Nanoparticles Of CeO2 Research Articles

Construction of a novel S-type γ-Bi2O3/CeO2 heterojunction for highly efficient photocatalytic degradation of antibiotics.

Cubic nanoparticles of CeO2 were partly covered on the tetrahedron surface of γ-Bi2O3 through a hydrothermal reaction and then a calcination process to construct a novel S-type γ-Bi2O3/CeO2 heterojunction. The optimized sample removed 96% of lomefloxacin and 81% of tetracycline. During the cycling test, the photocatalytic efficiency of lomefloxacin and tetracycline was maintained above 87% and 80%, respectively, for five consecutive cycles. According to XRD and Raman spectra characterization, the sample after cycling held a stable crystal structure. Holes, OH-˙, O2˙, and electrons participated in the degradation of lomefloxacin, while tetracycline was removed via the effect of the former three active substances. Based on theoretical calculation and experimental tests, the excellent photocatalytic activity of γ-Bi2O3/CeO2 came from the fast transfer of charge carriers along the S-type path. Moreover, the CB electrons of γ-Bi2O3 and VB holes of CeO2 were preserved to generate free radicals for antibiotic degradation. The colony numbers of Escherichia coli were 1.50 × 10-6 CFU mL-1 and 1.39 × 10-6 CFU mL-1 in solutions after the degradation of the two pollutants, which represents the non-toxicity of the final products. The γ-Bi2O3/CeO2 sample has a potential application for antibiotic removal from modern sewage.

Optical properties of aluminum oxide powder modified by nanoparticles and prospects for its use in solar power and space industry

Studies on the phase composition, diffuse reflectance spectra (ρλ) and solar absorptance (αs) and their changes after modification of aluminum oxide powder by nanoparticles of cerium dioxide, magnesium oxide, silicon dioxide, titanium dioxide and zinc oxide are presented. The diffuse reflectance spectra and solar absorptance αs of nanoparticles used for modification were studied.In its initial state, Al2O3 was found to exhibit high reflectivity. The obtained value of the solar absorptance, 0.074, was significantly less than that of the widely used white reflective powders – ZnO and TiO2. After modification by nanoparticles of wide-band compounds, MgO and SiO2, the reflectivity of Al2O3 powder changed slightly. Modification by SiO2 nanoparticles at a concentration of 1 wt % decreased the solar absorptance to 0.064. At small concentrations (0.1–1 wt. %) of nanoparticles of semiconductor compounds, CeO2, TiO2 and ZnO, the absorption edge of Al2O3 powder shifted to a longer wavelength region of the spectrum. At 10 wt % concentration of nanoparticles, the absorption edge of Al2O3 powder shifted to a value close to the absorption edge of the initial nanopowders.Such nano-micropowder systems can be used to develop new materials with improved optical properties for solar power and space technology applications, as well as other applications that need high reflectance and low solar absorptance. New data on shifts of the main absorption edge after modification by semiconductor nanoparticles can be useful in developing new materials for photocatalysis.

Oxygen vacancy driven luminescence, ferromagnetic and electronic structure properties of Eu doped CeO2 nanoparticles

Chemical co-precipitation route prepared nanoparticles of CeO2 and rare-earth cation Eu- doped Ceria Ce1-xEuxO2 (x = 0.03, 0.05, and 0.07) were investigated for various properties. Strained and phase maintained doped nanoparticles with crystallite sizes between 13 and 26 nm were confirmed by XRD, Rietveld refinement and UV–Vis–NIR measurements. Strained nanoparticles by replacement of host Ce with Eu in +2 and + 3 states were confirmed by X-ray Photoelectron Spectroscopy analyses which also, relate the crop of oxygen vacancies with the concentration of Eu doping by analysing Ce3+/Ce4+ ratio. Formation of various complexes involving host and doped cations and mediated by oxygen vacancies indicate the formation of F0, F+ and F2+ centres. Photoluminescence studies and their CIE chromaticity diagram underline the possible usage of these nanoparticles in Light Emitting Diodes due to production of light under 5000K. All the characterization techniques were on the same page in indicating our findings. F-centre exchange (FCE) and Bound Magnetic Polarons (BMP) mechanisms were underlined for the observed weak ferromagnetic behaviour along with M-T studies. A systematic study on the concentration of Eu-doping in CeO2 nano-particle to understand the role of oxygen vacancies and their effect on tailoring the luminescence, electronic structure and magnetic properties for variety of applications.

