Search Results (114)

To improve the sluggish low-temperature hydrogen storage kinetics of RE-Mg-based alloys, Bi₂O₃ is introduced into CeMg₁₁Ni as a functional dopant for microstructural regulation, and CeMg₁₁Ni + x wt.% Bi₂O₃ (x = 0, 3, 5, 7, 10) composites are fabricated through planetary ball milling. Multiple characterization methods including XRD, SEM and TEM were used to explore the effects of Bi₂O₃ on the microstructure and hydrogen storage properties. Bi₂O₃ maintains stable phase during cycling and does not participate in reversible hydrogen storage reactions. It cooperates with in situ formed CeH₂ nanocrystals to construct high-density interfacial defects. The 5 wt.% Bi₂O₃-doped alloy exhibits the optimal balance between exposed catalytic sites and open hydrogen diffusion channels, achieving complete dehydrogenation within 144 s at 633 K, a reduced dehydrogenation activation energy of 63.89 kJ mol⁻¹, and an 84.7% hydrogen absorption ratio within 5 min at 423 K. Bi₂O₃ has a weak effect on the thermodynamic properties of the alloy, with only a slight enthalpy change of less than 1 kJ/mol within the experimental error range. Bi₂O₃ enhances hydrogen storage reactions through a synergistic “active sites–diffusion channels” mechanism, in which oxygen vacancies promote H₂ dissociation and heterogeneous interfaces facilitate hydrogen diffusion, thereby reducing the reaction energy barrier. Full article

Despite its critical role in disease diagnosis as a radiopharmaceutical, Fluorine-18 generates medical wastewater that necessitates efficient treatment, for which membrane adsorption stands out as a potent method, albeit one that demands high-performance membranes with exceptional permeability and adsorption capacity. This study presents a novel cerium-loaded amyloid fibril hybrid membrane designed for efficient removal of fluorine-18 from such wastewater. The membrane is fabricated through a facile process involving oxidation–precipitation of cerium species onto amyloid fibrils, followed by vacuum filtration, with further compositional tuning via incorporation of porous silica or activated carbon dopants. The resulting membrane retains the characteristic amyloid fibril structure and exhibits high water permeability with a flux of up to 803.3 L/(m²·h·bar), superior to most of the other membrane materials. It effectively removes fluoride ions (F⁻) from both low and high-concentration solutions, achieving a removal efficiency of up to 99% and a maximum adsorption capacity of 580 mg/g, outperforming many existing membrane materials. The hybrid membrane also demonstrates notable resistance to ionic interference, enabling selective F⁻ adsorption from solutions containing high concentrations of Cl⁻, NO₃⁻ and SO₄²⁻, with a distribution coefficient (Kd) as high as 4.1 × 10⁴ mL/g; furthermore, it maintains a fluoride removal rate above 51% after ten consecutive adsorption cycles. The membrane retains 51% of its initial fluoride removal efficiency after 10 cycles, indicating potential for repeated use, although further optimization or regeneration strategies would be required to fully restore performance. Mechanistic investigations reveal that F⁻ adsorption occurs mainly through ion exchange with hydroxyl groups on CeO₂. This work introduces a promising novel material with significant potential for the efficient treatment of medical radioactive wastewater containing fluorine-18. Full article

CeO₂ is a representative oxygen-storage oxide because its fluorite lattice can reversibly release and reincorporate oxygen through the Ce⁴⁺/Ce³⁺ redox couple and the associated formation and annihilation of oxygen vacancies. Although doped CeO₂ has been studied extensively, the literature has often treated oxygen-storage enhancement mainly in terms of dopant identity and composition, whereas the more fundamental issue is how a given doping strategy constructs a specific defect state within the fluorite host. Here, oxygen-storage enhancement is discussed from the standpoint of defect-state engineering. The discussion focuses on three routes, as follows: rare-earth single doping, cation–anion co-doping, and route-dependent dopant incorporation. Rare-earth single doping correlates aliovalent substitution with lattice expansion, vacancy generation, and finite oxygen-storage-capacity (OSC) optima. Cation–anion co-doping further shows that simultaneous perturbation of the cationic and anionic sublattices can amplify the defect response, while also demonstrating that vacancy concentration alone does not fully account for OSC enhancement. Route-dependent doping adds an additional dimension by showing that the same dopant can produce different lattice responses, defect populations, and oxygen-release behaviors when introduced through different pathways. On this basis, the review argues that OSC in doped CeO₂ is more meaningfully rationalized through a coupled descriptor set involving lattice accommodation, Ce³⁺/Ce⁴⁺ redistribution, oxygen-vacancy abundance, and dopant incorporation pathway. Taken together, these observations shift the design logic of oxygen-storage ceria from empirical dopant screening toward deliberate defect-state construction. Full article

