Ferrite Perovskite Research Articles

0D/1D p-n heterostructured composite of bismuth ferrite perovskite clusters on sodium titanate nanotube arouse exceptional blue-light-driven photooxidation

This study describes the synthesis of a 0D/1D p-n heterostructured composite of bismuth ferrite perovskite clusters on sodium titanate nanotubes prepared using an in-situ hydrothermal method. BiFeO3/Na2Ti3O7 (BFT) nanocomposite, forming a p-n heterojunction due to the equilibrium of Fermi level, exhibits exceptional blue-light-driven photo-oxidation activity with an exceptional benzyl alcohol conversion rate of 29.64 mmolproduced BAD·g−1 h−1. The outstanding performance originates from the promotion of photogenerated charge separation and effective inhibition of charge recombination due to internal electric field of p-n heterojunction. Density functional theory calculations combined with femtosecond transient absorption spectroscopy distinctly confirms the efficient separation and transfer of photogenerated carriers to be S-scheme charge transfer mechanism over the p-n heterojunctions. Furthermore, in-situ infrared spectroscopy combined with XPS results demonstrate the strong adsorption of benzyl alcohol and weak adsorption of benzaldehyde on BFT, which facilitates the transformation of reactant and desorption of product. This study provides a simple and effective approach to enhance photocatalytic selective oxidation reactions.

EFFECT OF ANNEALING DURATION ON PHOTOCATALYTIC PROPERTIES OF LaFeO3 PEROVSKITE

In this paper, the effect of the annealing duration on the photocatalytic properties of lanthanum ferrite perovskite synthesized by the hydrothermal method is investigated. Lanthanum ferrite was chosen as the object of study due to its high activity under the influence of visible light. During the experiments, the structural changes occurring in the material during annealing during 2, 4 and 6 hours were studied. The main attention was paid to the analysis of the morphology of nanoparticles, phase composition, crystallinity, absorption spectra and photocatalytic activity. The results show that an increase in the annealing time leads to an improvement in the crystal structure, an increase in the size of crystallites and a higher level of oxygenation. The optimal annealing time to achieve maximum photocatalytic activity was determined to be 6 hours. The work confirms the prospects of using long-term annealing to improve the photocatalytic properties of perovskite-based materials.

Synthesis and Redox Properties of Iron and Iron Oxide Nanoparticles Obtained by Exsolution from Perovskite Ferrites Promoted by Auxiliary Reactions

Synthesis and Redox Properties of Iron and Iron Oxide Nanoparticles Obtained by Exsolution from Perovskite Ferrites Promoted by Auxiliary Reactions

Sonophotocatalytic degradation of sulfamethoxazole using lanthanum ferrite perovskite oxide anchored on an ultrasonically exfoliated porous graphitic carbon nitride nanosheet.

The lanthanum ferrite perovskite (La0.8FO) was synthesized using a citric combustion route and then modified with a porous graphitic nitride nanosheet via the wet impregnation-assisted ultrasonic method to produce La0.8FO@PgNS. Various techniques such as Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX) spectroscopy, X-ray photoelectron spectroscopy (XPS), ultraviolet diffuse reflectance spectroscopy (UV-DRS), and Tauc plot analysis were employed to confirm the functional moieties, crystallinity, phase change, morphology, composition, and bandgap of La.0.8FO and La0.8FO@PgNS. La0.8FO and La0.8FO@PgNS were used for the sonophotocatalytic oxidative degradation of sulfamethoxazole (SMX) under low energy and ultrasound wave frequency in the presence of visible light. La0.8FO and La0.8FO@PgNS exhibited a sonophotocatalytic degradation capacity of 52.06 and 99.60%, respectively. Furthermore, the rate constant at the optimum condition of pH 7 and 5 mg L-1 concentration was 0.01343 and 0.01494 min-1 for La0.8FO and La0.8FO@PgNS, respectively. The integration of sonolysis and photocatalysis in the remediation process of SMX resulted in a synergy of 2.5-fold. Ultrasonic waves and hydroxyl and superoxide radicals are the main species governing the degradation process while La0.8FO@PgNS was stable over 8 cycles, proving to be a sustainable material for environmental remediation.

