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The Mn-doped BaCeO 3 series composite oxide catalysts were prepared by a sol-gel method. The low-temperature catalytic methane combustion activity test of BaCe 1-x Mn x O 3-δ series composite oxide catalysts at low temperature (200-600 °C) was studied in a fixed bed reactor. The physical properties of the catalyst were characterized by XRD, SEM, particle size analysis and specific surface area measurement, and the conductivity of the sample was measured by AC impedance spectroscopy. Research shows that: the perovskite phase composite oxide catalyst was successfully prepared by the sol-gel method, and the prepared perovskite phase catalyst has good catalytic performance and high temperature stability. The catalytic performance of the catalyst changes with the conductivity, which shows a proportional relationship; when the temperature is lower than 650 °C, Mn doping significantly improves the catalytic activity of the BaCeO 3 catalyst for methane combustion. The catalytic activity increases initially and then decreases with the doping amount of Mn. When the doping amount is 0.4 the catalyst has the best catalytic activity, with the ignition temperature of methane at as low as 249.7 °C, and the catalytic methane complete conversion temperature T 90 (The corresponding temperature when CH 4 conversion rate is 90%) at 423.2 °C. This work is of considerable referential importance in the optimization design of catalysts for CH 4 combustion at low temperature. [ABSTRACT FROM AUTHOR]

Membrane technologies have been widely investigated for CO 2 separation, especially inorganic membranes which could overcome the barrier of low melting point, and then been applied for combustion activities. Compared with molecular sieving membranes (MSMs), the mechanism during CO 2 separation process on electrolyte membranes (EMs) is more complicated. Mixed ionic and electronic conductors, such as perovskite oxides, has been proved with superior activity than oxygen ion conductors because of the additional surface reaction path. To further demonstrate the applicability of perovskite oxides contained membrane for CO 2 separation, in this work, CO 2 transport via La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ and carbonates composite membrane with hollow fiber microstructure was thoroughly investigated under various gas flow directions. This membrane presents the best permeability when CO 2 +N 2 (feed gas) flows at shell side and He (sweep gas) flows at tube side in parallel model. In addition, it also presents excellent thermal shock resistance after six times rising and cooling operation with almost no performance degradation. [ABSTRACT FROM AUTHOR]

Composite ceramic membrane is one of the most attractive concepts which combines the advantages of different phases into a single membrane matrix. Recently, the reported significant increased oxygen surface kinetics on the Perovskite/Ruddlesden-Popper composite system because of the formation of novel and fast oxygen transport paths along the hetero-interface has been implanted into the oxygen permeation membrane system. In this work, a novel La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ -(La 0.5 Sr 0.5) 2 CoO 4+δ (LSCF-LSC) composite hollow fiber membrane is synthesized with oxygen permeation flux of 4.52 mL min−1 cm−2 at 950 °C. It presents round 4 times and 2.3 times of that of the single LSCF membrane and LSC-coated LSCF membrane at 900 °C. For better comparison, (La 0.576 Sr 0.424) 1.136 Co 0.3 Fe 0.7 O 3-δ (LSCF-new) is prepared based on the composition of LSCF-LSC composite. The enhanced oxygen permeability was further investigated through electrochemical impedance spectroscopy (EIS) measurements. We also confirm that LSCF-LSC shows significantly lower area specific resistance (ASRs) for LSCF-LSC|Ce 0.8 Sm 0.2 O 1.9 (SDC)|LSCF-LSC symmetrical cell relative to other symmetrical cells. This novel LSCF-LSC composite membrane also presents high CO 2 tolerance, with stable oxygen permeation fluxes round 2.6 mL min−1 cm−2 at 900 °C for 100 h. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • La 0.6 Sr 0.4 CoO 3 hollow fibers with distinct macrostructures were characterized. • Ruddlesden–Popper oxide (La,Sr) 2 CoO 4 was applied as surface decoration. • Oxygen flux was enhanced by up to 47-fold by macrostructure modification. • Oxygen flux was enhanced by up to 25-fold by surface decoration. • The decorated La 0.6 Sr 0.4 CoO 3 hollow fiber showed stable flux for 160 h. Abstract Oxygen-selective perovskite hollow fiber membrane can be used to obtain an effective oxygen separation from air at high temperature (above 700 °C) for large scale application. Here, we display that oxygen permeation fluxes of La 0.6 Sr 0.4 CoO 3 (LSC 113 ) hollow fiber membrane was enhanced by macrostructure modification and (La,Sr) 2 CoO 4 (LSC 214 ) surface decoration. By changing the cross-section macrostructure from sandwich structure (for LSC-a fiber) to asymmetric structure (for LSC-b fiber), the oxygen flux was improved by up to 3.6-fold. Applying porous LSC 214 decoration on LSC 113 furthermore enhanced the oxygen fluxes for LSC-a and LSC-b, by up to 6.8-fold and 1.9-fold, respectively. [ABSTRACT FROM AUTHOR]