Synthesis and characterization of zinc oxide and cerium dioxide nanoparticles with possible application for nitrite ions removal in waters

Nitrite ion, a characteristic pollutant, can be removed from water by reverse osmosis, distillation, or ion exchange resin. In this study, we removed it by using ZnO and CeO2 nanoparticles. First, zinc hydroxide and cerium hydroxide were prepared by the hydrothermal method and heated at 90°C to dry. Second, they were annealed at 400°C to produce nanoparticles of ZnO and CeO2, respectively. The obtained samples were characterized by X-ray diffraction to ascertain their structure and chemical composition. The surface morphology analysis of the nanoparticles was performed using scanning electron microscopy. Atomic force microscopy was employed to characterize the imaging surface and ascertain the surface roughness. The functional groups present at the surface of the nanoparticles were investigated using the Fourier transform infrared spectroscopy method. The optical properties of these particles were investigated using the UV-visible spectroscopy. Further, the produced nanoparticles were used to adsorb NO2- ions from aqueous solutions. The results showed that the nanoparticles which were heated at 90°C (hydroxide forms) presented a higher activity for nitrite ions removal than those that were heated at 400°C (oxide forms). This may be related to nitrite ions preferential adsorption to hydroxide forms rather than to oxide forms; in both cases (90°C and 400°C), zinc oxide nanoparticles presented higher nitrite removal activity.

Surface-Related Factors Affecting the Photocatalytic Process of Semiconductor Oxides: Ceria and Titania

Nanoparticles of CeO2, with rod-, and cubic-morphology, were synthesized by hydrothermal method and compared with commercial polyhedral ceria particles. Comparison of the synthesized CeO2 with the commercial powder revealed the influence of its defectivity with the absorption edge energy. The defectivity of CeO2 has also been determined in correlation with the photocatalytic performance of CeO2 per unit particles area, under narrow band UV-light (LED) condition. Analysis of the photocatalytic performance of the synthesized and commercial CeO2, as well as the reference TiO2 powder, revealed an enhancement in the decolorization of methylene blue dye (MB) with pH. The improvement in photocatalysis was associated with the surface charge condition of CeO2 particles, which controls the adsorption of molecules during the process. Furthermore, it was observed that the highly negative surface charge of cubic-morphology CeO2 favored the decolorization of MB, despite the low BET surface area. The photoelectrochemical study of ceria electrodes revealed a low photopotential compared to that of TiO2, the impact of which leads to a worse photocatalytic performance of CeO2 compared to TiO2.

Fe-Ce/Layered Double Hydroxide Heterostructures and Their Derived Oxides: Electrochemical Characterization and Light-Driven Catalysis for the Degradation of Phenol from Water

Fe-Ce/layered double hydroxides (LDHs) were synthesized via a facile route by exploiting the "structural memory" of the LDH when the calcined MgAlLDH and ZnAlLDH were reconstructed in the aqueous solutions of FeSO4/Ce(SO4)2. XRD analysis shows the formation of heterostructured catalysts that entangle the structural characteristics of the LDHs with those of Fe2O3 and CeO2. Furthermore, X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, TG/DTG, SEM/EDX and TEM results reveal a complex morphology defined by the large nano/microplates of the reconstructed LDHs that are tightly covered with nanoparticles of Fe2O3 and CeO2. Calcination at 850 °C promoted the formation of highly crystallized mixed oxides of Fe2O3/CeO2/ZnO and spinels. The photo-electrochemical behavior of Fe-Ce/LDHs and their derived oxides was studied in a three-electrode photo-electrochemical cell, using linear sweep voltammetry (LSV), Mott-Schottky (M-S) analysis and photo-electrochemical impedance spectroscopy (PEIS) measurements, in dark or under illumination. When tested as novel catalysts for the degradation of phenol from aqueous solutions, the light-driven catalytic heterojunctions of Fe-Ce/LDH and their derived oxides reveal their capabilities to efficiently remove phenol from water, under both UV and solar irradiation.

