La0.6Sr0.4Co0.2Fe0.8O3-δ/CeO2 Heterostructured Composite Nanofibers as a Highly Active and Robust Cathode Catalyst for Solid Oxide Fuel Cells

In situ self-assembled NdBa0.5Sr0.5Co2O5+δ/Gd0.1Ce0.9O2-δ hetero-interfaces enable enhanced electrochemical activity and CO2 durability for solid oxide fuel cells

The development of solid oxide fuel cells (SOFCs) faces impediments in terms of challenges associated with oxygen reduction activity and CO2 durability. Therefore, a series of novel composite cathode materials, consisting of NdBa0.5Sr0.5Co2O5+δ (NBSC) and Gd0.1Ce0.9O2-δ (GDC), were designed and synthesized using a one-pot strategy through a self-assembly process. The incorporation of GDC leads to a significant increase in the number of active sites. Furthermore, it alters the anisotropic transport properties of oxygen ions within layered double perovskite materials, consequently creating a three-dimensional conduit for O2- transportation. Simultaneously, the in-situ formation of closely intertwined heterogeneous interfaces between NBSC and GDC particles can facilitate the charge transfer processes and oxygen ion transport, thereby improving the kinetics of the oxygen reduction reaction (ORR). The NBSC-10GDC cathode, prepared through the one-pot method, exhibits reduced polarization resistances and enhanced CO2 tolerance in comparison to the mechanically mixed cathode. At 750 °C, the one-pot NBSC-10GDC exhibits a low area-specific resistance (ASR) of 0.029 Ω cm2, which is 69.8% lower than the ASR of single-phase NBSC and 42.0% lower than mechanically mixed NBSC-10GDC. Additionally, the one-pot NBSC-10GDC demonstrates a remarkable maximum power density (MPD) of 1.36 W cm-2 at 750 °C. These findings highlight the considerable potential of the one-pot NBSC-10GDC as a promising material for SOFC cathode.

Interfacial Disordering and Heterojunction Enabling Fast Proton Conduction

The interfacial disorder is a general method to change the metal-oxygen compatibility and carrier density of heterostructure materials for ionic transport modulation. Herein, to enable high proton conduction, a semiconductor heterostructure based on spinel ZnFe2 O4 (ZFO) and fluorite CeO2 is developed and investigated in terms of structural characterization, first principle calculation, and electrochemical performance. Particular attention is paid to the interfacial disordering and heterojunction effects of the material. Results show that the heterostructure induces a disordered oxygen region at the hetero-interface of ZFO-CeO2 by dislocating oxygen atoms, leading to fast proton transport. As a result, the ZFO-CeO2 exhibits a high proton conductivity of 0.21 S cm-1 and promising fuel cell power output of 1070 mW cm-2 at 510 °C. Based upon these findings, a new mechanism is proposed by focusing on the change of O-O bond length to interpret the diffusion and acceleration of protons in ZFO-CeO2 on the basis of the Grotthuss mechanism. This study provides a new strategy to customize semiconductor heterostructure to enable fast proton conduction.

Ultralow Loading of Ru as a Bifunctional Catalyst for the Oxygen Electrode of Solid Oxide Cells

The oxygen evolution reaction (OER) is a significant contributor to the cell overpotential in solid oxide electrolyzer cells (SOECs). Although noble metals such as Ru and Ir have been utilized as OER catalysts, their widespread application in SOECs is hindered by their high cost and limited availability. In this study, we present a highly effective approach to enhance air electrode performance and durability by depositing an ultrathin layer of metallic Ru, as thin as ∼7.5 Å, onto (La0.6Sr0.4)0.95Co0.2Fe0.8O3-δ (LSCF) using plasma-enhanced atomic layer deposition (PEALD). Our study suggests that the emergence of a perovskite, SrRuO3, resulting from the reaction between PEALD-based Ru and surface-segregated Sr species, plays a crucial role in suppressing Sr segregation and maintaining favorable oxygen desorption kinetics, which ultimately improves the OER durability. Further, the PEALD Ru coating on LSCF also reduces the resistance to the oxygen reduction reaction (ORR), highlighting the bifunctional electrocatalytic activities for reversible fuel cells. When the LSCF electrode of a test cell is decorated with ∼7.5 Å of the Ru overcoat, a current density of 656 mA cm-2 at 1.3 V in electrolysis mode and a peak power density of 803 mW cm-2 in fuel cell mode are demonstrated at 700 °C, corresponding to an enhancement of 49.1 and 31.9%, respectively, compared to the pristine cell.

