Cerium Oxide

The surface exchange and bulk transport of oxygen are highly relevant to ceria-based redox materials, which are envisaged for the solar thermochemical splitting of carbon dioxide in the future. Experimental investigations of oxygen isotope exchange on CeO2-δ, Ce0.9M3+0.1O1.95-δ (with M3+ = Y, Sm) and Ce0.9M4+0.1O2-δ (with M4+ = Zr) samples were carried out for the first time utilizing oxygen-isotope-enriched C18O2 gas atmospheres as the tracer source, followed by Secondary Ion Mass Spectrometry (SIMS), at the temperature range 300 ≤ T ≤ 800 °C. The experimental K˜O and D˜O data reveal promising results in terms of CO2 splitting when trivalent (especially Sm)-doped ceria is employed. The reaction temperatures are lower than previously proposed/reported due to the weak temperature dependency of the parameters K˜O and D˜O. The majority of isotope exchange experiments show higher values of K˜O and D˜O for Sm-doped cerium dioxide in comparison to Y-doped and Zr-doped ceria, as well as no...

In recent years, remarkable progress has been made in developing nanotechnology. This has led to a fast-growth of commercial applications, which involve the use of a great variety of manufactured nanomaterials. Given that, soils and sediments are the ultimate sinks of engineered nanomaterials (ENMs), they can be taken up by microorganisms, nematodes, earthworms or plants, and potentially transferred to the food chain up to animals and humans. However, the reactions of the biota exposed to ENMs of different size are still not well understood. Very few studies on nanoparticles-plant interactions have been published, so far. In this paper we report the results of multiple experiments carried out to study the effects of cerium oxide nanoparticles (nCeO2) on Hordeum vulgare. The nCeO2 powder and suspension were characterised for specific surface area, z-average size, and zeta potential. Germinating caryopses and barley seedlings were exposed to an aqueous dispersion of nCeO2 at respectiv...

Zinc-doped cerium oxide nanoparticles (Zn-doped CeO 2 -NPs) with Ce 1-x Zn x O 2 composition, where x equals to 0.0, 0.01, 0.03, and 0.05 are synthesized through a green based sol-gel method from nitrate precursors and gelatin at the fixed calcination temperature of 600 °C maintained for 2 h. The powder X-ray diffraction (PXRD) patterns displayed the single-crystalline structure of these particular samples, which seemed to be completely indexed with the cubic fluorite phase. The evolution of crystalline phases in Ce 1-x Zn x O 2 are assured by the observed broadening in PXRD peaks, while the field emission scanning electron microscopy (FE-SEM) images revealed that the sphericalshaped single-crystalline NPs do exist and confirmed the size estimations that were obtained from the Scherrer's equation. A dose dependent toxicity with non-toxic effects of concentrations up to 31.25 μg/mL is illustrated through the In vitro cytotoxicity studies regarding Neuro2A cells.

MnOx-CeO2 catalysts (molar ratio Mn/Ce 1) were prepared using two methods: co-precipitation and citrate methods. The prepared solids were calcined at 500°C, and characterized by XRD, nitrogen adsorption-desorption technique and SEM morphological, they were, then, tested in the toluene combustion reaction. The catalytic performances of the prepared solids were evaluated in the temperature range 150-400°C. The XRD analysis of the two solids showed that the only crystalline phase detected is cerium oxide. BET surface area measurements showed that the incorporation of manganese led to an increase in the specific surface area of ceria, the solid prepared by the co-precipitation method led to the highest specific surface area (156 m²/g). The solids showed good performances in the toluene combustion reaction that depend strongly on the preparation method. The best catalytic activity was obtained for the catalyst prepared by the citrate method achieving a complete conversion of toluene at 250 ° C.

Cerium oxide nanoparticles (CeO2 NP) are a common component of many commercial products. Due to the general concerns over the potential toxicity of engineered nanoparticles (ENPs), the phytotoxicity and in planta accumulation of CeO2 NPs have been broadly investigated. However, most previous studies were conducted in hydroponic systems and with grain crops. For a few studies performed with soil grown plants, the impact of soil properties on the fate and transport of CeO2 NPs was generally ignored even though numerous previous studies indicate that soil properties play a critical role in the fate and transport of environmental pollutants. The objectives of this study were to evaluate the soil fractionation and bioavailability of CeO2 NPs to Raphanus sativus L (radish) in two soil types. Our results showed that the silty loam contained slightly higher exchangeable fraction (F1) of cerium element than did loamy sand soil, but significantly lower reducible (F2) and oxidizable (F3) fract...

