Search Results (660)

With the increasing emphasis on environmental protection and sustainable development, improving air pollution control technology has become imperative. In this study, Ce-based catalysts are used as research objects to explore the effects of hydrothermal aging on their performance in oxidizing PM. Different Mn, Na, Pt and Zr-doped Ce-based catalysts were prepared based on the impregnation method and the PM oxidation performance of Ce-based catalysts before and after hydrothermal aging was investigated using thermogravimetric experiments, and the catalytic activity change pattern of fresh/hydrothermal aging Ce-based catalysts was analyzed by comparing the comprehensive combustion index S and combustion stability index Rw, revealing the PM oxidation process. The conclusion showed that the cerium-based catalyst significantly enhanced the oxidation efficiency of PM compared with PU. By comparing the performance of different metal-modified catalysts, it was found that the order of activity was: Pt > Na > Mn > Zr. With the metal doping increased, only the comprehensive combustion index S and combustion stability index Rw of Na/CeO₂ catalysts decreased. After hydrothermal aging treatment, the Zr/CeO₂ catalysts showed the best hydrothermal aging resistance, and the comprehensive combustion index S and combustion stability index Rw remained stable (<5%). Ce-based catalysts have the strongest to weakest hydrothermal aging resistance in the following order: Zr > Mn > Pt > Na. This study not only provides an important scientific reference for the application of Ce-based catalysts in the field of environmental purification but also contributes new ideas and methods to promote the green and sustainable development of air pollution control technology. Full article

The long-term corrosion behavior of Al₂O₃-3%TiO₂ (AT3) coatings doped with1%, 5% and 8% CeO₂ prepared by plasma spraying was studied in 5% NaCl solution. The results showed that the protective performance of CeO₂-doped coatings was significantly higher than that of undoped coatings, primarily due to the reduction in coating porosity caused by the addition of rare-earth elements. Among the doped coatings, the 5% CeO₂-doped coating exhibited the best protective performance. The addition of rare-earth oxides CeO₂ reduced the content of γ-Al₂O₃ in the coating, but when the concentration of CeO₂ increased to 8%, the Ce element was rich in the gap of the coating. Excessive CeO₂ enriched in the gaps and coexisted more with Ti, and prevented the formation of the AlTi phase, which affected the performance of the coating. Electrochemical and XPS results revealed that an appropriate amount of Ce atoms or CeO₂ particles could fill the pores of the coating. During long-term immersion, Ce (IV) was converted to Ce (III), which demonstrated that Ce atoms have high chemical activity in coatings. The thermodynamic calculation results show that more CeO₂ particles improved the adsorption of corrosive ions. It indicated that the content of doped rare-earth oxides exceeding 5% would be utilized as an active material in the corrosive process. Full article

Precision and real-time detection of hydrogen peroxide (H₂O₂) are essential in pharmaceutical, industrial, and defence sectors due to its strong oxidizing nature. In this study, silver (Ag)-doped CeO₂/Ag₂O-modified glassy carbon electrode (Ag-CeO₂/Ag₂O/GCE) has been developed as a non-enzymatic electrochemical sensor for the sensitive and selective detection of H₂O₂. The synthesized Ag-doped CeO₂/Ag₂O nanocomposite was characterized using various advanced techniques, including X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), field-emission scanning electron microscopy (FE-SEM), and high-resolution transmission electron microscopy (HR-TEM). Their optical, magnetic, thermal, and chemical properties were further analyzed using UV–vis spectroscopy, electron paramagnetic resonance (EPR), thermogravimetric-differential thermal analysis (TG-DTA), and X-ray photoelectron spectroscopy (XPS). Electrochemical sensing performance was evaluated using cyclic voltammetry and amperometry. The Ag-CeO₂/Ag₂O/GCE exhibited superior electrocatalytic activity for H₂O₂, attributed to the increased number of active sites and enhanced electron transfer. The sensor displayed a high sensitivity of 2.728 µA cm⁻² µM⁻¹, significantly outperforming the undoped CeO₂/GCE (0.0404 µA cm⁻² µM⁻¹). The limit of detection (LOD) and limit of quantification (LOQ) were found to be 6.34 µM and 21.1 µM, respectively, within a broad linear detection range of 1 × 10⁻⁸ to 0.5 × 10⁻³ M. The sensor also demonstrated excellent selectivity with minimal interference from common analytes, along with outstanding storage stability, reproducibility, and repeatability. Owing to these attributes, the Ag-CeO₂/Ag₂O/GCE sensor proved effective for real sample analysis, showcasing its potential as a reliable, non-enzymatic platform for H₂O₂ detection. Full article

