Search Results (863)

Currently, the trade-off between oxygen permeation flux and structural stability in conventional perovskite oxides restricts the practical application of oxygen permeable membranes. In this study, a high-entropy design was applied to the B-site of BSCF matrix materials, resulting in the successful synthesis of a high-entropy perovskite, Ba_0.5Sr_0.5Co_0.71Fe_0.2Ta_0.03Ni_0.03Zr_0.03O_3−δ. The crystal structure, microstructure, and elemental composition of the material were systematically characterized and analyzed. Theoretical analysis and experimental characterization confirm that the material exhibits a stable single-phase high-entropy perovskite oxide structure. Under He as the sweep gas, the membrane achieved an oxygen permeation flux of 1.28 mL·cm⁻²·min⁻¹ and operated stably for over 100 h (1 mm thick, 900 °C). In a 20% CO₂/He atmosphere, the flux remained above 0.92 mL·cm⁻²·min⁻¹ for over 100 h, demonstrating good CO₂ tolerance. Notably, when the sweep gas is returned to the pure He atmosphere, the oxygen permeation flux fully recovers to 1.28 mL·cm⁻²·min⁻¹, with no evidence of leakage. These findings indicate that the proposed B-site doping strategy can break the trade-off between oxygen permeability and structural stability in conventional perovskite membranes. This advancement supports the industrialization of oxygen permeable membranes and offers valuable theoretical guidance for the design of high-performance perovskite materials. Full article

The commercialization of proton-conducting fuel cells (PCFCs) is hindered by the limited electroactivity and durability of cathodes at intermediate temperatures ranging from 400 to 700 °C, a challenge exacerbated by an insufficient understanding of high-entropy perovskite (HEP) materials for oxygen reduction reaction (ORR) optimization. This study introduces an yttrium-doped HEP to address these limitations. A comparative analysis of Ce_0.2−xY_xBa_0.2Sr_0.2La_0.2Ca_0.2CoO_3−δ (x = 0, 0.2; designated as CBSLCC and YBSLCC) revealed that yttrium doping enhanced the ORR activity, reduced the thermal expansion coefficient (19.9 × 10⁻⁶ K⁻¹, 30–900 °C), and improved the thermomechanical compatibility with the BaZr_0.1Ce_0.7Y_0.1Yb_0.1O_3−δ electrolytes. Electrochemical testing demonstrated a peak power density equal to 586 mW cm⁻² at 700 °C, with a polarization resistance equaling 0.3 Ω cm². Yttrium-induced lattice distortion promotes proton adsorption while suppressing detrimental Co spin-state transitions. These findings advance the development of durable, high-efficiency PCFC cathodes, offering immediate applications in clean energy systems, particularly for distributed power generation. Full article

Novel high-entropy perovskite oxide powders were synthesized using a sol-gel process. The B-site contained five cations: chromium, cobalt, iron, manganese, and nickel. The B-site cations were present on an equiatomic basis. The A-site cation was lanthanum, with calcium doping. The amount of A-site doping varied from 0 to 30 at%, yielding a composition of La_1−xCa_x(Co_0.2Cr_0.2Fe_0.2Mn_0.2Ni_0.2)O_3−δ. The resulting perovskite powders were pressurelessly sintered in air at 1400 °C for 2 h. Sintered densities were measured, and the grain structure was imaged via scanning electron microscopy to investigate the effect of doping. Samples were cut and polished, and their resistance was measured at varying temperatures in air to obtain the electrical conductivity and the mechanism that governs it. Plots of electrical conductivity as a function of composition and temperature indicate that the increased configurational entropy of the perovskite materials has a demonstrable effect. Full article