Green Nanotechnology: Recent Research on Bioresource-Based Nanoparticle Synthesis and Applications

In the last decades, the idea of green nanotechnology has been expanding, and researchers are developing greener and more sustainable techniques for synthesizing nanoparticles (NPs). The major objectives are to fabricate NPs using simple, sustainable, and cost-effective procedures while avoiding the use of hazardous materials that are usually utilized as reducing or capping agents. Many biosources, including plants, bacteria, fungus, yeasts, and algae, have been used to fabricate NPs of various shapes and sizes. The authors of this study emphasized the most current studies for fabricating NPs from biosources and their applications in a wide range of fields. This review addressed studies that cover green techniques for synthesizing nanoparticles of Ag, Au, ZnO, CuO, Co3O4, Fe3O4, TiO2, NiO, Al2O3, Cr2O3, Sm2O3, CeO2, La2O3, and Y2O3. Also, their applications were taken under consideration and discussed.

Influence of Fe and Cu Co-Doping on Structural, Magnetic and Electrochemical Properties of CeO2 Nanoparticles.

The nanoparticles of CeO2, Ce0.98Fe0.02O2, and Ce0.78Fe0.02Cu0.20O2 were synthesized using the co-precipitation-synthesis technique. The effect of co-doping of Fe and Cu on structural, optical, and magnetic properties as well as specific capacitance have been studied using X-ray diffraction (XRD), scanning-electron microscopy (SEM), UV-visible spectroscopy, Raman spectroscopy, dc magnetization, and electrochemical measurements at room temperature. The results of the XRD analysis infer that all the samples have a single-phase nature and exclude the formation of any extra phase. Particle size has been found to reduce as a result of doping and co-doping. The smallest particle size was obtained to be 5.59 nm for Ce0.78Fe0.02Cu0.20O2. The particles show a spherical-shape morphology. Raman active modes, corresponding to CeO2, were observed in the Raman spectra, with noticeable shifting with doping and co-doping indicating the presence of defect states. The bandgap, calculated using UV-Vis spectroscopy, showed relatively low bandgap energy (1.7 eV). The dc magnetization results indicate the enhancement of the magnetic moment in the samples, with doping and co-doping. The highest value of saturation magnetization (1.3 × 10−2 emu/g) has been found for Ce0.78Fe0.02Cu0.20O2 nanoparticles. The electrochemical behavior studied using cyclic-voltammetry (CV) measurements showed that the Ce0.98Fe0.02O2 electrode exhibits superior-specific capacitance (~532 F g−1) along with capacitance retention of ~94% for 1000 cycles.

CeO2-Zn Nanocomposite Induced Superoxide, Autophagy and a Non-Apoptotic Mode of Cell Death in Human Umbilical-Vein-Derived Endothelial (HUVE) Cells.

In this study, a nanocomposite of cerium oxide-zinc (CeO2-Zn; 26 ± 11 nm) based on the antioxidant rare-earth cerium oxide (CeO2) nanoparticles (NPs) with the modifier zinc (Zn) was synthesized by sintering method and characterized. Its bio-response was examined in human umbilical-vein-derived endothelial (HUVE) cells to get insight into the components of vascular system. While NPs of CeO2 did not significantly alter cell viability up to a concentration of 200 µg/mL for a 24 h exposure, 154 ± 6 µg/mL of nanocomposite CeO2-Zn induced 50% cytotoxicity. Mechanism of cytotoxicity occurring due to nanocomposite by its Zn content was compared by choosing NPs of ZnO, possibly the closest nanoparticulate form of Zn. ZnO NPs lead to the induction of higher reactive oxygen species (ROS) (DCF-fluorescence), steeper depletion in antioxidant glutathione (GSH) and a greater loss of mitochondrial membrane potential (MMP) as compared to that induced by CeO2-Zn nanocomposite. Nanocomposite of CeO2-Zn, on the other hand, lead to significant higher induction of superoxide radical (O2•−, DHE fluorescence), nitric oxide (NO, determined by DAR-2 imaging and Griess reagent) and autophagic vesicles (determined by Lysotracker and monodansylcadeverine probes) as compared to that caused by ZnO NP treatment. Moreover, analysis after triple staining (by annexin V-FITC, PI, and Hoechst) conducted at their respective IC50s revealed an apoptosis mode of cell death due to ZnO NPs, whereas CeO2-Zn nanocomposite induced a mechanism of cell death that was significantly different from apoptosis. Our findings on advanced biomarkers such as autophagy and mode of cell death suggested the CeO2-Zn nanocomposite might behave as independent nanostructure from its constituent ones. Since nanocomposites can behave independently of their constituent NPs/elements, by creating nanocomposites, NP versatility can be increased manifold by just manipulating existing NPs. Moreover, data in this study can furnish early mechanistic insight about the potential damage that could occur in the integrity of vascular systems.