Crystalline cerium (iv) hydrogen phosphate Ce(HPO 4 ) 2 .1.33H 2 O(CeP), and nano particles zirconium oxide(nZrO 2 ), of average size19.3nm, were prepared and characterized by chemical , XRD, FT-IR and TGA analysis. Mixing slurry aqueous solution of nZrO 2 and CeP in 25:75 wt/wt% mixing ratios, respectively, lead to formation of novel zirconium oxide-crystalline cerium phosphate nanocomposite, polybenzimidazole-, polyaniline-, polyindole-, and polycarbazole nanocomposites were prepared via in-situ chemical oxidation of their parent monomers. A possible explanation is part of CeP, in inorganic composite (nZrO 2 -CeP) was attacked by the parent monomers converted to cerium(III) orthophosphate(CePO 4 ). The resultant nanocomposites were characterized by elemental (C,H,N) analysis , FT-IR, and scanning electron microscopy(SEM). From elemental (C,H,N) analysis. the amount of % in wt. of organic materials present in (nZrO 2 -CeP) nanocomposites found to be , for [polybenzimidazole(12..56%). polyaniline (16.50%) , polyindole (11.74 %), and polycarbazole (13.99 %)]. Electrical conductivity for resultant conducting polymers were investigated using DMSO solvent found to be in the range of semiconductors.

A novel cerium loaded zinc oxide was successfully synthesized by a precipitation-decomposition method and calcination at 400 1C for 12 h. The catalyst was characterized by X-ray diffraction (XRD), high resolution scanning electron microscopy (HR-SEM), energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), diffuse reflectance spectroscopy (DRS), photoluminescence (PL) and Brunauer-Emmett-Teller (BET) surface area measurements. The photocatalytic activity of Ce-ZnO was investigated for the degradation of AR 27 under solar light. It is found to be more efficient than bare zinc oxide (ZnO), titanium dioxide-P25 (TiO 2 -P25) and TiO 2 (Merck) at pH 12 for the mineralization of AR 27. The effects of operational parameters have been analyzed, and the mineralization of AR 27 has been confirmed by chemical oxygem demand (COD) measurements. The catalyst is found to be reusable. A mechanism has been proposed for the degradation of AR 27 by Ce-ZnO under solar light illumination.

Ternary oxides have been used as effective photocatalyst for carrying out number of chemical reactions. Method of preparation has major effect on the performance of these mixed oxide catalysts. In the present work, cerium iron oxide catalyst was synthesized using co-precipitation method and specific heating cycle. Synthesized catalyst was characterized using X-ray diffraction patterns. Photocatalytic degradation on gentian violet dye was observed using this catalyst and progress of the reaction was monitored spectrophotometrically. The effect of variation of different parameters like concentration of gentian violet, pH, amount of semiconductor and light intensity was also studied. A tentative mechanism for the photocatalytic bleaching of gentian violet has been proposed.

Surface morphology is known to affect catalytic activity, as some surfaces show greater activity than others. One of the key challenges is to identify strategies to enhance the expression of such surfaces and also to prevent their disappearance over time. Here, we apply density functional theory to the catalytic material CeO2 to predict the effect of adsorbed CO2 on the morphology of the material as a function of temperature and pressure. We predict that CO2 adsorbs as surface carbonates and that the magnitude of the adsorption energy is surface dependent, following the order {100} > {110} > {111}. We show that this difference leads to selective thermodynamic enhancement of {100} surfaces as a function of CO2 partial pressure and temperature. Finally, we show how the calculated surface free energies as a function of external conditions can be deployed to predict changes in the equilibrium particle morphology. These include the prediction that ceria nanoparticles prepared in the presence of supercritical CO2 will favour enhanced cube-like morphologies.