This study reports the hydrothermal synthesis, characterization, and Fenton-like catalytic performance of CeO₂–CoFe₂O₄ nanocomposites for degrading Congo Red (CR) dye and the oxytetracycline (OTC) antibiotic. A series of Ce-doped cobalt ferrite samples was prepared using a hydrothermal reaction. Additionally, the 50Ce-CFO sample was further activated with H₂O₂ treatment. XRD, FTIR, and SEM analyses confirmed the formation of a spinel phase alongside segregated CeO₂, which acts as a grain-growth inhibitor. The increased Ce content promotes particle amorphization. FTIR showed changes in the intensity of the M–O stretching band, indicating Ce-induced bond polarization in the spinel lattice. In H₂O₂ decomposition tests, the 50Ce-CFO catalyst fully decomposes H₂O₂ in 160 min, while the activated sample completes it in 125 min. Fenton-like degradation of CR and OTC by untreated and activated 50Ce-CFO sample followed pseudo-first-order kinetics. Catalyst stability was confirmed using post-reaction XRD, FTIR, and SEM analyses. Incorporation of CeO₂ into CoFe₂O₄ refines the crystallite size, increases the BET surface area, and enhances adsorption capacity, while the Ce⁴⁺/Ce³⁺ redox couple promotes reactive oxygen species generation. Owing to this dual structural and catalytic role, the CeO₂-CoFe₂O₄ composites exhibit significantly improved Fenton-like catalytic activity, enabling the efficient degradation of organic pollutants. Full article

With the advent of novel scintillators featuring higher atomic numbers and enhanced radiation hardness, these materials exhibit potential applications under high-dose-rate irradiation. In this work, we systematically compared the photon output characteristics of ten mainstream or emerging inorganic scintillators under high-dose-rate irradiation with low-energy (0.1–1.7 MeV) electrons or protons. Initially, under electron irradiation among ~0.1 to ~50 rad/s, responses exhibited saturation trends to varying degrees, with their variations conforming to the saturation model proposed. However, under proton irradiation among ~5 rad/s to ~150 rad/s, responses exhibited sigmoidal trends due to competition between radiation-induced defects and luminescence centers. Through dynamic derivation of carriers and them, a triple-balance model that demonstrated close agreement with such variations was established. Subsequently, energy-dependent responses under proton irradiation exhibited marked nonlinearity, which were well fitted by Birks’ law, confirming the validity of our measurements. In contrast, electron-induced responses remained nearly linear with increasing energy. Then, after high-dose-rate and prolonged irradiation, BGO revealed highest response degradation, while YAG(Ce) demonstrated most radiation-damage resistance. Moreover, Ce-doped scintillators displayed higher afterglow levels after prolonged irradiation, particularly for YAG(Ce). In summary, these experimental analyses can provide critical guidance for material selection and effective calibration of scintillator detectors operating under high-dose-rate radiation from charged particles. Full article

In this study, we developed and characterized novel scintillators with Ce: LiCaAlF₆–CaF₂–Li₃AlF₆ and Ce: CaF₂–LiF–Li₃AlF₆ ternary systems for thermal neutron detectors. The eutectics were grown by the vertical Stochbarger-Bridgman (VB) technique, and their constituent phases were identified using powder X-ray diffraction and scanning electron microscopy. Radioluminescence spectra irradiated under an Ag-target X-ray tube and confirmed the 5d-4f and self-trapped exciton luminescence derived from Ce³⁺. Scintillation decay and pulse height measurements were performed using ²⁵²Cf and ⁶⁰Co sources. The Ce: CaF₂–LiF–Li₃AlF₆ sample exhibited approximately 5.6 times higher effective neutron sensitivity compared with a Ce: LiCaAlF₆ single crystal. A favorable decrease in the neutron discrimination threshold level (Q_th) due to reduced γ-ray emission was observed. ⁶Li-enriched Ce: CaF-based scintillators hold potential for nuclear decommissioning applications. Full article

Cerium-doped zinc cobaltite spinel thin films, $\mathrm{Z}\mathrm{n}{\mathrm{C}\mathrm{e}}_{\mathrm{x}}{\mathrm{C}\mathrm{o}}_{2-\mathrm{x}}{\mathrm{O}}_4 (0.00\le \mathrm{x}\le 0.05)$, were synthesized via spray pyrolysis, and their structural, morphological, optical, and electrical properties were analyzed. X-ray diffraction (XRD) confirmed a cubic spinel structure with a predominant (311) orientation across all compositions. Raman spectroscopy further verified this phase, revealing four active vibrational modes at 180 cm⁻¹, 470 cm⁻¹, 515 cm⁻¹, and 682 cm⁻¹. Scanning electron microscopy (SEM) indicated a uniform grain distribution, while energy-dispersive X-ray spectroscopy (EDS) confirmed the presence of Ce, Zn, Co, and O. Optical measurements revealed two distinct bandgaps, decreasing from 2.32 eV to 2.20 eV for the lower-energy transition and from 3.38 eV to 3.18 eV for the higher-energy transition. Hall effect measurements confirmed p-type conductivity in all films. Electrical analysis showed a reduction in resistivity, from 280.3 Ω·cm to 15.4 Ω·cm, along with an increase in carrier concentration from 1.15 × 10¹⁶ cm⁻³ to 8.15 × 10¹⁷ cm⁻³ with higher Ce content. These results demonstrate that spray pyrolysis is a cost-effective and scalable method for producing Ce-doped ZnCo₂O₄ thin films with tunable properties, making them suitable for electronic and optoelectronic applications. 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