Alumina Ceramic Nanofibers: An Overview of the Spinning Gel Preparation, Manufacturing Process, and Application

As an important inorganic material, alumina ceramic nanofibers have attracted more and more attention because of their excellent thermal stability, high melting point, low thermal conductivity, and good chemical stability. In this paper, the preparation conditions for alumina spinning gel, such as the experimental raw materials, spin finish aid, aging time, and so on, are briefly introduced. Then, various methods for preparing the alumina ceramic nanofibers are described, such as electrospinning, solution blow spinning, centrifugal spinning, and some other preparation processes. In addition, the application of alumina ceramic nanofibers in thermal insulation, high-temperature filtration, catalysis, energy storage, water restoration, sound absorption, bioengineering, and other fields are described. The wide application prospect of alumina ceramic nanofibers highlights its potential as an advanced functional material with various applications. This paper aims to provide readers with valuable insights into the design of alumina ceramic nanofibers and to explore their potential applications, contributing to the advancement of various technologies in the fields of energy, environment, and materials science.

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.

One-dimensional carbon based nanoreactor fabrication by electrospinning for sustainable catalysis

An efficient and economical electrocatalyst as kinetic support is key to electrochemical reactions. For this reason, chemists have been working to investigate the basic changing of chemical principles when the system is confined in limited space with nanometer-scale dimensions or sub-microliter volumes. Inspired by biological research, the design and construction of a closed reaction environment, namely the reactor, has attracted more and more interest in chemistry, biology, and materials science. In particular, nanoreactors became a high-profile rising star and different types of nanoreactors have been fabricated. Compared with the traditional particle nanoreactor, the one-dimensional (1D) carbon-based nanoreactor prepared by the electrospinning process has better electrolyte diffusion, charge transfer capabilities, and outstanding catalytic activity and selectivity than the traditional particle catalyst which has great application potential in various electrochemical catalytic reactions.

Uncovering the Enhancement Mechanism of the Oxygen Reduction Reaction on Perovskite/Ruddlesden-Popper Oxide Heterostructures (Nd,Sr)CoO3/(Nd,Sr)2CoO4 and (Nd,Sr)CoO3/(Nd,Sr)3Co2O7

Although the perovskite (Nd,Sr)CoO₃ (NSC₁₁₃)/Ruddlesden-Popper (R-P) oxide (Nd,Sr)₂CoO₄ (NSC₂₁₄) heterostructure is reported to improve the oxygen reduction reaction (ORR) activity by 2-3 orders of magnitude, the enhancement mechanism remains unclear. For the first time, we conclude that there are two main factors that can enhance the ORR activity: (1) Oxygen adsorbed on such heterostructures would gain more electrons, promoting the oxygen adsorption. (2) The more distant rock-salt layers on the heterointerfaces can facilitate the insertion of interstitial oxygen and form a high-speed transport channel of interstitial oxygen. Moreover, the perovskite/double-layered R-P oxide heterostructure, which has not been reported yet, is predicted to have better ORR performance than the perovskite/single-layered R-P oxide heterostructure. Our work elucidates the ORR enhancement mechanism on perovskite/R-P oxide heterostructures from the atomic level, which is demonstrated by experiments and, thus, is very meaningful for the development of high-performance electrochemical devices.

Suppressing the Surface Amorphization of Ba0.5Sr0.5Co0.8Fe0.2O3-δ Perovskite toward Oxygen Catalytic Reactions by Introducing the Compressive Stress

Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3-δ (BSCF) perovskite has been recognized as a promising oxygen evolution reaction (OER) catalyst due to its superior intrinsic catalytic activity. However, BSCF suffers from serious degradation during the OER process due to its surface amorphization caused by the segregation of A-site ions (Ba²⁺ and Sr²⁺). Herein, we construct a novel BSCF composite catalyst (BSCF-GDC-NR) by anchoring the gadolinium-doped ceria oxide (GDC) nanoparticles on the surface of a BSCF nanorod by a concentration-difference electrospinning method. Our BSCF-GDC-NR has greatly improved bifunctional oxygen catalytic activity and stability toward both oxygen reduction reaction (ORR) and OER compared with the pristine BSCF. The improvement of the stability can be related to that anchoring GDC on BSCF effectively suppresses the segregation and dissolution of A-site elements in BSCF during the preparation and catalytic processes. The suppression effects are ascribed to the introduction of compressive stress between BSCF and GDC, which greatly inhibits the diffusions of Ba and Sr ions. This work can give a guidance for developing the perovskite oxygen catalysts with high activity and stability.