Unusual Lattice Dilation and Strong Electron–Phonon Coupling in Erbium Ferrite Perovskite

Unusual Lattice Dilation and Strong Electron–Phonon Coupling in Erbium Ferrite Perovskite

Tailoring the A and B site of Fe-based perovskites for high selectivity in the reverse water-gas shift reaction

The reverse water-gas shift reaction (rWGS) is of particular interest as it is the first step to producing high-added-value products from carbon dioxide (CO2) and renewable hydrogen (H2), such as synthetic fuels or other chemical building blocks (e.g. methanol) through a modified Fischer-Tropsch process. However, side reactions and material deactivation issues, depending on the conditions used, still make it challenging. Efforts have been put into developing and improving scalable catalysts that can deliver high selectivity while at the same time being able to avoid deactivation through high temperature sintering and/or carbon deposition. Here we design a set of perovskite ferrites specifically tailored to the hydrogenation of CO2 via the reverse water-gas shift reaction. We tailor the oxygen vacancies, proven to play a major role in the process, by partially substituting the primary A-site element (Barium, Ba) with Praseodymium (Pr) and Samarium (Sm), and also dope the B-site with a small amount of Nickel (Ni). We also take advantage of the exsolution process and manage to produce highly selective Fe-Ni alloys that suppress the formation of any by-products, leading to up to 100% CO selectivity.

Unlocking the Potential of Bismuth‐Based Materials in Supercapacitor Technology: A Comprehensive Review

AbstractSupercapacitors (SCs) have attracted significant attention in the realm of energy storage devices due to their exceptional features, such as enhanced charge storage capacity, fast charge‐discharge rates, and high power density. The emergence of cost‐effective and highly productive SCs is a topic of interest among industrial and scientific communities. Ferrites with a perovskite crystal structure are often considered excellent electrode materials due to their intrinsic properties, affordability, low environmental impact, and widespread availability. An in‐depth investigation of perovskite ferrites in the context of SCs is necessary to advance the understanding of these materials. The techniques used in the synthesis of ABO3‐type perovskite bismuth ferrite materials are comprehensively reviewed in this review. The review starts by analyzing various types of SCs classified based on their electrode materials. The review provides a comprehensive understanding of the design and functionality of these devices, serving as an important source of inspiration for new methods of synthesis and fabrication methodologies that aim to produce environmentally friendly SCs.

Rational Design of Ruddlesden–Popper Perovskite Ferrites as Air Electrode for Highly Active and Durable Reversible Protonic Ceramic Cells

HighlightsA novel A/B-sites co-substitution strategy was introduced to enhance the performance and durability of Ruddlesden–Popper perovskite Sr3Fe2O7−δ (SF)-based air electrodes for reversible protonic ceramic cells (RePCCs).Simultaneous Sr-deficiency and Nb-substitution in SF result in Sr2.8Fe1.8Nb0.2O7−δ (D-SFN), offering improved structural stability under RePCC conditions by suppressing the formation of Sr3Fe2(OH)12 phase.The introduction of Sr-deficiency enhances oxygen vacancy concentration in D-SFN, promoting efficient oxygen transport within the material and contributing to excellent activity in RePCCs.

Enhancing layered perovskite ferrites with ultra-high-density nanoparticles via cobalt doping for ceramic fuel cell anode