Asymmetric dense La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3−δ hollow fiber membranes were prepared by the joint phase inversion and sintering processes. Surface treatment by hydrochloric acid-etching and decoration of dispersed porous (La 0.5 Sr 0.5 ) 2 CoO 4+δ thin layer, was applied to improve the surface exchange reaction kinetics of oxygen reduction. Oxygen permeation performance of the unmodified and modified membranes was investigated under different operating conditions. Experimental results indicate that both surface treatment strategies effectively accelerate the oxygen permeation rate of the resultant membranes by the improved surface exchange kinetics; in particular, the oxygen fluxes were enlarged from 0.036 to 1.021 ml min −1 cm −2 of the bare membrane to 0.201–1.311 ml min −1 cm −2 of the decorated membrane by (La 0.5 Sr 0.5 ) 2 CoO 4+δ with a minimum improvement percentage of 28% when operation temperature varied from 700 to 1000 °C with helium flow rate of 150 ml min −1 . Furthermore, better flux enhancement of the surface-modified membrane was observed at lower temperature regimes than at higher temperatures indicates at lower temperatures the surface exchange reaction kinetics play a larger role in controlling the overall oxygen transport through the membrane; in other words, the relative limiting effect of the ionic bulk diffusion becomes more noticeable at higher temperatures. In addition to the significant oxygen flux improvement, the surface decorated membrane also displays high permeation stability under the investigated operating conditions. [ABSTRACT FROM AUTHOR]

Using solar energy to catalyse photo-driven processes to address the energy crisis and environmental pollution plays a role in the path to a sustainable society. Many oxide-based materials, especially perovskite oxides, have been widely investigated as catalysts for photocatalysis in energy and environment because of the low-cost and earth-abundant and good performance. At this stage, there is a need to present a scientific-based evaluation of the technologies developed so far and identify the most sustainable technologies and the existing limitations and opportunities for their commercialisation. This work comprehensively investigated the outcomes using various scientometric indices on perovskite oxide-based photo(electro)catalysts for water splitting, nitrogen fixation, carbon dioxide conversion, organic pollutant degradation, current trends and advances in the field. According to the results achieved, efforts in both energy and environment based on perovskite oxides have been initiated in the 1990s and accelerated since the 2010s. China and the United States were identified as the most contributing countries. Based on the results achieved in this study, the main milestones and current trends in the development of this field have been identified. The aim of this research is to provide useful guidelines for the further investigation of perovskite oxide-based catalysts for photoelectrocatalysis and photocatalysis both in energy and environment on the applications such as water splitting, nitrogen fixation, carbon dioxide conversion, and wastewater treatment. [ABSTRACT FROM AUTHOR]

Water splitting for renewable energy technologies necessitates the creation of low-cost, highly active, and stable electrocatalysts for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), which remains a challenging issue. Oxide-based catalysts, especially perovskites (ABO 3), ruddlesden–popper perovskite (A 2 BO 4) and pyrochlore-type oxides (A 2 B 2 O 7), have attracted gotten much interest as electrocatalysts for water splitting because of their distinctive physical, chemical, and electronic properties. In this work, a scientometric analysis is conducted on developing various oxide-based catalysts for water splitting to explore further developments. Up to now, a total of 29,761 publications (between the years 1990–2020) have been obtained from the Web of Science (WoS) website by searching for these written documents on this subject with a variety of linking keywords. The derived documents were subjected to a scientometric study, which included a look at the contributing authors, publications, contributing countries, top citation bursts, and topic categories. Based on the information obtained, in this research area, the publications started to increase dramatically since 2012. In terms of scientific output on oxide-based catalysts for water splitting, China and the United States were discovered to be the world leaders. [Display omitted] [ABSTRACT FROM AUTHOR]