MnII/III and CeIII/IV Units Supported on an Octahedral Molecular Nanoparticle of CeO2.

The preparation of three new heterometallic clusters [Ce6Mn12O17(O2CPh)26] (1), [Ce10Mn14O24(O2CPh)32] (2), and [Ce23Mn20O48(OH)2(tbb)46(H2O)4](NO3)2 (3; tbb- = 4-tBu-benzoate) is reported. They all possess unprecedented structures with a common feature being the presence of an octahedral CeIV-oxo core: a Ce6 in 1, two edge-fused Ce6 giving a Ce10 bioctahedron in 2, or a larger Ce19 octahedron in 3. Complex 1 is the first Ce6 cluster with a central μ6-O2-. 2 and the cation of 3 are molecular nanoparticles of CeO2 (ceria) because they possess the fluorite structure of bulk ceria and are thus ultrasmall ceria nanoparticles in molecular form. The {Ce19O32} octahedral subunit of the cation of 3 had been predicted from density functional theory studies to be one of the stable fragments of the CeO2 lattice, but has never been previously synthesized in molecular chemistry. Around the Ce/O core of 1-3 is an incomplete monolayer of Mnn ions disposed as four Mn3, two Mn7, and four Mn5 units, respectively. This represents a clear structural similarity with composite (phase-separated) CeO2/MnOx mixtures where at high Ce:Mn ratios the Mn atoms segregate on the surface of CeO2 phases. Variable-temperature dc and ac magnetic susceptibility studies have revealed S = 2, S = 1/2, and S = 3/2 ground states for 1-3, respectively. Fitting of the 5.0-300 K dc data for 1 to a two-J model for an asymmetrical V-shaped Mn3 unit with no interaction between the end MnIII ions gave an excellent fit with the following values: J1 = 5.2(3) cm-1, J2 = -7.4(3) cm-1, and g = 1.96(2).

Green Synthesis of Ceria Nanoparticles Using Azadirachta Indica Plant Extract: Characterization, Gas Sensing and Antibacterial Studies

In the present investigation we have fabricated the cerium dioxide (CeO2) nanoparticles by green route. While preparing the cerium dioxide nanoparticles by co-precipitation method, Neem leaf extract mixed into the precursor of cerium. The synthesized nanoparticles of CeO2 were used for the preparation of thick film sensor by using screen printing strategy. The fabricated CeO2 sensor was characterized by XRD, SEM, EDS and TEM techniques. The structural characteristics investigated by x-ray diffraction technique (XRD). XRD confirms the formation of cubic lattice of CeO2 material. The surface, texture, porosity characteristics were investigated from SEM analysis, while chemical composition of the material was analysed by EDS technique. The transmission electron microscopy (TEM) confirms the formation cubic lattice of the cerium dioxide material. The thickness of the films was calculated from mass difference method, the prepared film sensors belong to thick region. The fabricated material CeO2 sensor was applied as gas sensor to sense the gases such as LPG, petrol vapors (PV), toluene vapors (TV) and CO2. The CeO2 sensor showed excellent gas response for LPG and PV, nearly 93.20 % and 78.23 % gas response. The rapid response and recovery of the prepared sensors was observed at the tested gases. CeO2 material also employed for antibacterial study at several pathogenic organism such as pseudomonas, staphylococcus aureus and salmonella typhae. From antibacterial study it was observed that the material is capable of inhibiting the growth of these pathogenic microbes.