The effect of iron-doped cerium oxide (FeCeO 2 ) nanoparticles as a fuel additive was experimentally investigated with waste cooking oil methyl ester (WCOME) in a four-stroke, single cylinder, direct injection diesel engine. The study aimed at the reduction of harmful emissions of diesel engines including oxides of nitrogen (NO x ) and soot. Two types of nanoparticles were used: cerium oxide doped with 10% iron and cerium oxide doped with 20% iron, to further investigate the influence of the doping level on the nanoparticle activity. The nanoparticles were dispersed in the tested fuels at a dosage of 90 ppm with the aid of an ultrasonic homogenizer. Tests were conducted at a constant engine speed of 2000 rpm and varying loads (from 0 to 12 N.m) with neat diesel (D100) and biodiesel-diesel blends of 30% WCOME and 70% diesel by volume (B30). The engine combustion, performance, and emission characteristics for the fuel blends with nanoparticles were compared with neat diesel as the base fuel. The test results showed improvement in the peak cylinder pressure by approximately 3.5% with addition of nanoparticles to the fuel. A reduction in NO x emissions by up to 15.7% were recorded, while there was no noticeable change in unburned hydrocarbon (HC) emissions. Carbon monoxide (CO) emission was reduced by up to 24.6% for B30 and 15.4% for B30 with nano-additives. Better engine performance was recorded for B30 with 20% FeCeO 2 as compared to 10% FeCeO 2 , in regard to cylinder pressure and emissions. The brake specific fuel consumption was lower for the fuel blend of B30 with 10% FeCeO 2 nanoparticles, in low-to-medium loads and comparable to D100 at high loads. Hence, a higher brake thermal efficiency was recorded for the blend in low-to-medium loads compared to D100.

Studies have been developed in last decades in order to produce NiO-based material to be used as anode in solid oxide fuel cell (SOFC). Aqueous-based tape casting was used to produce NiO-GDC substrates with smooth and homogeneous surfaces and good flexibility. Physical and mechanical properties were obtained in green tapes sintered at temperatures ranging from 1200 to 1400 ͦ C. The tapes sintered in 1400 ͦ C showed the best density and porosity values and mechanical strength between 7 and 25 MPa. SEM micrographs show a dense material with cracks and pores. The sintered material shows the presence of nickel oxide and gadolinium cerium oxide.

Catalytic decomposition of N 2 O over calcined Co-Mn-Al layered double hydroxide (LDH) modified with slight amount of alkali (Li, Na, K), rare earth (La, Ce), or noble metals (Pd, Pt) was studied. Two methods of promoter addition were applied: impregnation of LDH-related Co-Mn-Al mixed oxide by a promotercontaining solution and incorporation of the promoter during coprecipitation of the LDH precursor. The method of preparation affected the reducibility of the obtained mixed oxide catalysts but its effect on the surface area (with the exception of a cerium-contained sample) and N 2 O conversion was less evident. The modification of the Co-Mn-Al mixed oxide with K or Na increased N 2 O conversion, while no effect or a decrease in the N 2 O conversion was observed over the other examined catalysts. Alkali metals act as electron promoters; therefore, the differences in catalytic activity may be related to changes of oxygentransition metal bond strength. The Co-Mn-Al mixed oxides with 1.8 wt% K exhibited a high catalytic activity even under the simultaneous presence of O 2 , H 2 O and NO x . The laboratory stability test revealed maintenance of the beneficial effect for 360 h.

Bio-motivated CeO 2 NPs were fabricated using plant extract of Cleome simplicifolia. The chemicals present in the plant extracts played pivotal role in the fabrication of CeO 2 NPs. Initially, fabricated CeO 2 nanoparticles were authenticate by using the XRD pattern which resembles a cubic structure. UV-Visible data estimated the band gap of CeO 2 around 3.50 eV. SEM images revealed nearly monodisperse spherical shapes due to agglomerization of CeO 2 NPs. DPPH assay of CeO 2 NPs exhibited an excellent antioxidant property. Moreover, molecular docking of CeO 2 NPs was investigated by new protein molecule.

Reactive oxygen species (ROS) have been linked to cellular degeneration, irreversible DNA damage, and various diseases. Cerium oxide nanoparticles have shown promising medical applications for their SOD mimetic activity to catalyze the breakdown of various ROS. Increasing the biocompatibility, longevity of residence, and rate of internalization of nanoceria are essential to increase its range of biomedical applications. Polyethylene glycol's (PEG) hydrophilic, nonimmunogenic, and antioxidative properties make it an ideal coating for increasing cerium nanoparticle's applicability. Gelatin's low cost and versatility have made it widely employed as an antioxidant drug carrier in a variety of physiological systems. Because of gelatin's susceptibility to ROS denaturation and well-researched structure, it is a useful tool for assessing conformational damage in applications that involve acute oxidative stress. PEG-nanoceria of various molar weights was synthesized from Ce (III) nitrate and incorporated into gelatin hydrogels that were exposed to hydrogen peroxide to provide oxidative stress damage. This study aims to assess changes to gelatin conformation were assessed using Fourier transform infrared spectroscopy. PEG-Nanoceria showed radical damage mitigation in hydrogels as evident by the decreased change in transmittance over its non-PEG counterpart. There was notably exceptional damage mitigation in the amide A and amide II regions. These promising findings suggest more research should be done to examine polymer-coated nanoceria's antioxidative properties in more biologically relevant models.

