and used for biogas dry reforming at 800 °C for feed ratios (CH4/CO2) of 1.5 and 2.0. The fresh and spent catalysts are analyzed using XRD, FTIR, TPD, XPS, FESEM, TEM, TPR, TGA-DTA, and Raman analysis. The XRD analysis exhibits the host perovskite oxide structure and the exsolved Ni phase for all prepared catalysts. The partial doping of Ba improves the metal support interaction and oxygen vacancies that enhance catalytic activity and stability, as revealed by the TPR and XPS analysis. The stability experiment on La0.9−xBaxAl0.85Ni0.15O3, for x = 0 catalyst resulted in reduced activity due to the catalyst deactivation by sintering, as confirmed by XRD and FE-SEM. Among all the catalysts studied, La0.84Ba0.06Al0.85Ni0.15O3 (LB6AN-15) exhibited the highest catalytic stability with CH4, and CO2 conversions are 60% and 93%, respectively, for 40 h time-on-stream due to the strong metal support interactions, high oxygen vacancies, and anti-sintering of exsolved Ni nanoparticles in biogas dry reforming.

Crystal Facet and Electronic Structure Modulation of Perovskite Oxides for Water Oxidation

In water-splitting catalysts, exposing high-activity crystal facets with optimal electronic structures can significantly enhance the oxygen evolution reaction (OER) kinetics. In this work, we demonstrate a facile strategy for simultaneously modulating the preferential crystal facet and electronic structure of perovskite oxides for their use as water-electrolysis catalysts using a template-mediated growth approach. Experimental and computational analyses revealed that the preferred crystal facet of La0.5Sr0.5CoO3 (LSC) grown on MoReS2 was effectively modulated to the (110) plane, and the free energy barrier of the rate-determining step was lowered by such crystal facet engineering. Furthermore, the interfacial charge transfer between LSC and MoReS2 enabled the optimal electronic structure of the B-site cation in LSC. Consequently, LSC grown on MoReS2 exhibited an OER activity of 210 mV at 10 mA cm–2, surpassing the performance of state-of-the-art perovskite oxide-based catalysts. Our findings provide new insights into the design of efficient perovskite oxide-based electrocatalysts for water electrolysis.

Controlled properties of perovskite oxide films by engineering oxygen octahedral rotation

Complex perovskite oxides exhibit extremely rich physical properties in terms of magnetism, electrical transport, and electrical polarization characteristics due to the competition and coupling of many degrees of freedom. The B-site ions and O ions in perovskite form six-coordinated octahedral units, which are connected at a common vertex toward the basic framework of the perovskite oxide, providing a crucial platform to tailor physical properties. The rotation or distortion of the oxygen octahedra will tip the competing balance, leading to many emergent ground states. To further clarify the subtle relationship between emergent properties and oxide octahedral behavior, this article reviews the structure of perovskite oxides, the characterization methods of oxygen octahedral rotation and the response of transport, electrical polarization and magnetism of several typical perovskite heterostructures to oxygen octahedral rotation modes. With knowledge of how to manipulate the octahedral rotation behavior and regulate the physical properties of perovskite oxides, rationally designing the sample manufacturing process can effectively guide the development and application of novel electronic functional materials and devices.

(Digital Presentation) ORR/OER Activity and Rechargeable Zinc-Air Battery Performance of B Site Doped Double Perovskite NdBaCoXO5+δ (X= Fe, Ni, Mn)

Renewable energy systems and designing economically viable electrochemical energy storage systems is essential to decrease environmental pollution concerns while meeting the growing energy demand. Among the various energy storage devices, rechargeable zinc-air batteries (RZAB) have attracted great attention due to their relatively high specific energy (1218 W.h/kg), and volumetric energy density (6136 W.h/L) cost-effectiveness, and environmental friendliness, comparable to that of lithium–air batteries [1]. However, the sluggish kinetics of the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) during the discharge and recharge process of the air cathode on RZAB prevents large-scale application. So far noble metals (Pt, Ru, Ir) and their alloys (Pt-Ru/C) are used as bifuctional oxygen electrocatalysts in commercial rechargeable RZAB, yet they are too expensive to be viable for large-scale commercial applications. Therefore, designing robust and cost-effective bifunctional oxygen electrocatalysts is prime of importance for RZAB to be commercialized [2]. One of the most promising oxygen bifunctional catalyst are perovskite oxides due to their structural and compositional flexibility [3]. Moreover, the electronic structure of perovskite oxides can be tuned by varying the transition metals at the B site and thus their electrocatalytic performance [4-5].In this work, first we will demonstrate phase pure fabrication of double perovskite oxide series of NdBaCoXO5+δ (X= Fe, Ni, Mn). Second, OER and ORR performances of the series of NdBaCoXO5+δ (X= Fe, Ni, Mn) will be explained in relation with their electronic structure and work function. Here, we applied NdBaCoMnO6 on a home-made RZAB as air cathode, according to its bifunctional index. Therefore, we will finally present charge-discharge performance of RZAB with NdBaCoMnO6 as air cathode. J. Fu, Z. P. Cano, M.G. Park, A. Yu, M. Fowler, Z. Chen, Advanced Materials, 29, 1604685 (2016).Y. Tong, J. Wu, P. Chen, H. Liu, W. Chu, C. Wu, Y. Xie, Journal of the American Chemical Society, 140, 11165-11169 (2018).W. Yin, B. Weng, J. Ge, Q. Sun, Z. Li, Y. Yan, Energy & Environmental Science, 12, 442-462 (2019).J. Ahmed, N. Alhokbany, M. Ubaidullah, S. Mutehri, M. M. Khan, S. M. Alshehri, Ceramics International, 46, 20038-20044 (2020).A. Mulder, N. Benedek, J. Rondinelli and C. Fennie, Advanced Functional Materials, n/a-n/a (2013).