• Novel oxygen permeable perovskite hollow fiber membrane with surface wrinkles was synthesised. • Sliver as a second phase catalyst could be anchored in the crevices of the wrinkles. • The wrinkled hollow fiber membranes are promising catalyst carrier. Oxygen permeable ceramic hollow fiber perovskite membranes could be applied as the micro-membrane reactors for high temperature oxidations to integrate air separation and reaction in same unit. Membrane reactors normally require the loading of extra catalyst. However, how to anchor the catalysts in these hollow fiber structured reactors along the surface is a big issue. In this work, the synthesis and properties of La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ (LSCF) hollow fiber perovskite membranes with wrinkled surface was reported. This article demonstrates its applicability for oxygen separation from air, before and after Ag deposition as the catalyst in the wrinkles of the hollow fibers. The wrinkled membranes display the oxygen permeation flux of 0.62 (prior to Ag deposition) and 1.48 (after Ag loading) mL·min−1·cm−2 operated at 950 °C, which is 1.2 and 3.0 times the permeation flux of membranes without wrinkles, respectively. This research contributes a novel inorganic hollow fiber membrane with wrinkled surfaces as the catalyst bed for industrial applications. [ABSTRACT FROM AUTHOR]

A dynamic model based on BaCe0.9Y0.1O3−δ (BCY10) perovskite membrane for steam permeation process is presented here to essentially investigate the internal mechanism. The transient concentration distribution and flux of the charged species and the electric potential distribution within the membrane on the steam permeation process are analyzed in detail via simulation based on this model. The results indicate that the flux of steam can be improved via elevating operating temperatures, enlarging the difference of the partial steam pressure between two sides of the membrane, increasing the membrane density, and reducing the membrane thickness. Moreover, it was found that the polarization electric potential between both sides of the membrane occurs during the steam permeation process, especially at the steady state of the steam permeation process. The polarization electric potential reaches the maximum value at about 1050 K in this membrane. The evolution of electric potential can explain the influence of the above-mentioned factors on the steam permeation process. This study advances the mechanism of steam permeation through perovskite membrane, which provides a new strategy for the fundamental investigation of related species permeation (oxygen, carbon dioxide, hydrogen, etc.) on inorganic membranes via transient modeling. [ABSTRACT FROM AUTHOR]

As a possible novel cost-effective method for oxygen production from air separation, ion-conducting ceramic membranes are becoming a hot research topic due to their potentials in clean energy and environmental processes. Oxygen separation via these ion-conducting membranes is completed via the bulk diffusion and surface reactions with a typical example of perovskite oxide membranes. To improve the membrane performance, silver (Ag) deposition on the membrane surface as the catalyst is a good strategy. However, the conventional silver coating method has the problem of particle aggregation, which severely lowers the catalytic efficiency. In this work, the perovskite oxide La0.8Ca0.2Fe0.94O3−a (LCF) and silver (5% by mole) composite (LCFA) as the membrane starting material was synthesized using one-pot method via the wet complexation where the metal and silver elements were sourced from their respective nitrate salts. LCFA hollow fiber membrane was prepared and comparatively investigated for air separation together with pure LCF hollow fiber membrane. Operated from 800 to 950 °C under sweep gas mode, the pure LCF membrane displayed the fluxes from 0.04 to 0.54 mL min−1 cm−2. Compared to pure LCF, under similar operating conditions, the flux of LCFA membrane was improved by 160%. [ABSTRACT FROM AUTHOR]