In advanced oxide materials, additive selection is increasingly constrained by the simultaneous requirements of functional response, phase stability, morphology control, processing tolerance, scalability, and critical raw material security. This study develops a ZnO-centered framework to compare boron-based strategies (direct B doping, B₄C/ZnO composite formation, and h-BN/ZnO interface engineering) with rare-earth strategies (Ce/CeO₂, La/La₂O₃, and Y/Y₂O₃). Structural, morphological, chemical-state, and vibrational evidence from XRD, FE-SEM/EDX, XPS, Raman, and FT-IR studies is interpreted through an evidence hierarchy that separates lattice incorporation, surface/grain-boundary segregation, and deliberate secondary-phase or heterointerface formation. The synthesis shows that boron-containing routes usually provide broader phase retention, lower agglomeration tendency, more gradual defect modulation, and greater processing robustness, whereas rare-earth routes offer stronger oxygen-vacancy regulation, redox activity, luminescence tuning, and heterojunction-assisted function but require tighter process control and more rigorous verification of incorporation mode. Reanalysis of seven primary experimental pathways indicates that B₄C/ZnO and h-BN/ZnO are mechanistically non-equivalent: B₄C supports rigid composite-interface growth, while h-BN promotes sheet-mediated interface multiplication and Maxwell–Wagner–Sillars polarization. Türkiye is treated as an illustrative boron-rich producer case within a transferable producer/importer decision model. Dopant selection is therefore framed as a multi-criteria decision involving performance thresholds, reproducibility, technology-readiness potential, and supply-security exposure, not peak output alone. Full article

This study presents an experimental investigation of the influence of dopant type and calcination temperature on BaTiO₃-based piezoceramics synthesized by a solid-state calcination process. The effects of Mn, Nb, La, and Ce dopants on the structural, morphological, and piezoelectric characteristics of powders calcined at 1000 °C and 1100 °C were systematically evaluated. In addition, two co-doped BaTiO₃ compositions, namely Mn–Nb and La–Nb, calcined at 1000 °C, were investigated in order to assess the combined effect of acceptor–donor and donor–donor doping strategies on microstructural evolution and structural stability. The synthesized powders were characterized by scanning electron microscopy (SEM), particle size analysis, energy-dispersive X-ray spectroscopy (EDS), elemental mapping, and X-ray diffraction (XRD), in comparison with a commercial BaTiO₃ reference powder. The piezoelectric response was assessed by correlating the structural modifications induced by doping with the estimated piezoelectric coefficient d₃₃, calculated as a function of the tetragonality ratio (c/a) and further correlated with the crystallite size. The results reveal significant variations in grain growth, dopant distribution, and crystallographic stability, highlighting the critical role of dopant chemistry and calcination temperature in tailoring the functional properties of BaTiO₃ for piezoelectric applications. Full article

Mesoporous bioactive glass nanoparticles (MBGNs) are promising for bone tissue engineering; however, surgical site infection and oxidative stress often compromise regeneration. To address this, MBGNs co-doped with cerium (Ce), zinc (Zn), and strontium (Sr) were synthesized using a microemulsion-assisted sol-gel route (xCe-yZn-Sr-MBGNs; x = 0, 1, 2; y = 0, 0.5, 1). The resulting spherical nanoparticles (150–200 nm) exhibited a mesoporous structure with a specific surface area of (~340–425 m²/g), sustained ion release, and apatite formation in simulated body fluid. In vitro evaluations with MC3T3-E1 pre-osteoblasts demonstrated dose-dependent cytocompatibility, specifically in the co-doped formulations; however, higher Ce concentrations (2Ce-yZn-Sr-MBGNs) reduced viability following prolonged exposure. Crucially, the 1Ce-1Zn-Sr-MBGNs significantly enhanced osteogenic differentiation, as evidenced by a two-fold increase in osteogenic marker gene expression and a ~45% increase in calcium mineral deposition compared to undoped MBGNs within 14 days. Moreover, these particles accelerated cell migration, achieving ~70% scratch-wound closure within 24 h. Furthermore, 1Ce-1Zn-Sr-MBGNs displayed strong radical scavenging capacity and potent antibacterial activity against S. aureus and P. aeruginosa. These findings indicated that 1Ce-1Zn-Sr-MBGNs exhibited multiple therapeutic effects, including antibacterial, radical-scavenging, and osteogenic effects. By optimizing dopant ratios, these multifunctional nanomaterials emerge as promising candidates for next-generation bone grafts or implant coatings. Within the scope of this study, they demonstrated the capacity to simultaneously address three critical challenges in bone healing: controlling infection, mitigating oxidative stress, and promoting mineralized tissue formation. While these in vitro results provide a robust foundation, further in vivo validation is warranted to confirm their efficacy within complex physiological environments. Full article