Cerium oxide nanoparticles were continuously precipitated from a solution of cerium(III) nitrate and ammonium hydroxide using a static microchannel T-mixer. Tmixer synthesis results were compared with synthesis results from batch precipitation. Findings show that the method of mixing is important in the ceria precipitation process. Uniform porous film structures and nanorods were produced when the particle chemistry was synthesized using T-mixing followed by spin coating. Batch mixing, when using higher NH 4 OH feed concentrations followed by spin coating, was characterized by the heavy agglomeration of nanoparticles. Similar, high aspect ratio nanorods were produced when feed conditions in both batch mixing and T-mixing were identical demonstrating that the momentum effects of continuous microchannel T-mixing did not impact the synthesis process. In addition, it was found that the micromixing approach reduced the exposure of the Ce(OH) 3 precipitates to oxygen, yielding hydroxide precipitates in place of CeO 2 precipitates. The key advantage of the micro-scale T-mixing approach is higher throughput which is important for the scaling of ceria nanoparticle production.

A new approach to recover and purify cerium oxide from the spent autocatalyst after cordierite substrate dissolution and catalytic metals separation has been investigated. Cerium oxide was converted to Ce(IV) sulfate by baking with concentrated H 2 SO 4 at 250 °C, and ∼95% product could be subsequently dissolved in 1.0 M H 2 SO 4 solution at 75 °C and 5% pulp density in 180 min. At the optimal conditions (molar ratio of cerium/oxalic acid of 1:15 at 25 °C and 120 min), ∼98% Ce(IV) in the obtained solution was precipitated as Ce(III) oxalate deca-hydrate, which was calcined at 550 °C to produce cerium oxide of high purity (∼99.9%). The transformation of cerium oxide during the recovery process using acid baking, oxalate precipitation, and calcination was examined by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analysis, which provided necessary information on different phases and oxidation states of cerium. The recovery of cerium oxide is the last stage of the "zero-waste" process based on the substrate dissolution by which it is possible to recycle all the valuable components from the spent autocatalyst.

Present work portrays the surface morphology dependent electrochemical behaviors tuned by annealing the chemical bath deposited (CBD) cerium oxide electrodes. The altered nanostructure properties are well-supported by in-depth structural and morphological analysis. Cerium oxide electrode annealed at 200 °C exhibits good surface properties enabling maximum electro-active porous cavities to penetrate electrolyte ions towards enhanced electron transfer. Consequently, the electrode exhibits maximum specific capacitance of 750 F/g with remarkably stable charge-discharge cycles. Fabricated symmetric solid-state supercapacitor device impressively expands potential window to 1.2 V with the aid of PVA-LiClO 4 gel electrolyte with a peak specific capacitance of 321.3 F/g with top-up of 61.4 Wh/kg specific energy. The series combination of two devices confirms the strong energy storage ability by glowing 'VNIT' acronym designed through 21 red LEDs from the practical point of view.

This supporting information contains a total of nine pages, including the materials preparation procedure, description of characterization techniques, Two tables: • Chemical Formulae for different HT compounds. • Chemical composition determined by EDX technique.

We investigated the effects of the Gibbs free energy difference (ΔG o ) and distribution of oxygen vacancies in a bilayer ZnO/ZrO 2 structure. The device exhibited high endurance characteristics of up to 1000 DC repetitive resistive cycles, long retention (10 4 ), and a low coefficient of variation of SET and RESET-voltages (6% and 5%, respectively). In addition, X-ray photoelectron spectroscopy (XPS) analysis of the ZnO and ZrO 2 layers indicated that the oxygen vacancies/defects in the ZnO layer (44.13%) were larger than in the ZrO 2 layer (34.11%), and that the oxygen ions of OeZr (65.89%) were larger than those of OeZn (55.87). This XPS analysis confirmed that the differing oxygen vacancy distributions in the ZnO/ZrO 2 layer are responsible for improving the switching performance. The switching behavior, endurance, and retention time strongly depend on the types of electrode and switching materials used. We obtained qualitative and quantitative evidence that ΔG o of the oxide materials plays a significant role in determining the resistive switching characteristics. Bipolar switching mechanisms are explained by considering ΔG o in the ZnO and ZrO 2 layers, where the formation and rupture of conductive filaments are caused by oxygen vacancies. Our findings suggest that a bilayer ZnO/ZrO 2 structure is promising for application to non-volatile memory.