Electrical and magnetic properties of nanostructured Ni doped CeO2 for optoelectronic applications

Employing hydrothermal technique, undoped and nickel doped cerium oxide nanoparticles (Ni doped CeO2 NPs) are synthesized with different concentration of dopant (5 M%, 10 M% and 15 M%). Prepared samples are subjected to Powder X-ray diffraction (PXRD), Scanning electron microscopy (SEM), Energy dispersive X-ray spectroscopy (EDX), High resolution transmission electron microscopy (HRTEM) with selected area electron diffraction (SAED), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), Ultraviolet–visible spectroscopy (UV–vis), Photoluminescence spectroscopy (PL), Vibrational sample magnetometry (VSM), Dielectric and electrical conductivity studies. Formation of CeO2 NPs and Ni doped CeO2 NPs is confirmed by PXRD and EDX. The crystallite size of the samples, determined from powder XRD using Williamson-Hall (W–H) plot, diminishes with increased Ni doping. The lattice parameter variation indicates an initial lattice contraction when the doping is less and a lattice expansion with enhanced Ni doping. These variations in crystallite size and lattice parameter could be due to the replacement of Ce ions by Ni ions in the CeO2 lattice. SEM and HRTEM images show that the morphology of the NPs formed is nearly spherical. The UV–vis spectroscopic studies indicated that bandgap energy of Ni doped CeO2 NPs widens as the Ni dopant concentration is increased. Increase of oxygen vacancy (VO) with increase in Ni concentration is designated by Raman spectra. The PL studies show that the nanoparticles of CeO2 and Ni doped CeO2 exhibit luminescence in the violet-blue-green wavelengths region (400 nm–500 nm). The decrease in emission intensity with increase of Ni concentration is indicative to increase of oxygen vacancies with increase in Ni content which act as non-radiative centers. VSM studies show that all the samples exhibit paramagnetism. The saturation magnetization and the retentivity of the samples increase as the Ni dopant concentration increases. All the samples display frequency dependent dielectric properties. With increase in the concentration of Ni dopant and frequency, a reduction in the values of dielectric constant and dielectric loss and an improvement in the electrical conductivity were observed for all the samples.

Truly Monodisperse Molecular Nanoparticles of Cerium Dioxide of 2.4 nm dimensions: A {Ce100 O167 } Cluster.

Ultra-small nanoparticles of CeO2 obtained in molecular form, so-called molecular nanoparticles, have been limited to date to a family whose largest member is of nuclearity Ce40 with a {Ce40 O58 } core atom count. Herein we report that a synthetic procedure has been developed to the cation [Ce100 O149 (OH)18 (O2 CPh)60 (PhCO2 H)12 (H2 O)20 ]16+ , a member with a much higher Ce100 nuclearity and a {Ce100 O167 } core that is more akin to the smallest ceria nanoparticles. Its crystal structure reveals it to possess a 2.4 nm size and high D2d symmetry, and it has also allowed identification of core surface features including facet composition, the presence and location of Ce3+ and H+ (i.e. HO- ) ions, and the binding modes of the ligand monolayer of benzoate, benzoic acid, and water ligands.

Truly Monodisperse Molecular Nanoparticles of Cerium Dioxide of 2.4 nm dimensions: A {Ce100O167} Cluster

AbstractUltra‐small nanoparticles of CeO2 obtained in molecular form, so‐called molecular nanoparticles, have been limited to date to a family whose largest member is of nuclearity Ce40 with a {Ce40O58} core atom count. Herein we report that a synthetic procedure has been developed to the cation [Ce100O149(OH)18(O2CPh)60(PhCO2H)12(H2O)20]16+, a member with a much higher Ce100 nuclearity and a {Ce100O167} core that is more akin to the smallest ceria nanoparticles. Its crystal structure reveals it to possess a 2.4 nm size and high D2d symmetry, and it has also allowed identification of core surface features including facet composition, the presence and location of Ce3+and H+ (i.e. HO−) ions, and the binding modes of the ligand monolayer of benzoate, benzoic acid, and water ligands.