Cerium oxide (CeO₂) nanozymes, also known as nanoceria have emerged as a versatile class of catalytic nanomaterials capable of mimicking key redox enzymes, including oxidases and peroxidases. Their tunable Ce³⁺/Ce⁴⁺ redox cycling, high density of oxygen vacancies, and exceptional resistance to thermal, pH, and storage stress distinguish CeO₂ from conventional enzyme labels, such as horseradish peroxidase (HRP). In immunoassays, CeO₂ enables H₂O₂-free TMB (3,3′,5,5′-tetramethylbenzidine) oxidation, generating strong chromogenic signals with minimal background. Although CeO₂ nanozymes have been explored in colorimetric, chemiluminescent, and photoactive immunoassays, their integration into lateral flow immunoassays (LFIAs) remains limited, with only a few hybrid CeO₂-containing systems reported to date. This mini-review highlights the limitations of conventional peroxidase-based formats and explains how CeO₂’s redox cycling (Ce³⁺/Ce⁴⁺) and oxygen-vacancy-driven catalysis deliver stable, reagent-free signal amplification. Emphasis is placed on the synthetic control of CeO₂, conjugation chemistry with antibodies, and integration into LFIA architectures. CeO₂ enables hydrogen-peroxide-free colorimetric detection with improved robustness and sensitivity, positioning it as a promising catalytic label for point-of-care testing. However, it may aggregate in high-ionic-strength buffers, and its synthesis cost increases for highly uniform, vacancy-engineered materials. Surface functionalization with polymers or dopants and optimized dispersion strategies can mitigate these issues, guiding future practical implementations. Full article

Rare-earth fluoride nanocrystals have emerged as promising scintillator materials due to their excellent optical properties, environmental stability, and ease of fabrication into flexible screens. However, their practical application is often hindered by persistent afterglow, a phenomenon caused by deep trap states that capture and slowly release charge carriers after X-ray excitation, which leads to signal overlap and image artifacts in dynamic imaging scenarios. This study addresses this critical challenge by developing Ce³⁺/Tb³⁺ co-doped NaLuF₄ nanoscintillators with suppressed afterglow. By introducing Ce³⁺ions as dopants into the Tb³⁺-activated NaLuF₄ host, we successfully quenched the characteristic long afterglow without compromising the intrinsic radioluminescence efficiency of the Tb³⁺ centers. The optimized nanocrystals were subsequently incorporated into a poly (vinyl alcohol) matrix to fabricate transparent, high-loading composite scintillator films. The resulting films exhibit negligible afterglow, maintain high spatial resolution, and demonstrate excellent radiation stability. This work presents an effective strategy for suppressing afterglow in rare-earth fluoride scintillators through targeted ion doping, which paves the way for their application in real-time, high-quality X-ray imaging technologies such as medical diagnostics and industrial inspection. Full article

Advanced ceramics are known for their lightweight, high-temperature resistance, corrosion resistance, and biocompatibility. They are crucial in energy conversion, environmental protection, and aerospace fields. This review highlights the recent advancements in ceramic matrix composites, high-entropy ceramics, and polymer-derived ceramics, alongside various fabrication techniques such as three-dimensional printing, advanced sintering, and electric-field-assisted joining. Beyond the fabrication process, we emphasize how different processing methods impact microstructure, transport properties, and performance metrics relevant to catalysis. Additive manufacturing routes, such as direct ink writing, digital light processing, and binder jetting, are discussed and normalized based on factors such as relative density, grain size, pore architecture, and shrinkage. Cold and flash sintering methods are also examined, focusing on grain-boundary chemistry, dopant compatibility, and scalability for catalyst supports. Additionally, polymer-derived ceramics (SiOC, SiCN, SiBCN) are reviewed in terms of their catalytic performance in hydrogen evolution reaction, oxygen evolution reaction, oxygen reduction reaction, and CO₂ reduction reaction. CeO₂-ZrO₂ composites are particularly highlighted for their use in environmental catalysis and high-temperature gas sensing. Furthermore, insights on the future industrialization, cross-disciplinary integration, and performance improvements in catalytic applications are provided. Full article