Nanoparticles anchored on the perovskite surface have gained considerable attention for their wide-ranging applications in heterogeneous catalysis and energy conversion due to their robust and integrated structural configuration. Herein, we employ controlled Co doping to effectively enhance the nanoparticle exsolution process in layered perovskite ferrites materials. CoFe alloy nanoparticles with ultra-high-density are exsolved on the (PrBa)0.95(Fe0.8Co0.1Nb0.1)2O5+δ (PBFCN0.1) surface under reducing atmosphere, providing significant amounts of reaction sites and good durability for hydrocarbon catalysis. Under a reducing atmosphere, cobalt facilitates the reduction of iron cations within PBFCN0.1, leading to the formation of CoFe alloy nanoparticles. This formation is accompanied by a cation exchange process, wherein, with the increase in temperature, partial cobalt ions are substituted by iron. Meanwhile, Co doping significantly enhance the electrical conductivity due to the stronger covalency of the CoO bond compared with FeO bond. A single cell with the configuration of PBFCN0.1-Sm0.2Ce0.8O1.9 (SDC)|SDC|Ba0.5Sr0.5Co0.8Fe0.2O3−δ (BSCF)-SDC achieves an extremely low polarization resistance of 0.0163 Ω cm2 and a high peak power density of 740 mW cm−2 at 800 °C. The cell also shows stable operation for 120 h in H2 with a constant current density of 285 mA cm−2. Furthermore, employing wet C2H6 as fuel, the cell demonstrates remarkable performance, achieving peak power densities of 455 mW cm−2 at 800 °C and 320 mW cm−2 at 750 °C, marking improvements of 36% and 70% over the cell with (PrBa)0.95(Fe0.9Nb0.1)2O5+δ (PBFN)-SDC at these respective temperatures. This discovery emphasizes how temperature influences alloy nanoparticles exsolution within doped layered perovskite ferrites materials, paving the way for the development of high-performance ceramic fuel cell anodes.

Bismuth-doped lanthanum ferrite perovskites: A promising approach for enhancing photo-Fenton degradation of organic dye pollutants

Fabrication of efficient perovskite photo-Fenton catalytic systems is recognized as an effective strategy for clean water production. However, modifying perovskite catalysts effectively remains a formidable challenge. In this study, we prepared Bi-doped LaFeO3 photo-Fenton catalysts using a facile microwave-assisted method. Various characterization techniques confirmed the successful formation of these Bi-doped LaFeO3 perovskite materials. The photo-Fenton activity of the Bi-doped LaFeO3 perovskite materials with varying Bi content was assessed by monitoring the degradation of methylene blue (MB) dye solution. Remarkably, the optimized Bi-doped LaFeO3 (referred to as LBFO3) catalyst achieved approximately 93.64% degradation of MB within 100 min of visible light exposure, demonstrating exceptional efficacy in treating wastewater containing organic dye pollutants. The enhanced photocatalytic activity of the LBFO3 perovskite materials arises from the incorporation of Bi, leading to an expanded optical absorption range, increased specific surface area, and enhanced separation and migration of photo-generated carriers. Importantly, the LBFO3 photo-Fenton system exhibited remarkable stability during four successive cycling treatments, indicating promising practical applications. Additionally, quenching experiments were conducted to elucidate electron transfer in the LBFO3 catalyst related to the photo-Fenton degradation mechanism of MB. This study might pave the way toward designing novel perovskite based photo-Fenton systems for highly efficient degradation of waterborne contaminants.

All oxide lead-free bismuth ferrite perovskite absorber based FTO/ZnO/BiFeO3/Au solar cell with efficiency ∼ 12%: First principle material and macroscopic device simulation studies

We report the photovoltaic response of bismuth ferrite (BiFeO3) multiferroic absorber based all oxide FTO/ZnO/BiFeO3/Au solar cell using density functional theory for materials optoelectronic properties and macroscopic device simulation-based hybrid approach. The structural, electronic, and optical properties of BiFeO3 are investigated using density functional theory (DFT). The band structure and density of states of R3c-BiFeO3 are computed considering the Hubbard parameter Ueff∼4.2eV for both Fe-3d and O-2p orbitals for matching the experimental bandgap of ∼2.5eV. The computed optical properties, such as absorption for rhombohedral R3c-BiFeO3, are used to investigate FTO/ZnO/BiFeO3/Au solar cell performance using a macroscopic device simulation approach. The thickness, acceptor concentration, defect concentration of the absorber layer, interface defect density, electron affinity of the electron transport layer, and the impact of series, shunt resistance, and metal back contact are investigated to optimize the photovoltaic response under realistic conditions. The optimum photoconversion efficiency (PCE) is ∼11.92% with open circuit voltage (Voc) of 1.033V, short circuit current density (Jsc) of 15.27mA/cm2, and fill factor (FF) of 75.59%. This study on BiFeO3-based absorber materials opens a way to realize lead-free perovskite absorber material with a potential for realizing all oxide solar cells.