Current research involves preparing cerium oxide nanoparticles using simple, environmental-friendly green synthesis approach via fresh green tea leaf extract (Camellia sinensis) as a capping and reducing agent, Ultraviolet-visible spectroscopy (UV-Vis.) is used to check the formation of nanoparticles by investigate the absorption peak and energy gap (E g ); Maximum absorption peak was around 295nm and E g was 4.2eV calculated using Planck's equation, X-Ray diffraction (XRD) analysis of Nano powder stated that Cerium Oxide has a cubic fluorite structure with face centered cubic (FCC) structure, blood serum glucose levels, liver functions after CeO 2 Nanoparticles treatment for rats were reported in this paper. Forty eight adult male rats were used and divided randomly into six groups each group has eight rats (n=8), Results stated that blood glucose levels, liver enzymes were increased in groups that injected by dexamethasone while considerably modified in rats administered by Cerium Oxide Nanoparticles.

Current research involves preparing cerium oxide nanoparticles using simple, environmental- friendly green synthesis approach via fresh green tea leaf extract (Camellia sinensis) as a capping and reducing agent, Ultraviolet-visible spectroscopy (UV-Vis.) is used to check the formation of nanoparticles by investigate the absorption peak and energy gap (Eg); Maximum absorption peak was around 295nm and Eg was 4.2eV calculated using Planck’s equation, X-Ray diffraction (XRD) analysis of Nano powder stated that Cerium Oxide has a cubic fluorite structure with face centered cubic (FCC) structure, blood serum glucose levels, liver functions after CeO2 Nanoparticles treatment for rats were reported in this paper. Forty eight adult male rats were used and divided randomly into six groups each group has eight rats (n=8), Results stated that blood glucose levels, liver enzymes were increased in groups that injected by dexamethasone while considerably modified in rats administered by Cerium Ox...

Cerium oxide is an interesting mixed valence compound of great technological importance. We model the growth of thin films of this substance by describing the statistical nucleation of atomic units containing Ce 3+ and Ce 4+ . The theoretical results are compared with available experimental values of the magnetic susceptibility of the material, which is related to the proportion of magnetic atoms in the solid. The model is able to predict the composition of the final solid under different preparation conditions, namely the oxygen content of the precursor and the temperature of the substrate.

Here, we explored the effects of nanoceria on neural progenitor cells using the C17.2 murine cell line as a model. First, we assessed the effects of nanoceria versus samarium (Sm) doped nanoceria on cell viability in the presence of the prooxidant, DMNQ. Both particles were taken up by cells and nanoceria, but not Sm-doped nanoceria, elicited a temporary cytoprotective effect upon exposure to DMNQ. Next, we employed RNA sequencing to explore the transcriptional responses induced by nanoceria or Sm-doped nanoceria during neuronal differentiation. Detailed computational analyses showed that nanoceria altered pathways and networks relevant for neuronal development, leading us to hypothesize that nanoceria inhibits neuronal differentiation, and that nanoceria and Smdoped nanoceria both interfere with cytoskeletal organization. We confirmed that nanoceria reduced neuron specific β3-tubulin expression, a marker of neuronal differentiation, and GFAP, a neuroglial marker. Furthermore, using super-resolution microscopy approaches, we could show that both particles interfered with cytoskeletal organization and altered the structure of neural growth cones. Taken together, these results reveal that nanoceria may impact on neuronal differentiation, suggesting that nanoceria could pose a developmental neurotoxicity hazard.