Effects of surface structure and defect behavior on the magnetic, electrical, and photocatalytic properties of Gd-doped CeO2 nanoparticles synthesized by a simple chemical process

Magnetic, electrical, and photocatalytic characteristics of a series of nanoparticles (NPs) of Gd-doped CeO2 (GdxCe1-xO2 (100x% GDC); x = 0.03, 0.05, 0.10, and 0.20) were analyzed in correlation with their surface structure and defect behavior. The GDC NPs were synthesized by a simple chemical process through a polymer-based precursor. X-ray diffraction (XRD) studies confirmed the effective substitution of Gd3+ in the face centered cubic (fcc) lattice of the host matrix of CeO2. The optical band gap (Eg) and oxygen vacancies (VO) increased with Gd-doping as validated by UV–visible reflectance and Raman spectroscopy. Further analysis with X-ray photoelectron spectroscopy (XPS) substantiated the formation of non-stoichiometric CeO2 structure through Ce4+ → Ce3+ reduction to maintain charge neutrality after Gd-doping. Samples of 20% GDC processed at 400 °C, showed the highest saturation magnetization (MS) of 17.58 memu/g at room temperature. A maximum conductivity of 2.11 × 10−3 S/cm was recorded at 650 °C in air in the 20% GDC samples processed at 1100 °C. Using 20% GDC NPs processed at 400 °C, a typical value of apparent degradation rate constant (k) of 2.13 × 10−2 min−1 was obtained for methyl orange (MO) dye under UV–visible irradiation for 10 min.

Strong Adsorption of Arsenite and Phosphate from Aqueous Solution Using La2O3–CeO2 Composite

In the present paper, the synthesis of La2O3–CeO2 composite using the sol–gel combustion method with gelatin as a template and its application for arsenite and phosphate removal are demonstrated. The obtained composite was characterized using thermal analysis (TG–DTA), X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HR-TEM), and energy-dispersive X-ray spectroscopy elemental mapping (EDX-elemental mapping). It is found that the La–Ce bimetallic oxide consists of nanoparticles of La2O3 and CeO2 with a size of around 10–20 nm. The La2O3 and CeO2 particles in the composite are highly dispersed. The adsorption of arsenite and phosphate from aqueous solutions on the La2O3–CeO2 composite was investigated at ambient temperature utilizing a batch technique. The arsenite and phosphate adsorption capacity derived from the Langmuir isotherm is 102.5 and 193.3 mg g−1, respectively, which is higher than those reported in the previous papers. The material does not lose much capacity even after eight cycles. The high capacity for phosphate adsorption at low and high concentrations enables the La2O3–CeO2 composite to become a potential material for water and wastewater treatment.

Synthesis of rare earth metal oxide nanoparticle for simultaneous removal of fluoride and As(III) from aqueous solution

This study aims to investigate the sorption behavior of As(III) in presence of fluoride ion in an aqueous solution. Conventionally the As(III) is removed by converting it to As(V) with certain oxidants followed by sorption or precipitation. Limited information is available for As(III) sorption in presence of fluoride ions. The present study deals with single-step sorption of As(III) in the absence and presence of fluoride ion with rare earth metal oxide as adsorbent. The nanoparticles of CeO2 were synthesized by a low-temperature chemical precipitation method. The CeO2 as adsorbent is tested for sorption of As(III) and fluoride in a single system. The solution pH has a significant role in the sorption of fluoride ion however, negligible effect on As(III) sorption in the pH range of 4–8. The adsorbent showed the significant uptake capacity for arsenic and fluoride even in binary ion systems as 81.9 F mg/g and 3.3 As(III) mg/g respectively. The spent adsorbent is efficiently reused for ion sorption after regeneration and activation.