During the annealing, recrystallization processes in ceramics can occur, manifested in the formation of new grains, grain-boundary migration, and grain coarsening. It was expected that recrystallization in mechanically deformed zones, which contain residual stresses and high defect densities, will proceed in a different way compared to the surrounding, relaxed material. Characterizing these spatial variations in defect evolution, phase transformations, and microstructural recovery is essential for predicting performance and avoiding critical structural changes when designing zirconia-based ceramics for high-temperature, load-bearing applications. To study these effects, we used partially stabilized Ce-doped ZrO₂ ceramics, fabricated by solid-state synthesis. Phase composition, structural features, and morphology of these ceramics were studied using Raman spectroscopy, XRD and SEM before and after annealing in the mechanically stressed and relaxed regions. In mechanically deformed regions a more pronounced phase transformation from monoclinic to tetragonal was observed compared to relaxed zones. This result indicates that strain can facilitate tetragonal phase formation in zirconia ceramics when the material is subjected to elevated temperatures. Mechanical stresses should be taken into account when fabricating ceramic components, as they can induce phase transformation during heat treatments and change the properties of ceramics significantly. Full article

The persistent occurrence of antibiotics like chloramphenicol (CAP) in aquatic systems poses serious environmental and public health risks. This study investigates the photocatalytic degradation of CAP using cerium oxide (CeO₂), lanthanum oxide (La₂O₃), and lanthanum-doped cerium oxide (Ce_xLa_yO_2−δ), synthesized via co-precipitation. The catalysts were tested under a solar simulator, UV-A, and UV-C radiation, both with and without hydrogen peroxide (H₂O₂). Structural characterization confirmed successful synthesis of nanometric catalysts, with La doping causing lattice expansion in CeO₂ and a reduction in crystallite size (from 27 nm in CeO₂ to ~20 nm in doped samples). Photolysis alone achieved limited CAP removal (~34–35%), while photocatalysis with La₂O₃ under UV-A and UV-C improved removal up to 58% and 55%, respectively. Complete degradation was obtained with La₂O₃ under UV-C in the presence of H₂O₂ within 15 min. Pareto analysis highlighted the dominant effect of the interaction between radiation and H₂O₂ (43%), while the catalyst type contributed minimally (0.23%). These findings confirm the potential of REE oxides, especially La₂O₃, in advanced oxidation processes and underscore the importance of light source and radical generation over catalyst selection alone. Full article

A series of Ce-doped α-MnO₂ catalysts (Ce_XMn_1−XO₂, x = 0.04, 0.07, 0.10) were synthesized by a simple in situ hydrothermal method. It was confirmed by characterization methods such as XRD, Raman, N₂ adsorption–desorption and SEM confirmed that the introduction of Ce significantly regulated the microstructure of α-MnO₂, specifically manifested as the reduction in grain size, the increase in defect sites, the increase in Mn-O bond length and altered morphological structure. H₂-TPR, O₂-TPD and XPS analyses further revealed the strong interaction between Mn and Ce, accompanied by significant electron transfer (Ce³⁺ + Mn⁴⁺ → Ce⁴⁺ + Mn³⁺), thereby promoting the formation of Mn³⁺ species. In the test of toluene catalytic oxidation performance, C_e0.07Mn_0.93O₂ exhibited the most excellent catalytic activity (T₁₀₀ = 280 °C), while also having good thermal stability and water resistance. Furthermore, the degradation pathways of toluene were analyzed by TD-GC-MS technology: Toluene → Benzene → Benzaldehyde → Maleic anhydride → CO₂ and H₂O. Full article

Air pollution and the emission of toxic gases represent a critical global concern, posing significant threats to human health and environmental stability. Resistive gas sensors are widely employed to detect toxic gases, owing to their cost-effectiveness, high stability, sensitivity, and swift dynamics. Among various sensing materials, comparatively less attention has been paid to CeO₂ despite its good catalytic activity and high stability. In this review paper, we are focusing on CeO₂ gas sensors in pristine, doped, decorated, and composite forms. Using numerous examples, we have shown the great potential of CeO₂ for gas sensing. The main features of CeO₂ as a gas sensor include excellent environmental stability, the abundance of oxygen vacancies, high mechanical strength, cost-effectiveness, and good catalytic activity. However, low electrical conductivity is the main shortage of CeO₂ as a gas sensor. With a high emphasis on the sensing mechanism, we believe that this review paper is highly useful for researchers working in this field. 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

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