Fabrication and Applications of Ceramic-Based Nanofiber Materials Service in High-Temperature Harsh Conditions—A Review

Ceramic-based nanofiber materials have attracted attention due to their high-temperature resistance, oxidation resistance, chemical stability, and excellent mechanical performance, such as flexibility, tensile, and compression, which endow them with promising application prospects for filtration, water treatment, sound insulation, thermal insulation, etc. According to the above advantages, we, therefore, reviewed the ceramic-based nanofiber materials from the perspectives of components, microstructure, and applications to provide a systematical introduction to ceramic-based nanofiber materials as so-called blankets or aerogels, as well as their applications for thermal insulation, catalysis, and water treatment. We hope that this review will provide some necessary suggestions for further research on ceramic-based nanomaterials.

Facile Approach for Improving the Interfacial Adhesion of Nanofiber Air Electrodes of Reversible Solid Oxide Cells

Nanofibers have great promise as a highly active air electrode for reversible solid oxide cells (ReSOCs); however, one thorny issue is how to adhesively stick nanofibers to electrolyte with no damage to the original morphology. Herein, PrBa_0.8Ca_0.2Co₂O_5+δ (PBCC) nanofibers are applied as an air electrode by a facile direct assembly approach that leads to the retention of most of the unique microstructure of nanofibers, and firm adhesion of the nanofiber electrode onto the electrolyte is achieved by applying electrochemical polarization. A single cell with the PBCC nanofiber air electrode exhibits excellent maximum power density (1.97 W cm^-2), electrolysis performance (1.3 A cm^-2 at 1.3 V), and operating stability at 750 °C for 200 h. These findings provide a facile means for the utilization of nanofiber electrodes for high-performance and durable ReSOCs.

High-Entropy Materials in SOFC Technology: Theoretical Foundations for Their Creation, Features of Synthesis, and Recent Achievements

In this review, recent achievements in the application of high-entropy alloys (HEAs) and high-entropy oxides (HEOs) in the technology of solid oxide fuel cells (SOFC) are discussed for the first time. The mechanisms of the stabilization of a high-entropy state in such materials, as well as the effect of structural and charge factors on the stability of the resulting homogeneous solid solution are performed. An introduction to the synthesis methods for HEAs and HEOs is given. The review highlights such advantages of high-entropy materials as high strength and the sluggish diffusion of components, which are promising for the use at the elevated temperatures, which are characteristic of SOFCs. Application of the medium- and high-entropy materials in the hydrocarbon-fueled SOFCs as protective layers for interconnectors and as anode components, caused by their high stability, are covered. High-entropy solid electrolytes are discussed in comparison with traditional electrolyte materials in terms of conductivity. High-entropy oxides are considered as prospective cathodes for SOFCs due to their superior electrochemical activity and long-term stability compared with the conventional perovskites. The present review also determines the prioritizing directions in the future development of high-entropy materials as electrolytes and electrodes for SOFCs operating in the intermediate and low temperature ranges.

Effect of MgO and Fe2O3 dual sintering aids on the microstructure and electrochemical performance of the solid state Gd0.2Ce0.8O2-δ electrolyte in intermediate-temperature solid oxide fuel cells

Solid state electrolytes have been intensively studied in the solid oxide fuel cells (SOFCs). The aim of this work is to investigate the effects of MgO and Fe2O3 dual sintering aids on the microstructure and electrochemical properties of solid state Gd0.2Ce0.8O2-δ (GDC) electrolytes, which are prepared by a sol-gel method with MgO and Fe2O3 addition to the GDC system. It is found that the addition of MgO and Fe2O3 can reduce the sintering temperature, increase densification and decrease the grain boundary resistance of the electrolyte. The 2 mol% MgO and 2 mol% Fe2O3 co-doped GDC (GDC-MF) exhibits the highest grain boundary conductivity. At 400°C, the grain boundary conductivity and total conductivity of GDC-MF are 15.89 times and 5.56 times higher than those of GDC. The oxygen reduction reaction (ORR) rate at the electrolyte/cathode interface of GDC-MF is 47 % higher than that of GDC. Furthermore, the peak power density of a single cell supported by GDC-MF is 0.45 W cm−2 at 700°C, 36.7% higher than that of GDC. Therefore, the GDC-MF should be a promising electrolyte material for intermediate-temperature solid oxide fuel cells (IT-SOFCs).