The merits of adjustable structure and composition and wide source of raw materials have convinced researchers to become more and more obsessed with the discussion of perovskite oxide materials and materials with perovskite structure in recent years. Perovskite type materials with excellent performance and well structural composition are expected to replace Pt/C, IrO 2 and RuO 2 , which are considered to be the most advanced active, valuable and cost-effective catalyst materials in the future. Therefore, finding catalysts with relatively higher economic and catalytic efficiency have always been the ideal goal of research for hydrogen production and O 2 /N 2 reduction. A large number of scholars have made significant efforts in developing various catalysts that remarkably enhance the catalytic activities of hydrogen evolution reaction (HER), oxygen evolution reaction (OER), oxygen reduction reaction (ORR), and nitrogen reduction reaction (NRR). This review aims to summarize some significant achievements in obtaining high-performance perovskite in the main related electro-catalysis field in recent years and provide a reference for the subsequent development of perovskite. This paper introduces the detailed methodology of the preparation of perovskite and discusses the design strategy of perovskite performance enhancement as important entry points to optimize the activity of perovskite. The paper comprehensively reviews the preparation methods of various perovskite with various examples, and also compares their advantages and disadvantages. To improve perovskite performance, most of the existing design strategies are introduced and integrated and novel design schemes are also displayed. The paper finally suggests the improvement potential in perovskite activity, aiming to create better design schemes of new perovskite in the future. • Conventional and new preparation methods of perovskite oxides catalysts are summarized. • Perovskites for hydrogen generation via hydrogen evolution reaction were summarized. • Perovskites for oxygen generation via oxygen evolution reaction were summarized. • Perovskites for nitrogen fixation via nitrogen reduction reaction were summarized. • Further performance improvement strategies of perovskite catalysts for electrochemistry are summarized. [ABSTRACT FROM AUTHOR]

Highlights • NO influence on oxygen permeation of perovskite membrane is probed. • The presence of NO would decrease the oxygen permeability below 900 °C. • The presence of NO can change the membrane surface. • NO influence can be avoided by lifting the operation temperature above 900 °C. Abstract Mixed conducting perovskite membrane has been intensively investigated as a possible new technology for oxygen production to replace the conventional cryogenic distillation which is capital and energy intensive. The perovskite membrane has the potential to be applied in the clean energy projects like oxy-fuel coal combustion if the membrane can withstand the real application conditions. Nitric oxide (NO) is an inevitable ingredient of flue gas from power plants, and it is important to understand the possible influence from NO on the perovskite membranes for producing pure oxygen for oxy-fuel project where the flue gas would be used as the sweep gas for the membrane operation. The influence of NO on the oxygen permeation properties of La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3−δ (LSCF) perovskite membrane is investigated by a variety of characterization techniques. The results indicate that the oxygen permeability of the LSCF membrane decreases significantly at the temperature below 900 °C. XRD, SEM and SEM-EDX characterizations indicate the generation of another porous phase damaging the membrane and accounting for the oxygen flux decrease. However, the negative effect from NO on the oxygen permeation would disappear when the temperature is elevated above 900 °C, on which NO would be decomposed to nitrogen and oxygen and no longer negatively influences the membrane. [ABSTRACT FROM AUTHOR]

BaCe 0.8 Y 0.2 O 3-δ proton conductor powder was prepared by sol-gel method, and the effects of sintering temperature and sintering aids addition on the mechanical properties and hydrogen permeability of BaCe 0.8 Y 0.2 O 3-δ proton conductor were investigated. XRD tests showed that when the addition of sintering aid Co 2 O 3 reached 5%, the BaCe 0.8 Y 0.2 O 3-δ proton conductor still showed a good perovskite phase. The sintering temperature of the sample with sintering aid is significantly lower than that of the blank sample. SEM shows that the addition of Co 2 O 3 , the proton conductor grains are closely arranged, the mechanical properties are increased, and the hydrogen permeability is significantly improved. • Co 2 O 3 was selected as an important sintering aid material. • The effect of sintering aid Co 2 O 3 on the mechanical properties of BCY was discussed. • The effect of sintering aid Co 2 O 3 on the hydrogen permeability of BCY was discussed. [ABSTRACT FROM AUTHOR]