In this study, Sr_0.95Bi_0.05TiO₃ was synthesized via solid state reaction, characterized, and applied as a visible-light-active photocatalyst for the degradation of oxytetracycline, imidacloprid, and their mixture. To evaluate the influence of the aqueous matrix on pollutant degradation, photocatalytic experiments were carried out in both distilled water and a real environmental sample (surface water). The Sr_0.95Bi_0.05TiO₃ perovskite showed high photocatalytic performance under visible light, achieving nearly complete degradation of oxytetracycline after 2 h, and significant removal of imidacloprid in river water (60% after 3 h). Enhanced degradation in surface water was attributed to favorable ionic composition and pH. The perovskite oxide maintained its photocatalytic performance over five consecutive cycles, with no significant loss in photocatalytic activity or structural and morphological stability. Ecotoxicological assessment using Daphnia magna confirmed that the treated water was non-toxic, indicating that no harmful byproducts were formed. Complementary Density Functional Theory calculations were conducted to complement experimental findings, providing insights into the structural, electronic, and optical properties of the photocatalyst, enhancing the understanding of the degradation mechanisms involved. This integrated approach, combining experimental photocatalytic performance evaluation in different matrices, ecotoxicity testing, and theoretical modeling, highlights Sr_0.95Bi_0.05TiO₃ as a promising, stable, and environmentally safe photocatalyst for practical wastewater treatment applications. Full article

Recently, we have described SrMo_1-xMg_xO_3-δ perovskites (x = 0.1, 0.2) as excellent anode materials for solid oxide fuel cells (SOFCs), with mixed ionic and electronic conduction (MIEC) properties. After depositing on the solid electrolyte, they were annealed for sintering at high temperatures (typically 1000 °C), giving rise to oxidized scheelite-type phases, with SrMo_1-xMg_xO_4-δ (x = 0.1, 0.2) stoichiometry. To obtain the active perovskite phases, they were reduced again in the working anode conditions, under H₂ atmosphere. Therefore, there must be an excellent reversibility between the oxidized Sr(Mo, Mg)O_4-δ scheelite and the reduced Sr(Mo, Mg)O_3-δ perovskite phases. This work describes the topotactical oxidation, by annealing at 400 °C in air, of the SrMo_0.9Mg_0.1O_3-δ perovskite oxide. The characterization by X-ray diffraction (XRD) and neutron powder diffraction (NPD) was carried out in order to determine the crystal structure features. The scheelite oxides are tetragonal, space group I4₁/a (No. 88), whereas the perovskites are cubic, s.g. Pm-3m (No. 221). The Rietveld refinement of the scheelite phase from NPD data after annealing the perovskite at 400 °C and cooling it down slowly to RT evidences the absence of intermediate phases between perovskite and scheelite oxides, as well as the presence of oxygen vacancies in both oxidized and reduced phases, essential for their performance as MIEC oxides. The topotactical relationship between both crystal structures is discussed. Full article

Lanthanide perovskite materials are promising candidates for supercapacitor applications. In this study, a series of La_1−xCa_xCrO₃ (x = 0–0.2) materials were prepared by sol-gel method, incorporating bivalent ions calcium at A-site. La_0.85Ca_0.15CrO₃ exhibited the lowest charge transfer resistance and highest specific surface area. At 1 A/g, La_0.85Ca_0.15CrO₃ achieved a maximum specific capacitance of 306 F/g, about 2.3 times higher than that of the LaCrO₃ (133 F/g). Based on the observed data, a mechanism involving oxygen anion charge storage during the charging-discharging process is proposed. After 5000 long cycle, the coulomb efficiency of the electrode remains above 94%. These results demonstrate that Ca-substituted compounds exhibit significant potential for A-site engineering in supercapacitor applications. Full article

Perovskite bionic eyes have emerged as highly promising candidates for photodetection applications to their wide-angle imaging capabilities, high external quantum efficiency(EQE), and low-cost fabrication and integration. Since their initial exploration in 2015, significant advancements have been achieved in this field, with their EQE reaching 27%. Nevertheless, intrinsic challenges such as the oxidation susceptibility of perovskites and difficulties in curved surface growth hinder their further development. Addressing these issues necessitates a comprehensive and systematic understanding of the preparation mechanisms for hemispherical perovskite, as well as the development of effective mitigation strategies. In this review, a review published provides a detailed overview of the research progress in hemispherical perovskite photodetectors, with a particular focus on the fundamental properties and fabrication pathways of hemispherical perovskites. Furthermore, various strategies to enhance the performance of hemispherical perovskite and overcome preparation challenges are thoroughly discussed. Finally, existing challenges and perspectives are presented to further advance the development of eco-friendly hemispherical perovskite. Full article