Non-reactive rf magnetron sputtering was used to deposit CeO 2 and Sn-CeO 2 thin films on Si(1 0 0) wafer substrates. CeO 2 sputtering was performed using a pure CeO 2 target (Kurt J. Lesker Company, 99.99% purity) at a distance of 90 mm from the Si substrate (Si wafer covered by natural oxide layer) with rf power of

In the present work antibacterial effect of NCO (Nano-Cerium Oxide) particles on E.Coli (Escherichia Coli) Bacteria was studied. NCO (Nano Cerium Oxide) particles were synthesized via microwave induced combustion method. XRD (X-Ray Diffraction), SEM (Scanning Electron Microscope) and FTIR (Fourier Transform Infrared Spectroscopy) characterized. NCO particles. Using Scherrer equation it was noted that NCO particles of 14-25 nm size were produced. The SEM and XRD results showed that size of NCO particles was decreased with increasing synthesization time. Synthesization time played vital role on the size of NCO particles. It was also noted that antibacterial action of NCO particles is size dependent. Antibacterial study through disc diffusion method revealed that NCO particles enhanced the efficiency of Amikin Grasil, Terivid and spraxin drugs against the E.Coli bacteria appreciably.

Overproduction of free radicals contributes to oxidative stress and inflammation leading to various disease conditions. Cerium oxide nanoparticles (nanoceria) have been shown to scavenge free radicals and have the potential for being used as a therapeutic agent in disease conditions. Therefore, in the present study, human monocytic leukemia cells (THP-1) were used as a model to evaluate the uptake and free radical scavenging activity of nanoceria. Our data showed a significant (<0.05) increase in the internalization of nanoceria in a concentration-dependent (10-100 µg/mL) manner in THP-1 cells. Although no cytotoxicity was observed at these concentrations, nanoceria significantly (<0.05) reduced the amount of reactive oxygen species. This was evident by a significant (<0.05) decrease in the 2,7-dichlorofluorescein diacetate fluorescence observed in flow cytometry and fluorescence microscopy. The present study shows that nanoceria have therapeutic potential in diseases such ...

Studies have been developed in last decades in order to produce NiO-based material to be used as anode in solid oxide fuel cell (SOFC). Aqueous-based tape casting was used to produce NiO-GDC substrates with smooth and homogeneous surfaces and good flexibility. Physical and mechanical properties were obtained in green tapes sintered at temperatures ranging from 1200 to 1400 ͦ C. The tapes sintered in 1400 ͦ C showed the best density and porosity values and mechanical strength between 7 and 25 MPa. SEM micrographs show a dense material with cracks and pores. The sintered material shows the presence of nickel oxide and gadolinium cerium oxide.

A high-throughput flame spray pyrolysis directly affords lowloading Pt catalyst supported on cerium oxide, which is an excellent material for selective semihydrogenation of C2H2 at 180 C, exhibiting nearly complete conversion of C2H2 (98.2%) with high selectivity towards C2H4 (87.1%). Pt in this catalyst is atomically dispersed within cerium oxide, and this structural feature restricts C2H4 adsorption as π-bonded, known to promote C2H4 selectivity. Partial hydrogenation of C2H2 is an important industrial process for converting traces of C2H2 in the C2H4 product stream from naphtha cracker to C2H4 (C2H2 +H2  C2H4), otherwise C2H2 will poison the Ziegler-Natta catalyst during olefin polymerization. An industrial catalyst for this reaction is PdAg/Al2O3 with typical Pd weight loadings of 0.03%, 1 which unfortunately deactivates with time due to the formation of subsurface H in the form of -PdH hydride and coke build-up on active Pd sites. 2 Using smaller Pd clusters and bimetallic systems provides a useful strategy for overcoming these drawbacks. Small Pd sizes shift the metal d-band center downward relative to the Fermi level (EF), which weakens the adsorption of C2H4, and thus facilitates C2H4 turnover preventing undesired subsequent hydrogenation of C2H4 to C2H6. 3 Alloying of Pd with metals, such as Ag, Ga, Au, Cu, Zn, renders the active Pd sites spatially isolated, which prevents coking while increasing the selectivity towards C2H4 via a site-isolation concept. Reducing catalyst acidity is another approach to tackle its deactivation (fouling), resulting from the formation of green oil and carbonaceous deposits. Recently, we embarked on the investigation of catalysts for partial hydrogenation of C2H2. Initially, we were interested in understanding the behavior of Pd catalysts using combined

In the present study, the physical characteristics of jatropha methyl ester (JME) and tyre pyrolysis oil (TPO) have been evaluated. TPO possess high calorific value and a low cetane number, while JME has a high cetane number and average calorific value, as compared to diesel. So, blends of JME and TPO have been made and mixed with cerium oxide nanomaterial for controlling harmful emissions. Experimental analysis was carried out in a diesel engine with JMETPOCeO 2 blends and it was found that JME80TPO20CeO 2 (JME 80% and TPO 20% by volume mixed with 1 ppm of CeO 2 nanomaterial) blend has a thermal efficiency of 24.25%, which is quite comparable with that of diesel. Also, an appreciable decrement in carbon monoxide emission, of 43.11% with respect to diesel, was found.