Surface Modification of Cu-SSZ-13 with CeO2 to Improve the Catalytic Performance for the Selective Catalytic Reduction of NO with NH3

A series of Cu-SSZ-13@CeO2 catalysts with surface modification with CeO2 was prepared by the modified self-resemble method based on the one-pot synthesized Cu-SSZ-13 catalyst and applied for the selective catalytic reduction of NO by NH3. The low-temperature catalytic activity and the tolerance to SO2 + H2O of Cu-SSZ-13@CeO2 were found to enhance markedly compared with Cu-SSZ-13. In parallel, the XRD, N2-BET, H2-TPR, SEM, XPS, and in situ DRIFTS were performed to characterize the catalysts. XRD and SEM results proved that the surface of Cu-SSZ-13 was covered by nanoparticles of CeO2. XPS results further confirmed that Ce species were in the outer of the catalysts. N2-BET indicated that the physical structure parameters of the Cu-SSZ-13@CeO2 were changed obviously due to the coverage of CeO2. H2-TPR suggested that the redox properties of the Cu-SSZ-13@CeO2 catalysts were improved compared to the unmodified Cu-SSZ-13. In situ DRIFTS results demonstrated that the intensities of the bands attributed to NH3 and NOx species on the surface of Cu-SSZ-13@CeO2-2 enhanced due to the CeO2 modification, which played an important role for the NH3-SCR performance.

Effect of CeO2 Nanoparticles on Interface of Cu/Al2O3 Ceramic Clad Composites.

Cu/Al2O3 ceramic clad composites are widely used in electronic packaging and electrical contacts. However, the conductivity and strength of the interfacial layer are not fit for the demands. So CeO2 nanoparticles 24.3 nm in size, coated on Al2O3 ceramic, promote a novel CeO2–Cu2O–Cu system to improve the interfacial bonded strength. Results show that the atom content of O is increased to approximately 30% with the addition of CeO2 nanoparticles compared with the atom content without CeO2 in the interfacial layer of Cu/Al2O3 ceramic clad composites. CeO2 nanoparticles coated on the surface of Al2O3 ceramics can easily diffuse into the metallic Cu layer. CeO2 nanoparticles can accelerate to form the eutectic liquid of Cu2O–Cu as they have strong functions of storing and releasing O at an Ar pressure of 0.12 MPa. The addition of CeO2 nanoparticles is beneficial for promoting the bonded strength of the Cu/Al2O3 ceramic clad composites. The bonded strength of the interface coated with nanoparticles of CeO2 is increased to 20.8% compared with that without CeO2; moreover, the electric conductivity on the side of metallic Cu is 95% IACS. The study is of great significance for improving properties of Cu/Al2O3 ceramic clad composites.

Exergy and energy amelioration for parabolic trough collector using mono and hybrid nanofluids

Energy and exergy efficiency amelioration of the parabolic trough has taken high interest since recent years, especially when nanofluid used as an enhancement category. This paper aimed to improve LS-2 parabolic trough model and compare the enhancement effect that occurred using different mono and hybrid nanofluids. Inserting mono nanoparticles of Al2O3, CeO2, CuO, and hybrid combinations of Al2O3 with CeO2, or CuO nanoparticles in a Syltherm 800 was investigated by five different cases. The investigation was presented under total volume fraction 4% for all nanofluids and mixing fraction 50:50 for the hybrid types in order to facilitate the analysis and compare various results at the same conditions. Those cases and their comparisons were solved using MATLAB Symbolic tools under turbulent flow regime and variable inlet temperature to present wide domain behavior for the energy and exergy efficiency, Nusselt number, heat transfer coefficient, and pressure drop, whereas the analytical solution of the energy balance equation was taken from the literature and improved to cover the mentioned cases. Moreover, the results were compared with previous researches that used different thermal fluid and showed high accuracy behavior with low deviation. Therefore, the findings showed that Al2O3 and CeO2 hybrid nanofluids were more efficient than using of both Al2O3 and CuO hybrid nanofluids and any mono nanofluids contain the same nanoparticles. The maximum enhancement of thermal and exergy efficiency of using Al2O3 and CeO2 hybrid nanofluids was 1.09% and 1.03%, respectively, whereas it was enhanced by 167.8% and 200.7% for the Nusselt number and heat transfer coefficient, respectively. Also, the hybrid nanofluids have higher advantage over the mono nanofluids by presenting lower pressure drop values. Finally, the assessment of efficiency variation affected by thermal properties of the nanoparticle was presented under optimum temperature equal to 575 K.