Nanofiber Composites as Highly Active and Robust Anodes for Direct-Hydrocarbon Solid Oxide Fuel Cells

Direct utilization of methane fuels in solid oxide fuel cells (SOFCs) is a key technology to realize the immediate inclusion of such high-efficiency fuel cells into the current electricity generation infrastructure. However, the broad commercialization of direct-methane fueled SOFCs is critically hindered by the inadequate electrode activity and their poor longevity, which primarily stems from the carbon build-up issues. To make the technology more competitive, a novel electrode structure that can dramatically improve the tolerance against coking is essential. Herein, we present highly active and robust core-shell nanofiber anodes, La_0.75Sr_0.25Cr_0.5Mn_0.5O₃@Sm_0.2Ce_0.8O_1.9 (LSCM@SDC), directly obtained with a single-nozzle electrospinning process through the use of two immiscible polymers. The intimate coverage of SDC on LSCM not only increases the active reaction sites but also promotes resistance toward carbon deposition and thermal aggregation. As such, the electrode polarization resistance obtained with LSCM@SDC NFs is among the lowest value ever reported with LSCM derivatives (∼0.11 Ω cm² in wet H₂ at 800 °C). The facile fabrication process of such complex heterostructures developed in this work is attractive for the design of not only SOFC electrodes but also other solid-state devices such as electrolysis cells, membrane reformers, and protonic cells.

BaCO3 Nanoparticles-Modified Composite Cathode with Improved Electrochemical Oxygen Reduction Kinetics for High-Performing Ceramic Fuel Cells

The effects of the electrochemical oxygen reduction reaction (ORR) on the surface of single-phase perovskite cathodes are well understood, but its potential for use in a complex system consisting of different material types is unexplored. Herein, we report how BaCO3 nanoparticles-modified La0.6Sr0.4Co0.2Fe0.8O3-δ-Gd0.2Ce0.8O2-δ (LSCF–GDC)-composite cathodes improved the electrochemical oxygen reduction kinetics for high-performing ceramic fuel cells. Both X-ray diffraction (XRD) and thermogravimetric analysis (TGA) studies reveal that BaCO3 is stable, and that it does not show any solid-state reaction with LSCF–GDC at SOFCs’ required operating temperature. The electrochemical conductivity relaxation (ECR) study reveals that during the infiltration of BaCO3 nanoparticles into LSCF–GDC, the surface exchange kinetics (Kchem) are enhanced up to a factor of 26.73. The maximum power density of the NiO-YSZ anode-support cell is increased from 1.08 to 1.48 W/cm2 via surface modification at 750 °C. The modified cathode also shows an ultralow polarization resistance (Rp) of 0.027 Ω.cm2, which is ~4.4 times lower than that of the bare cathode (~0.12 Ω.cm2) at 750 °C. Such enhancement can be attributed to the accelerated oxygen surface exchange process, possibly through promoting the dissociation of oxygen molecules via the infiltration of BaCO3 nanoparticles. The density functional theory (DFT) illustrates the interaction mechanism between oxygen molecules and the BaCO3 surface.