Clean and Sustainable Power to X to Power by Reversible Symmetrical Solid Oxide Cells with Highly Active Ferrite Perovskite Electrodes

Clean and Sustainable Power to X to Power by Reversible Symmetrical Solid Oxide Cells with Highly Active Ferrite Perovskite Electrodes

Molecular analog of perovskite ferrites: First-principles studies of electronic and magnetic properties

Molecular analog of perovskite ferrites: First-principles studies of electronic and magnetic properties

Cation ordered doping of ferrite perovskites: influence on redox behaviour, magnetism and mixed ionic electronic conductivity

Cation ordered doping of ferrite perovskites: influence on redox behaviour, magnetism and mixed ionic electronic conductivity

Analysis of structural and optical properties in co doped Mn,Gd in bismuth ferrite (BiFeO3) thin films prepared by sol-gel technique

In this paper, we reported the structural and optical properties of co-doped bismuth ferrite (Bi0.99Gd0.01Fe0.99Mn0.01 O3) thin films that were fabricated on corning glass substrates by sol-gel spin coating technique. The thin films were deposited in different layers on the glass substrates(3,4,5-layers) and annealed at 550 °C in a muffle furnace for 2 hrs in air. The effect of co-doping and thickness on structural and optical properties of bismuth ferrite perovskite thin film was systematically studied and analyzed. The X-ray diffraction pattern of the sample films fabricated confirms the existence of a Rhombohedral structure with space group (RE). Transmittance spectra and absorption spectra were determined by Ultraviolet–visible (UV–Vis) spectrophotometer. The optical band gap of films with different coating layers was estimated from Tauc’s plot of the optical data.

Kinetic and Thermodynamic Enhancement of Low-Temperature Oxygen Release from Strontium Ferrite Perovskites Modified with Ag and CeO2.

The redox behavior of the nonstoichiometric perovskite oxide SrFeO3-δ modified with Ag, CeO2, and Ce was assessed for chemical looping air separation (CLAS) via thermogravimetric analysis and by cyclic release and uptake of O2 in a packed bed reactor. The results demonstrated that the addition of ∼15 wt % Ag at the surface of SrFeO3-δ lowers the temperature of oxygen release in N2 by ∼60 °C (i.e., from 370 °C for bare SrFeO3-δ to 310 °C) and more than triples the amount of oxygen released per CLAS cycle at 500 °C. Impregnation of SrFeO3-δ with Ag increased the concentration of oxygen vacancies at equilibrium, lowering (3 - δ) under all investigated oxygen partial pressures. The addition of CeO2 at the surface or into the bulk of SrFeO3-δ resulted in more modest changes, with a decrease in temperature for O2 release of 20-25 °C as compared to SrFeO3-δ and a moderate increase in oxygen yield per reduction cycle. The apparent kinetic parameters for reduction of SrFeO3-δ, with Ag and CeO2 additives, were determined from the CLAS experiments in a packed bed reactor, giving activation energies and pre-exponential factors of Ea,reduction = 66.3 kJ mol-1 and Areduction = 152 mol s-1 m-3 Pa-1 for SrFeO3-δ impregnated with 10.7 wt % CeO2, 75.7 kJ mol-1 and 623 molO2 s-1 m -3 Pa-1 for SrFeO3-δ mixed with 2.5 wt % CeO2 in the bulk, 29.9 kJ mol-1 and 0.88 molO2 s-1 m-3 Pa-1 for Sr0.95Ce0.05FeO3-δ, and 69.0 kJ mol-1 and 278 molO2 s-1 m-3 Pa-1 for SrFeO3-δ impregnated with 12.7 wt % Ag, respectively. Kinetics for reoxidation were much faster and were assessed for two materials with the slowest oxygen uptake, SrFeO3-δ, giving the activation energy Ea,oxidation = 177.1 kJ mol-1 and pre-exponential factor Aoxidation = 3.40 × 1010 molO2 s-1 m-3 Pa-1, and Sr0.95Ce0.05FeO3-δ, giving the activation energy Ea,oxidation = 64.0 kJ mol-1, and pre-exponential factor Aoxidation = 584 molO2 s-1 m-3 Pa-1.