This work aimed to study the preparation of cerium oxide (CeO2) used as the catalyst for biodiesel production from palm oil. The precipitation method was used in the catalyst synthesis. The effects of oxalic concentrations and stirring rates in the precipitation process were investigated. Oxalic acid was added into cerium (Ce) in ethylenediaminetetraacetic acid solution to form Ce oxalate before the Ce oxalate was calcined to obtain CeO2. The results showed that oxalic concentrations and stirring rates slightly affect the morphology of CeO2. However, these parameters considerably affect the amount of basic sites of CeO2. The basicity of CeO2 plays the main role in catalyzing the transesterification reaction for biodiesel production. When CeO2 was used as the catalyst in biodiesel production from palm oil under operating conditions using a 5% catalyst, methanol-to-oil molar ratio of 30:1, reaction temperature of 150°C, 13.8 bars, and 3-h reaction time, CeO2 obtained from 3% oxalic co...

In this paper we use XPS to study the interaction of Ce overlayers with the semiconductor GaSb 111 surface and Ž . Ce-promoted oxidation of the substrate. The results show that when cerium deposits on GaSb 111 , it forms weak bonds of Ce-Ga and Ce-Sb with the substrate and makes Ga atoms diffuse out. A Ce-Ga intermetallic phase is formed on the surface. When the exposure of O reaches 50 L, the oxide of cerium, Ce O , begins to change into unstable CeO . The 2 2 3 2 dissociation of CeO results in obvious oxidation of the substrate. The main products are Ga O , Sb O and then Sb O . 2 2 3 2 3 2 5 After annealing at 250 and 4008C, respectively, some of the oxygen atoms transfer from cerium dioxide toward Ga and Sb in the substrate, by which it strongly promotes the oxidation of the substrate. q 1997 Elsevier Science B.V.

BACKGROUND: Cerium oxide is the oxide form of cerium, which has protective effects in ischemia reperfusion (I/R) injury. The purpose of our study was to look into the effects of this rare-earth metal on erythrocyte deformability in rat lower extremity I/R injury model. MATERIALS AND METHODS: We used 24 Wistar albino rats as subjects in our study. They were divided into 4 groups; randomized control group (group C; n = 6), cerium oxide group 0.5 mg.kg-1 , intraperitoneal (group CO; n = 6), I/R group (group I/R; n = 6) and I/R group with cerium oxide 0.5 mg.kg-1 intraperitoneally (group I/R-CO; n = 6). Erythrocyte packs were prepared from heparinized blood samples and deformability measurements were performed. RESULTS: We obtained similar results from the control and I/R-CO groups (p = 0.158). The results in I/R group were evidently higher than those of the control, CO, and IR-CO groups (p < 0.0001, p < 0.0001, p = 0.001, respectively). CONCLUSION: We detected unfavorable effects of I/R on erythrocyte deformability, which may impair blood fl ow and hence tissue perfusion in infrarenal rat aorta. We also found that cerium oxide had benefi cial effects by reversing undesirable effects of I/R. Further studies with larger volume are required to support our promising results (Fig. 1, Ref. 24).

Interest in cerium-based coatings has increased in recent years due to their low toxicity, biocompatibility, and improved corrosion protection performance. The formation of a coating from a solution containing cerium nitrate (Ce(NO 3) 3) has been investigated as a good surface modification strategy for the production of protective coatings on 316L SS. The effect of various additives in the treatment solution (sodium molybdate, sodium salicylate, and ascorbic acid) on the corrosion protection properties of the coatings was evaluated. The protection performance of the coated samples in a physiological simulated fluid (Ringer solution) was examined by electrochemical methods. The composition and morphology of all coatings were analyzed by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDX).