Zirconia- and ceria-based electrolytes for fuel cell applications: critical advancements toward sustainable and clean energy production

Solid oxide fuel cells (SOFCs) are emerging as energy conversion devices for large-scale electrical power generation because of their high energy conversion efficiency, excellent ability to minimize air pollution, and high fuel flexibility. In this context, this critical review has focussed on the recent advancements in developing a suitable electrolyte for SOFCs which has been required for the commercialization of SOFC technology after emphasizing the literature from the prior studies. In particular, the significant developments in the field of solid oxide electrolytes for SOFCs, particularly zirconia- and ceria-based electrolytes, have been highlighted as important advancements toward the production of sustainable and clean energy. It has been reported that among various electrolyte materials, zirconia-based electrolytes have the potential to be utilized as the electrolyte in SOFC because of their high thermal stability, non-reducing nature, and high mechanical strength, along with acceptable oxygen ion conductivity. However, some studies have proved that the zirconia-based electrolytes are not suitable for low and intermediate-temperature working conditions because of their poor ionic conductivity to below 850 °C. On the other hand, ceria-based electrolytes are being investigated at a rapid pace as electrolytes for intermediate and low-temperature SOFCs due to their higher oxygen ion conductivity with good electrode compatibility, especially at lower temperatures than stabilized zirconia. In addition, the most emerging advancements in electrolyte materials have demonstrated that the intermediate temperature SOFCs as next-generation energy conversion technology have great potential for innumerable prospective applications.

Facile Approach to Enhance Activity and CO2 Resistance of a Novel Cobalt-Free Perovskite Cathode for Solid Oxide Fuel Cells

Developing high-performance and cost-effective cathodes is ever-increasingly vital for the advancement of intermediate-temperature solid oxide fuel cells (IT-SOFCs). To facilitate the popularization of nonprecious metallic and cobalt-free oxygen reduction electrodes, herein, we propose a novel perovskite-based BaFeO_3-δ (BF) matrix, Ba_0.75Sr_0.25Fe_0.875Y_0.125O_3-δ (BSFY), as a highly active cathode for IT-SOFCs. To our satisfaction, the BSFY electrode showcases a low area-specific resistance of 0.063 Ω cm², as well as a high peak power density of 1288 mW cm^-2 at 600 °C, yielding a more than threefold improvement compared to that of its BF counterpart (371 mW cm^-2). The long-term durability test highlights its practicability under the IT operating condition. When tested in 10 vol % CO₂-containing air, the BSFY electrode exhibits impressive resistance against contaminants within 50 h (<0.4 Ω cm² with a deterioration rate of ∼0.00011 Ω cm² min^-1). Coupled with its reversible response between pure air and the contaminant, the BSFY cathode is expected to be a promising cobalt-free alternative with high CO₂ resistance for IT-SOFCs.

Flexible Ceramic Fibers: Recent Development in Preparation and Application

Flexible ceramic fibers (FCFs) have been developed for various advanced applications due to their superior mechanical flexibility, high temperature resistance, and excellent chemical stability. In this article, we present an overview on the recent progress of FCFs in terms of materials, fabrication methods, and applications. We begin with a brief introduction to FCFs and the materials for preparation of FCFs. After that, various methods for preparation of FCFs are discussed, including centrifugal spinning, electrospinning, solution blow spinning, self-assembly, chemical vapor deposition, atomic layer deposition, and polymer conversion. Recent applications of FCFs in various fields are further illustrated in detail, including thermal insulation, air filtration, water treatment, sound absorption, electromagnetic wave absorption, battery separator, catalytic application, among others. Finally, some perspectives on the future directions and opportunities for the preparation and application of FCFs are highlighted. We envision that this review will provide readers with some meaningful guidance on the preparation of FCFs and inspire them to explore more potential applications.

Progress and prospects of reversible solid oxide fuel cell materials

Reversible solid oxide fuel cell (RSOFC) is an energy device that flexibly interchanges between electrical and chemical energy according to people's life and production needs. The development of cell materials affects the stability and cost of the cell, but also restricts its market-oriented development. After decades of research by scientists, a lot of achievements and progress have been made on RSOFC materials. According to the composition and requirements of each component of RSOFC, this article summarizes the research progress based on materials and discusses the merits and demerits of current cell materials in electrochemical performance. According to the efficiency of different materials in solid oxide fuel cell (SOFC mode) and solid oxide electrolyzer (SOEC mode), the challenges encountered by RSOFC in the operation are evaluated, and the future development of RSOFC materials is boldly prospected.