This work explored an electrochemical approach for synthesizing lanthanum-modified nickel oxide (NiO_x:La) as a hole transport layer (HTL) in inverted perovskite solar cells (IPSCs). By varying the La³⁺ concentration, the chemical, charge transport, structural, and morphological properties of the NiO_x:La film and the HTL/PVK interface were evaluated to enhance photovoltaic performance. X-ray photoelectron spectroscopy (XPS) confirmed La³⁺ incorporation, a higher Ni³⁺/Ni³⁺ ratio, and a valence band shift, improving p-type conductivity. Electrochemical impedance spectroscopy and Mott–Schottky analyses indicated that NiO_x:La 0.5% exhibited the lowest resistance and the highest carrier density, correlating with higher recombination resistance. The NiO_x:La 0.5% based cell achieved a PCE of 20.08%. XRD and SEM confirmed no significant changes in PVK structure, while photoluminescence extinction demonstrated improved charge extraction. After 50 days, this cell retained 80% of its initial PCE, whereas a pristine NiO_x device retained 75%. Hyperspectral imaging revealed lower optical absorption loss and better homogeneity. These results highlight NiO_x:La as a promising HTL for efficient and stable IPSCs. Full article

The structural and electrical properties of double perovskite compounds SrLaFe_1−xMn_xTiO_6−δ (x = 0, 0.33, 0.67, and 1.0) were studied using X-ray diffraction (XRD) and dielectric impedance measurements. The reparation of perovskite compounds was successfully achieved through the precursor solid-state reaction in air at 1250 °C. The purity phase and crystal structures of perovskite compounds were determined by means of the standard Rietveld refinement method using the FullProf suite. The best fitting results showed that SrLaFeTiO_6−δ was orthorhombic with space group Pnma, and both SrLaFe_0.67Mn_0.33TiO_6−δ and SrLaFe_0.33Mn_0.67TiO_6−δ were cubic structures with space group Fm3m, while SrLaMnTiO_6−δ was tetragonal with a I/4m space group. The charge density maps obtained for these structures indicated that the compounds show an ionic and mixed ionic–electronic conduction. The dielectric impedance measurements were carried out in the range of 20 Hz to 1 MHz, and the analysis showed that there is more than one relaxation mechanism of Debye type. Doping with Mn was found to reduce the dielectric impedance of the samples, and the major contribution to the dielectric impedance was established to change from a capacitive for SrLaFeTiO_6−δ to a resistive for SrLaMnTiO_6−δ. The fall in values of electrical resistance may be related to the possible occurrence of the double exchange (DEX) mechanism among the Mn ions, provided there is oxygen deficiency in the samples. DC-resistivity measurements revealed that SrLaFeTiO_6−δ was an insulator while SrLaMnTiO_6−δ was showing a semiconductor–metallic transition at ~250 K, which is in support of the DEX interaction. The dielectric impedance of SrLaFe_0.67Mn_0.33TiO_6−δ was found to be similar to that of (La,Sr)(Co,Fe)O_3-δ, the mixed ionic–electronic conductor (MIEC) model. The occurrence of a mixed ionic–electronic state in these compounds may qualify them to be used in free lead solar cells and energy storage technology. Full article