Rare-earth oxide (REO) nanoparticles (NPs)—such as cerium (CeO₂), samarium (Sm₂O₃), neodymium (Nd₂O₃), terbium (Tb₄O₇), and praseodymium (Pr₂O₃)—have demonstrated strong antimicrobial activity against multidrug-resistant bacteria. Their effectiveness is attributed to unique physicochemical properties, including oxygen vacancies and redox cycling, which facilitate the generation of reactive oxygen species (ROS) that damage microbial membranes and biomolecules. Additionally, electrostatic interactions with microbial surfaces and sustained ion release contribute to membrane disruption and long-term antimicrobial effects. REOs also inhibit bacterial enzymes, DNA, and protein synthesis, providing broad-spectrum activity against Gram-positive, Gram-negative, and fungal pathogens. However, dose-dependent cytotoxicity to mammalian cells—primarily due to excessive ROS generation—and nanoparticle aggregation in biological media remain challenges. Surface functionalization with polymers, peptides, or metal dopants (e.g., Ag, Zn, and Cu) can mitigate cytotoxicity and enhance selectivity. Scalable and sustainable synthesis remains a challenge due to high synthesis costs and scalability issues in industrial production. Green and biogenic routes using plant or microbial extracts can produce REOs at lower cost and with improved safety. Advanced continuous flow and microwave-assisted synthesis offer improved particle uniformity and production yields. Biomedical applications include antimicrobial coatings, wound dressings, and hybrid nanozyme systems for oxidative disinfection. However, comprehensive and intensive toxicological evaluations, along with regulatory frameworks, are required before clinical deployment. Full article

DFT calculations have been employed to investigate the impact of Sm dopant(s) on the structure and stability of periodic CeO₂(111) slab and Ce₁₄₀O₂₈₀ nanoparticle systems. We found that substituting Ce ion(s) with Sm ion(s) in the surface layer yields the most favorable doped configurations in both systems. Further, we evaluated how Sm ion(s) modify the reducibility of the systems—a key process in the catalytic applications of ceria. It has been found that a substantial reduction in oxygen vacancy formation energy occurs due to the presence of Sm ion(s), with values of 1.24 and 0.29 eV for mono- and bi-doped CeO₂(111), respectively, which are considerably lower than 2.43 eV obtained for the pristine ceria slab. As the system changes from slab to nanoparticle, mono-doping reduces this energy to 0.25 eV—about four times lower than that calculated for the pristine Ce₁₄₀O₂₈₀ nanoparticle. The presence of a second Sm ion within the nanoparticle leads to a dramatic decrease in E_vac, making the reduction process exothermic. In either slab or nanoparticle models, the Sm³⁺ ions prefer to be in close proximity to each other, and the formation of oxygen vacancies is most energetically favorable in the vicinity of Sm³⁺ ions. Full article

The activity of Co- and Ni-containing ceria-based catalysts for water–gas shift (WGS) reaction were examined in this work. The catalysts were prepared by the urea co-precipitation method. Sm and Pr dopant (5 wt.%) was used as a structural stabilizer of CeO₂, while Co or Ni was used in a small amount (1 wt.%). H₂-TPR experiments indicate that both Sm and Pr addition increased the reducibility of CeO₂. Among the studies’ catalysts, 1%Ni/Ce5%SmO exhibited the highest WGS activity. In addition, WGS rate was measured in the temperature range of 200–400 °C for Ni supported on CeO₂, Ce5%SmO, and Ce5%PrO. The activation energy of the reaction over 1%Ni/Ce5%SmO was 57 kJ/mol, while it was 61 and 66 kJ/mol, respectively, over 1%Ni/Ce5%PrO and 1%Ni/CeO₂ catalysts. A WGS reaction mechanism, CO adsorbed on the metal cluster is oxidized by oxygen supplied from the CeO₂ support at the metal–ceria interface. This oxygen is then re-oxidized by H₂O, which caps the oxygen vacancy on the ceria surface, and thereby oxygen vacancies serve as active sites for the WGS reaction. Raman experiments indicate that the presence of Sm in 1%Ni/Ce5%SmO catalyst promoted the formation of oxygen vacancies, leading to enhanced WGS performance. Full article