Chemical Degradation of the La0.6Sr0.4Co0.2Fe0.8O3−δ/Ce0.8Sm0.2O2−δ Interface during Sintering and Cell Operation

A complete cell consisting of NiO-Ce0.8Sm0.2O3−δ//Ce0.8Sm0.2O3−δ//(La0.6Sr0.4)0.95Co0.2Fe0.8O3−δ elaborated by a co-tape casting and co-sintering process and tested in operating fuel cell conditions exhibited a strong degradation in performance over time. Study of the cathode–electrolyte interface after cell testing showed, on one hand, the diffusion of lanthanum from (La0.6Sr0.4)0.95Co0.2Fe0.8O3−δ into Sm-doped ceria leading to a La- and Sm-doped ceria phase. On the other hand, Ce and Sm diffused into the perovskite phase of the cathode. The grain boundaries appear to be the preferred pathways of the cation diffusion. Furthermore, a strontium enrichment was clearly observed both in the (La0.6Sr0.4)0.95Co0.2Fe0.8O3−δ layer and at the interface with electrolyte. X-ray photoelectron spectroscopy (XPS) indicates that this Sr-rich phase corresponded to SrCO3. These different phenomena led to a chemical degradation of materials and interfaces, explaining the decrease in electrochemical performance.

Effectively Promoting Activity and Stability of a MnCo2O4-Based Cathode by In Situ Constructed Heterointerfaces for Solid Oxide Fuel Cells

The development of multiphase composite electrocatalysts plays a key role in achieving the efficient and durable operation of intermediate-temperature solid oxide fuel cells (IT-SOFCs). Herein, a self-assembled nanocomposite is developed as the oxygen reduction reaction (ORR) catalyst for IT-SOFCs through a coprecipitation method. The nanocomposite is composed of a doped (Mn_0.6Mg_0.4)_0.8Sc_0.2Co₂O₄ (MMSCO) spinel oxide (84 wt %), an orthorhombic perovskite phase (11.3 wt %, the spontaneous combination of PrO₂ additives and spinel), and a minor Sc₂O₃ phase (4.7 wt %). The surface of the (Mn_0.6Mg_0.4)_0.8Sc_0.2Co₂O₄ phase is activated by the self-assembled nanocoating with many heterogeneous interfaces. Thence, the ORR kinetics is obviously accelerated and an area-specific resistance (ASR) of ∼0.11 Ω cm² is obtained at 750 °C. Moreover, a single cell with the cathode shows a peak power density (PPD) of 1144.1 mW cm^-2 at 750 °C, much higher than that of the cell with the MnCo₂O₄ cathode (456.2 mW cm^-2). An enhanced stability of ∼120 h (0.8 A cm^-2, 750 °C) is also achieved, related to the reduced thermal expansion coefficient (13.9 × 10^-6 K^-1). The improvement in ORR kinetics and stability can be attributed to the refinement of grains, the formation of heterointerfaces, and the enhancement of mechanical compatibility.

Elucidating the Role of Oxide-Oxide/Carbon Interfaces of CuOx-CeO2/C in Boosting Electrocatalytic Performance

Herein, we report the synthesis and bifunctional oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) activities of a CuO_x-CeO₂/C electrocatalyst (EC) with rich oxide-oxide and oxide-carbon interfaces. It not only demonstrates a smaller Tafel slope (65 mV dec^-1) and higher limiting current density (-5.03 mA cm^-2) but also exhibits an onset potential (-0.10 V vs Ag/AgCl) comparable to that of benchmark Pt/C. Besides undergoing the favorable direct four-electron ORR pathway, it unveils a loss of 23% of its initial current after 6 h of a stability test and a negative shift of 4 mV in the half-wave potential after the accelerated durability test compared to the corresponding current loss of 28% and negative shift of 20 mV for Pt/C. It also reveals remarkable OER activity in an alkaline medium with a low onset potential (0.20 V) and a smaller Tafel slope (177 mV dec^-1). The bifunctional ORR/OER activity of CuO_x-CeO₂/C EC can be ascribed to the synergistic effects, its unique structure with enriched oxygen vacancies owing to the presence of Ce⁴⁺/Ce³⁺, robust oxide-oxide and oxide-carbon heterointerfaces, and homogeneous dispersion of oxides over the carbon bed, which facilitates faster electronic conduction.