• Annealing promotes to form more Co3+ and oxygen vacancies on the LaCoO 3-δ surface. • Triple-phase boundaries act as the active sites for electrocatalysis. • The nanoporous Ag-LaCoO 3-δ catalyst shows improved ORR performance. Substantial progress has been made in developing perovskite-based catalysts for oxygen reduction reaction (ORR). This article reported an ORR electrocatalyst composed of nanoporous Ag (NP-Ag) and LaCoO 3-δ (LC) perovskite oxide and designed to take advantage of the bi-continuous NP structure and high electrocatalytic performance of perovskite oxides. The triple-phase boundaries (TPBs) formed by NP-Ag and LC provided active sites for the electrocatalytic reactions. Further annealing promoted the interaction between NP-Ag and LC, which induced the formation of more Co3+ and surface oxygen vacancies, as proved by multiple characterizations. When the mass ratio of LC and NP-Ag was 1:2 (LC/Ag-1/2-A), the catalyst showed the best ORR performance with a relatively high half-wave potential, and only attenuated by 4% after 5,000 cycles of accelerated durability testing. Besides, it delivered significant bifunctionality towards both ORR and OER, bearing comparison with the reported perovskite-based electrocatalysts. This work demonstrated a novel route for extending the application of NP metals and facilely designing efficient bifunctional electrocatalysts. By mixing and annealing with nanoporous Ag, the charge transfer and surface chemical conditions of LaCoO 3-δ perovskite is modified to boost the ORR performance. [Display omitted] [ABSTRACT FROM AUTHOR]

Perovskite ceramic hollow fiber membranes (HFMs) have attracted great interest due to their potential application as the novel cost-effective method for oxygen production and favorable features for compact module preparation. However, the practical application of these perovskite HFMs is limited by the inherent brittleness of ceramic material and in cases of thick fiber wall, the insufficient oxygen flux values. In this work, highly asymmetric BaCo 0.85 Bi 0.05 Zr 0.1 O 3-δ (BCBZ) perovskite HFMs with a thin dense separation layer supported on the porous BCBZ substrate were fabricated by a modified phase inversion-sintering technique. The perovskite HFMs were integrated in a porous BCBZ perovskite matrix to form a bundle structure to simultaneously achieve high mechanical strength for membrane assembly and high O 2 permeation rate. Pure O 2 was achieved from air separation by vacuuming the permeate side of the hollow fiber bundles (HFBs). Oxygen recovery rate is a function of multi-factors including operation temperature, air feeding flow rate and the membrane area provided by the HFBs. The thermal cycle and post characterization results of the spent HFBs highlight the good stability of the fabricated HFBs. Oxygen permeation rate increased with the HFM number in the HFBs. Under static air atmosphere and the operation mode of vacuum application, the permeation rate of HFBs containing 3 HFMs (HFB_3) or 7 HFMs (HFB_7) at 1000 °C was 79.01 or 98.12 mL min−1, respectively. Normalized by the overall membrane area, the achieved oxygen flux for HFB_3 or HFB_7 was 13.27 or 7.06 mL cm−2 min−1, respectively, the difference of which is attributed to the limited air convection resulting in the insufficient oxygen supply in the feed once it is extracted. • BaCo 0.85 Bi 0.05 Zr 0.1 O 3-δ (BCBZ) perovskite and glue is used as the binder. • Highly asymmetric BCBZ hollow fiber (HF) possesses high O 2 flux. • BCBZ HF bundle further improves O 2 flux and mechanical property. • Bundling overcomes the weakness of the individual HFs. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract Perovskite oxides offer new opportunities in wastewater treatment via catalytic oxidation. Herein, we report a new application of perovskite oxides for biological detection via catalytic decolourisation and colorimetric determination. The presence of trace biomolecules in an aqueous system would interfere the decolourisation process of dyes, where the decolourisation rate is quantitatively correlated to the biomolecular concentration. In this work, trace L-cysteine (Cys) detection was demonstrated on the basis of a Ag-Ba 0.5 Sr 0.5 Co 0.75 Fe 0.2 O 3-δ (Ag-BSCF)/peroxymonosulfate/textile dye system. Thiol-containing cysteine can bind to Ag, Co and Fe atoms, therefore shielding the catalytic performance of the perovskite in degradation of dye solutions. Such a cost-effective biosensor system presents an excellent linear response in Cys concentration ranging from nM to μM. [ABSTRACT FROM AUTHOR]