Dynamic tracking of exsolved PdPt alloy/perovskite catalyst for efficient lean methane oxidation

Supported Pd based catalysts are considered as the efficient candidates for low-carbon alkane oxidation for their outstanding capability to break C-H bond. Whereas, the irreversible deactivation of Pd based catalysts was still frequently observed. Herein, we reinforced the extruded Pd nanoparticles with quantitive Pt to assemble the evenly distributed PdPt nanoalloy onto ferrite perovskite (PdPt-LCF) matrix with strengthened robustness of metal/oxide support interface. We further co-achieved the enhanced performance, anti-overoxidation as well as resistance of vapor-poisoning in durability measurement. The operando X-ray photoelectron spectroscopy (O-XPS) combined with various morphology characterizations confirms that the accumulation of surface deep-oxidation species of Pd4+ is the culprit for fast activity loss in exsolved Pd system, especially at high temperature of 400 °C. Conversely, it could be completely suppressed by in-situ alloying Pd with equal amount of Pt, which helps maintain the metastable Pd2+/Pd shell and metallic solid-solution core structure. The density function theory (DFT) calculations further buttress that the dissociation of CH was facilitated on alloy/perovskite interface which is, on the contrary, resistant toward O–H bond cleavage, as compared to Pd/perovskite. Our work suggests that the modification of exsolved metal/oxide catalytic interface could further enrich the toolkit of heterogeneous catalyst design.

Green synthesis of ammonia from steam and air using solid oxide electrolysis cells composed of ruthenium‐modified perovskite catalyst

AbstractThe green electrochemical synthesis of ammonia (NH3) through solid electrolysis has been intensively investigated. This research reported an improvement of NH3 production rate using in situ exsolution of ruthenium (Ru) atoms into lanthanum strontium chromium ferrite perovskite (LaxSr1−xCryFe1−yO3−δ) catalyst. The in situ Ru exsolution was achieved by reducing the optimized stoichiometric La0.33Sr0.67Cr0.33Fe0.52Ru0.15O3−δ (LSCrFRu) powders obtained in 10‐vol% H2/Ar at 800°C for 1.0 h. These Ru nanoparticles (NPs) were embedded on the surface of the LSCrFRu matrix, evenly distributed with a size varying from 4.4 ± 0.5 nm. With the exsolution of Ru atoms, greater oxygen vacancies were formed in ex‐LSCrFRu and gadolinium‐doped ceria (GDC) composite than those in LSCrF‐GDC electrocatalyst, beneficial to N2 gas adsorption and triple bond cleavage. These Ru‐modified LSCrFRu‐GDC catalysts showed a synthesis rate of 4.73 × 10−10 mol s−1 cm−2 at 550°C under 1.6 V, doubling the rate using LSCrF‐GDC catalyst. The improved ammonia synthesis kinetic is mainly attributed to embedded Ru NPs and the increased oxygen vacancies formed during the in situ exsolution process. More active sites and higher activity for H2O and N2 adsorption and activation collectively advanced facile transportation of O2− that further promotes the cleavage of covalent bonds in H2O, providing more H+ for the hydrogenation in the nitrogen reduction reaction. This research will open a new paradigm for the electrochemical synthesis of ammonia with mitigating the drawbacks of traditional NH3 production.

Sub PPM Detection of NO2 Using Strontium Doped Bismuth Ferrite Nanostructures.

The present work investigates the NO2 sensing properties of acceptor-doped ferrite perovskite nanostructures. The Sr-doped BiFeO3 nanostructures were synthesized by a salt precursor-based modified pechini method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). The synthesized materials were drop coated to fabricate chemoresistive gas sensors, delivering a maximum sensitivity of 5.2 towards 2 ppm NO2 at 260 °C. The recorded values of response and recovery time are 95 s and 280 s, respectively. The sensor based on Bi0.8Sr0.2FeO3-δ (BSFO) that was operated was shown to have a LOD (limit of detection) as low as 200 ppb. The sensor proved to be promising for repeatability and selectivity measurements, indicating that the Sr doping Bismuth ferrite could be a potentially competitive material for sensing applications. A relevant gas-sensing mechanism is also proposed based on the surface adsorption and reaction behavior of the material.

Palladium exsolution and dissolution with lanthanum ferrite perovskite oxides

Palladium exsolution and dissolution with lanthanum ferrite perovskite oxides