Due to the increase in energy demand, photocatalytic hydrogen (H₂) production has received enormous interest from the scientific community due to its simplicity and cost-effectiveness. The photocatalyst (PC) plays a vital role in H₂ evolution, and it is well understood that an efficient PC should have a larger surface area and better charge separation and transport properties. Previously, extensive efforts were made to prepare the efficient PC for photocatalytic H₂ production. In some cases, pristine catalyst could not catalyze the catalytic reactions due to a fast recombination rate or poor catalytic behavior. Thus, cocatalysts can be explored to boost the photocatalytic H₂ production. In this regard, a promising cocatalyst should have a large surface area, more active sites, decent conductivity, and improved catalytic properties. Molybdenum disulfide (MoS₂) is one of the two-dimensional (2D) layered materials that have excellent optical, electrical, and physicochemical properties. MoS₂ has been widely utilized as a cocatalyst for the photocatalytic H₂ evolution under visible light. Herein, we have reviewed the progress in the fabrication of MoS₂ and its composites with metal oxides, perovskite, graphene, carbon nanotubes, graphitic carbon nitrides, polymers, MXenes, metal-organic frameworks, layered double hydroxides, metal sulfides, etc. for photocatalytic H₂ evolution. The reports showed that MoS₂ is one of the desirable cocatalysts for photocatalytic H₂ production applications. The challenges and future perspectives are also mentioned. This study may be beneficial for the researchers working on the design and fabrication of MoS₂-based PCs for photocatalytic H₂ evolution applications. Full article

Understanding strain behavior near grain boundaries is critical for controlling structural distortions and oxygen vacancy migration in perovskite oxides. However, conventional techniques often lack the spatial resolution needed to analyze phase and domain evolution at the nanoscale. In this paper, polarization-dependent second-harmonic generation (SHG) imaging is employed as a tool to probe local symmetry breaking and complex domain structures in the vicinity of a low-angle grain boundary of SrTiO₃ (STO) bicrystals. We show that the anisotropic strain introduced by a tilted grain boundary produces strong local distortions, leading to the coexistence of tetragonal and rhombohedral domains. By analyzing SHG intensity and variations in the second-order nonlinear optical susceptibility, we map the distribution of strain fields and domain configurations near the boundary. In pristine samples, the grain boundary acts as a localized source of strain accumulation and symmetry breaking, while in samples subjected to intentional electrical stressing, the SHG response becomes broader and more uniform, suggesting strain relaxation. This work highlights SHG imaging as a powerful technique for visualizing grain-boundary-driven structural changes, with broad implications for the design of strain-engineered functional oxide devices. Full article

In recent years, inverted perovskite solar cells (PSCs) have garnered widespread attention due to their high compatibility, excellent stability, and potential for low-temperature manufacturing. However, most of the current research has primarily focused on the surface passivation of perovskite. In contrast, the buried interface significantly influences the crystal growth quality of perovskite, but it is difficult to effectively control, leading to relatively slow research progress. To address the issue of poor interfacial contact between the hole transport-layer nickel oxide (NiOX) and the perovskite, we introduced a conjugated self-assembled monolayer (SAM), 4,4′-[(4-(3,6-dimethoxy-9H-carbazole)triphenylamine)]diphenylacetic acid (XS21), which features triphenylamine dicarboxylate groups. For comparison, we also employed the widely studied phosphonic acid-based SAM, [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl] phosphonic acid (MeO-2PACz). A systematic investigation was carried out to evaluate the influence of these SAMs on the performance and stability of inverted PSCs. The results show that both XS21 and MeO-2PACz significantly enhanced the crystallinity of the perovskite layer, reduced defect densities, and suppressed non-radiative recombination. These improvements led to more efficient hole extraction and transport at the buried interface. Consequently, inverted PSCs incorporating XS21 and MeO-2PACz achieved impressive power-conversion efficiencies (PCEs) of 21.43% and 22.43%, respectively, along with marked enhancements in operational stability. Full article

Two-dimensional film materials with unique atomic structures and electronic operation modes have demonstrated amazing application potential and value in the field of high technology. Among the various methods for preparing 2D film materials, PLD technology has become the preferred technology for rapid and green preparation of high-quality, complex structured 2D film materials due to its features such as maintaining the excellent stoichiometric ratio of the target, strong process flexibility, and non-polluting environment. Therefore, this paper discusses the exciting topic of PLD technology in the preparation and application of 2D film materials. Based on a systematic exposition of its basic principles and influencing factors, it provides a detailed overview of the current application status of PLD technology in the preparation of various 2D film materials such as carbides, sulfides, oxides, nitrides, and perovskites. Meanwhile, the advantages and disadvantages of PLD technology in the preparation of 2D film materials were also positively summarized, and the challenges and emerging strategies it faces in the future preparation of 2D film materials were cautiously discussed. This provides practical suggestions and reflections for the sustainable development of PLD technology in the fields of basic research, performance regulation, device development, and application of 2D film materials preparation. Full article