Developing Low-Cost, High Performance, Robust and Sustainable Perovskite Electrocatalytic Materials in the Electrochemical Sensors and Energy Sectors: “An Overview”

Since its discovery in 1839, research on the synthesis and application of perovskite materials has multiplied largely due to their suitability to be used in the fields of nanotechnology, chemistry and material science. Appropriate changes in composition or addition of other elements or blending with polymers may result in new hybrid and/or composite perovskite materials that will be applied in advanced fields. In this review, we have recapitulated the recent progress on perovskite nanomaterial in solar cell, battery, fuel cell and supercapacitor applications, and the prominence properties of perovskite materials, such as excellent electronic, physical, chemical and optical properties. We discussed in detail the synthesis and results of various perovskite hybrid nanomaterials published elsewhere. We have also discussed the results of various studies on these low dimensional composite nanomaterials in broad sectors such as electronics/optoelectronics, batteries, supercapacitors, solar cells and electrochemical sensors.

LaCrO3-Coated La0.6Sr0.4Co0.2Fe0.8O3-δ Core-Shell Structured Cathode with Enhanced Cr Tolerance for Intermediate-Temperature Solid Oxide Fuel Cells

La_0.6Sr_0.4Co_0.2Fe_0.8O_3-δ (LSCF) is a common cathode material for intermediate-temperature solid oxide fuel cells because of its excellent oxygen reduction reaction catalytic activity. However, the Cr-poisoning effect is a severe issue, causing electrochemical performance degradation. For the development of a LSCF-based cathode with excellent Cr tolerance, a LaCrO₃-coated LSCF core-shell structured (LCr@LSCF) cathode was prepared via the solution infiltration method. After the cathode was coated with a LCr shell, the long-term stability and Cr tolerance were obviously improved, at the price of sacrificing some electrochemical performance. The development of a LCr@LSCF cathode with eye-catching Cr tolerance is of great significance to the commercialization of LSCF.

Enhanced Anode Performance and Coking Resistance by In Situ Exsolved Multiple-Twinned Co-Fe Nanoparticles for Solid Oxide Fuel Cells

The broad and large-scale application of solid oxide fuel cells (SOFCs) technology hinges significantly on the development of highly active and robust electrode materials. Here, Ni-free anode materials decorated with metal nanoparticles are synthesized by in situ reduction of Fe-doping Sr₂CoMo_1-xFe_xO_6-δ (x = 0, 0.05, 0.1) double perovskite oxides under a reducing condition at 850 °C. The exsolved nanoparticles from the Sr₂CoMo_0.95Fe_0.05O_6-δ (SCMF0.05) lattice are Co-Fe alloys with rich multiple-twinned defects, significantly enhancing the catalytic activity of the SCMF0.05 anode toward the oxidation of H₂ and CH₄. The electrolyte-supported single cell with the reuduced SCMF0.05 anode reaches peak power densities as high as 992.9 and 652.3 mW cm^-2 in H₂ and CH₄ at 850 °C, respectively, while maintaining superior stability (∼50 h at 700 °C). The reduced SCMF0.05 anode also demonstrates excellent coking resistance in CH₄, which can be attributed to the increased oxygen vacancies due to Fe doping and the effective catalysis of multiple-twinned Co-Fe alloy nanoparticles for reforming of CH₄ to H₂ and CO. The findings in this work may provide a new insight for the design of highly active and durable anode catalysts in SOFCs.

Rare-earth-containing perovskite nanomaterials: design, synthesis, properties and applications

As star material, perovskites have been widely used in the fields of optics, photovoltaics, electronics, magnetics, catalysis, sensing, etc. However, some inherent shortcomings, such as low efficiency (power conversion efficiency, external quantum efficiency, etc.) and poor stability (against water, oxygen, ultraviolet light, etc.), limit their practical applications. Downsizing the materials into nanostructures and incorporating rare earth (RE) ions are effective means to improve their properties and broaden their applications. This review will systematically summarize the key points in the design, synthesis, property improvements and application expansion of RE-containing (including both RE-based and RE-doped) halide and oxide perovskite nanomaterials (PNMs). The critical factors of incorporating RE elements into different perovskite structures and the rational design of functional materials will be discussed in detail. The advantages and disadvantages of different synthesis methods for PNMs will be reviewed. This paper will also summarize some practical experiences in selecting suitable RE elements and designing multi-functional materials according to the mechanisms and principles of REs promoting the properties of perovskites. At the end of this review, we will provide an outlook on the opportunities and challenges of RE-containing PNMs in various fields.