Removal of toxic organics and bacterial disinfection are important tasks in wastewater treatment. Most heavy metal-based catalysts for degradation of aqueous organic pollutants in heterogeneous Fenton-like processes suffer from the toxicity of leached metals. The present work reports environmentally benign systems for both degradation of organics and bacterial disinfection. Calcium substituted LaFeO 3- δ perovskite was demonstrated as an efficient catalyst to activate peroxymonosulfate (PMS) for degradation of phenol, methylene blue and rhodamine 6 G. Compared to LaFeO 3- δ and nanocrystal Fe 3 O 4 , the lattice oxygen vacancies in B-site cation-deficient perovskite of La 0.8 Ca 0.2 Fe 0.94 O 3 - δ (LaCaFeO 3- δ ) particles renders this material a greatly improved catalytic performance. Electron paramagnetic resonance (EPR) suggested that both sulfate (SO 4 –) and hydroxyl radicals ( OH) played critical roles in the advanced oxidation processes. Moreover, silver doped perovskite (Ag-LaCaFeO 3- δ )/PMS successfully inhibited the growth of waterborne pathogen Escherichia coli and Methicillin-resistant Staphylococcus aureus (MRSA) at a lower dose than silver ions, proving a synergetic effect between free radicals and Ag + in killing the bacteria. Therefore, Ag-LaCaFeO 3- δ /PMS would be promising for practical wastewater treatment. [ABSTRACT FROM AUTHOR]

Negative impacts of wastewater contamination include harm to the environment, people, plants, and animals. Metal-based heterogeneous catalysts, particularly transition metal oxide catalysts, are a therapeutic option. However, they have limited reusability and cause secondary contaminations through metal leaching. In this work, a new membrane catalyst made of perovskite-type fiber was created and tested to remove methylene blue from wastewater. These innovative 3D perovskite ceramic catalysts work well in the breakdown of pollutants and dramatically lessen possible secondary contaminations caused by metal leaching from catalysts. [Display omitted] • La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ (LSCF) hollow fibre perovskite catalyst was developed. • It was evaluated for the removal of methylene blue via advanced oxidation. • It significantly reduces secondary contamination of metal leaching from perovskite. [ABSTRACT FROM AUTHOR]

Tonnage oxygen production is still mostly based on the traditional technology of cryogenic distillation, a century-old, capital- and energy-intensive method. It is critical to create a novel low-cost, energy-efficient approach that can meet the growing demand for oxygen in industry from the clean environmental or energy standpoint. Ruddlesden-Popper (RP) perovskite like oxides -based ionic transport membranes for the oxygen transport have recently been developed as a possible replacement for the traditional cryogenic approach. In this work, we detailly reviewed the progress of RP perovskite oxides based membranes for oxygen transport from separation mechanism, material types, synthesis methods to the final separation performance. This work advances the development of RP perovskite membranes for oxygen transport. [Display omitted] • MIEC oxides are the prominent materials for oxygen transport. • Oxygen conduction mechanism of MIEC oxides was discussed. • Preparation methods of MIEC oxide permeable materials were summarized. [ABSTRACT FROM AUTHOR]

The mixed ionic–electronic conducting (MIEC) oxides have generated significant research efforts in the scientific community during the last 40 years. Since then, many MIEC compounds, most of which are based on perovskite oxides, have been synthesized and characterized. These compounds, when heated to high temperatures, form solid ceramic membranes with high oxygen ionic and electrical conductivity. The driving force for oxygen ion transport is the ionic transfer of oxygen from the air as a result of the differential partial pressure of oxygen across the membrane. Electronic and ionic transport in a range of MIEC materials has been studied using the defect theory, particularly when dopants are introduced to the compound of interest. As a result, many types of ionic oxygen transport limits exist, each with a distinct phase shift depending on the temperature and partial pressure of oxygen in use. In combination with theoretical principles, this work attempts to evaluate the research community's major and meaningful achievements in this subject throughout the preceding four decades. [Display omitted] • MIEC oxides are the prominent materials for oxygen transport. • Oxygen conduction mechanism of MIEC oxides was discussed. • Preparation methods of MIEC oxide permeable materials were summarized. [ABSTRACT FROM AUTHOR]