Solid oxide fuel cells (SOFCs) represent a pivotal technology in renewable energy due to their clean and efficient power generation capabilities. Their role in potential carbon mitigation enhances their viability. SOFCs can operate via a variety of alternative fuels, including hydrocarbons, alcohols, solid carbon, and ammonia. However, several solutions have been proposed to overcome various technical issues and to allow for stable operation in dry methane, without coking in the anode layer. To avoid coke formation thermodynamically, methane is typically reformed, contributing to an increased degradation rate through the addition of oxygen-containing gases into the fuel gas to increase the O/C ratio. The performance achieved by reforming catalytic materials, comprising active sites, supports, and electrochemical testing, significantly influences catalyst performance, showing relatively high open-circuit voltages and coking-resistance of the CH₄ reforming catalysts. In the next step, the operating principles and thermodynamics of methane reforming are explored, including their traditional catalyst materials and their accompanying challenges. This work explores the components and functions of SOFCs, particularly focusing on anode materials such as perovskites, Ruddlesden–Popper oxides, and spinels, along with their structure–property relationships, including their ionic and electronic conductivity, thermal expansion coefficients, and acidity/basicity. Mechanistic and kinetic studies of common reforming processes, including steam reforming, partial oxidation, CO₂ reforming, and the mixed steam and dry reforming of methane, are analyzed. Furthermore, this review examines catalyst deactivation mechanisms, specifically carbon and metal sulfide formation, and the performance of methane reforming and partial oxidation catalysts in SOFCs. Single-cell performance, including that of various perovskite and related oxides, activity/stability enhancement by infiltration, and the simulation and modeling of electrochemical performance, is discussed. This review also addresses research challenges in regards to methane reforming and partial oxidation within SOFCs, such as gas composition changes and large thermal gradients in stack systems. Finally, this review investigates the modeling of catalytic and non-catalytic processes using different dimension and segment simulations of steam methane reforming, presenting new engineering designs, material developments, and the latest knowledge to guide the development of and the driving force behind an oxygen concentration gradient through the external circuit to the cathode. Full article

Artificial photoelectric synapses exhibit great potential for overcoming the Von Neumann bottleneck in computational systems. All-inorganic halide perovskites hold considerable promise in photoelectric synapses due to their superior photon-harvesting efficiency. In this study, a novel wavy-structured CsPbBr₃/ZnO hybrid film was realized by depositing zinc oxide (ZnO) onto island-like CsPbBr₃ film via atomic layer deposition (ALD) at 70 °C. Due to the capability of ALD to grow high-quality films over small surface areas, dense and thin ZnO film filled the gaps between the island-shaped CsPbBr₃ grains, thereby enabling reduced light-absorption losses and efficient charge transport between the CsPbBr₃ light absorber and the ZnO electron-transport layer. This ZnO/island-like CsPbBr₃ hybrid synaptic transistor could operate at a drain-source voltage of 1.0 V and a gate-source voltage of 0 V triggered by green light (500 nm) pulses with low light intensities of 0.035 mW/cm². The device exhibited a quiescent current of ~0.5 nA. Notably, after patterning, it achieved a significantly reduced off-state current of 10⁻¹¹ A and decreased the quiescent current to 0.02 nA. In addition, this transistor was able to mimic fundamental synaptic behaviors, including excitatory postsynaptic currents (EPSCs), paired-pulse facilitation (PPF), short-term to long-term plasticity (STP to LTP) transitions, and learning-experience behaviors. This straightforward strategy demonstrates the possibility of utilizing neuromorphic synaptic device applications under low voltage and weak light conditions. Full article