Over more than half a century of using zirconia in technology and industry, researchers have faced several challenges related to the performance of this material. It is believed that some issues regarding the low performance of the zirconia ceramics can be solved by using a multidoping strategy. In this study, nanoparticles with the composition (1 − x)⸱ZrO₂ − x⸱MD (where MD—multi-dopant Y:Ce:Mg:Ca with cation relationship 1:1:1:1 and x = 0.05–0.25 mol. %) were synthesized using a hydrothermal method followed by annealing. XRD and Raman spectroscopy analyses demonstrated that in the concentration range of x = 0.10–0.25 mol.%, the only detectable phase in the synthesized samples was the tetragonal phase of zirconia. SEM analysis revealed that the size of the final particles ranged from 20 to 50 nm. It was demonstrated that using obtained nanoparticles as precursors for sintering leads to the formation of multiphase ceramics. The microhardness and biaxial flexural strength of the ceramic samples vary depending on the dopant concentration in the range of 600–1400 HV and 25–200 MPa respectively. Mechanical properties mostly depend on porosity and grain size in the sintered material. The study shows that the multidoping strategy has high potential to obtain new constructional ceramics and components for solid oxide fuel cells. Full article

Facing energy and environmental issues is recognized globally as one of the major challenges for sustainable development, to which sustainable chemistry can make significant contributions. Strontium ferrate-based materials belong to a little-known class of perovskite-type compounds in which iron is primarily stabilized in the unusual 4+ oxidation state, although some Fe³⁺ is often present, depending on the synthesis and processing conditions and the type and amount of dopant. When doped with cerium at the Sr site, the SrFeO_3−δ cubic structure is stabilized, more oxygen vacancies form and the Fe⁴⁺/Fe³⁺ redox couple plays a key role in its functional properties. Alone or combined with other materials, Ce-doped strontium ferrates can be successfully applied to wastewater treatment. Specific doping at the Fe site enhances their electronic conductivity for use as electrodes in solid oxide fuel cells and electrolyzers. Their oxygen storage capacity and oxygen mobility are also exploited in chemical looping reactions. The main limitations of these materials are SrCO₃ formation, especially at the surface; their low surface area and porosity; and cation leaching at acidic pH values. However, these limitations can be partially addressed through careful selection of synthesis, processing and testing conditions. This review highlights the high versatility and efficiency of cerium-doped strontium ferrates for energy and environmental applications, both at low and high temperatures. The main literature on these compounds is reviewed to highlight the impact of their key properties and synthesis and processing parameters on their applicability as sustainable thermocatalysts, electrocatalysts, oxygen carriers and sensors. Full article

This work presents a comprehensive study of the structural, luminescent, and photoconversion properties of epitaxial composite phosphor converters based on single crystalline films of Ce³⁺-activated Ca_2−xY_1+xMg_1+xSc_1−xSi₃O₁₂:Ce (x = 0–0.25) (CYMSSG:Ce) garnet, grown using the liquid phase epitaxy (LPE) method on single-crystal Y₃Al₅O₁₂ (YAG) and YAG:Ce substrates. The main goal of this study is to elucidate the structure–composition–property relationships that influence the photoluminescence and photoconversion efficiency of these film–substrate composite converters, aiming to optimize their performance in high-power white light-emitting diode (WLED) applications. Systematic variation in the Y³⁺/Sc³⁺/Mg²⁺ cationic ratios within the garnet structure, combined with the controlled tuning of film thickness (ranging from 19 to 67 µm for CYMSSG:Ce/YAG and 10–22 µm for CYMSSG:Ce/YAG:Ce structures), enabled the precise modulation of their photoconversion properties. Prototypes of phosphor-converted WLEDs (pc-WLEDs) were developed based on these epitaxial structures to assess their performance and investigate how the content and thickness of SCFs affect the colorimetric properties of SCFs and composite converters. Clear trends were observed in the Ce³⁺ emission peak position, intensity, and color rendering, induced by the Y³⁺/Sc³⁺/Mg²⁺ cation substitution in the film converter, film thickness, and activator concentrations in the substrate and film. These results may be useful for the design of epitaxial phosphor converters with tunable emission spectra based on the epitaxially grown structures of garnet compounds. Full article