The outstanding properties of cerium oxide from its capacity to transit from Ce 3+ to Ce 4+ (and from Ce 4+ to Ce 3+) make it very useful for a wide range of technological applications of great importance. We performed experiments sending pulses of CO that interact with the surface of nano cubes of CeO 2 with low index faces (100). We model this process through the statistical description of the creation of oxygen vacancies leading to the appearance of Ce 2 O 3. The model is able to predict the composition of the equilibrium nano cubes surface under different experimental conditions. The theoretical results are compared with the obtained experimental values of CO consumption, which is related to the presence of Ce 3+ atoms.

Cerium oxide is an interesting mixed valence compound of great technological importance. We model the growth of thin films of this substance by describing the statistical nucleation of atomic units containing Ce 3+ and Ce 4+. The theoretical results are compared with available experimental values of the magnetic susceptibility of the material, which is related to the proportion of magnetic atoms in the solid. The model is able to predict the composition of the final solid under different preparation conditions, namely the oxygen content of the precursor and the temperature of the substrate.

Nanocrystalline cerium(IV) oxide (CeO 2 , ceria) particles were produced via the hydrothermal treatment of cerium nitrate hexahydrate with various alkali metal hydroxides (MOH: M = Li, Na, K). Experimental conditions such as [MOH], reaction temperature, and reaction time were studied. Particle morphology as well as size of crystallites was precisely controlled by choice of experimental conditions. While rod-shaped particles were obtained at 120 C, well-defined nanocubes were formed at higher temperatures regardless of the choice of MOH. Examination of particle growth kinetics, in the final stages of crystallization, showed that particle growth rate is controlled by two different mechanisms. Grain boundary diffusion controls the particle growth in the presence of NaOH with an activation energy of 113.8 kj/mol and surface diffusion for LiOH ad KOH with the activation energy of 43.0-150.9 kj/mol, respectively. In addition, the particles exhibit strong violet and blue emissions at 400 nm and 370 nm. The former emission originates from excitation of a wide band gap of CeO 2. The latter one is attributed to the trivalency of the cerium ion and appears to be sensitive to all the experimental conditions studied. Both extending reaction time and increasing temperature reduce the intensity of the 370 nm emission and increase the intensity of the 400 nm emission.

Synthesis of truly monodisperse nanoparticles and their structural characterization to atomic precision are important challenges in nanoscience. Success has recently been achieved for metal nanoparticles, particularly Au, with diameters up to 3 nm, the size regime referred to as nanoclusters. In contrast, families of atomically precise metal oxide nanoparticles are currently lacking, but would have a major impact since metal oxides are of widespread importance for their magnetic, catalytic and other properties. One such material is colloidal CeO 2 (ceria), whose applications include catalysis, new energy technologies, photochemistry, and medicine, among others. Here we report a family of atomically precise ceria nanoclusters with ultra-small dimensions up to~1.6 nm (~100 core atoms). X-ray crystallography confirms they have the fluorite structure of bulk CeO 2 , and identifies surface features, H + binding sites, Ce 3+ locations, and O vacancies on (100) facets. Monodisperse ceria nanoclusters now permit investigation of their properties as a function of exact size, surface morphology, and Ce 3+ :Ce 4+ composition.

− All the Ni-Co-Ce-ZrO 2 mixed oxides are prepared by co-precipitations methods. Methanation of CO and H 2 reaction is screened tested over different fractions of cerium (2, 4, 7 and 12 wt.%) over Ni-Co/ZrO 2 bimetallic catalysts are investigated. The mixed oxides are characterized by XRD, CO-Chemisorption, TGA and screened methanation of CO and H 2 at 360 °C for 3000 min on stream at typical ratio CO:H 2 =1:1. In Ni-Co/CeZrO 2 series 2 wt.% Ce loading catalyst shows most promising catalyst for CH 4 selectivity than CO 2 , which directs more stability with less coke formation. The high activity is attributed to the better bimetallic synergy and the well-developed crystalline phases of NiO, ZrO 2 and Ce-ZrO 2 . Other bimetallic mixed oxides NCoZ, NCoCZ has faster deactivation with low methanation activity. Finally, 2 wt.% Ce loading catalyst was found to be optimal coke resistant catalyst.

Background:Synthesis of metal oxides nanoparticles with specific morphology and size has become the subject of many experimental protocols. Biosynthesis of the nanoparticles using plants is more preferable than physical and chemical methods because of its environmental friendliness.Objective:The purpose of this study was to report the potential for green synthesis of cerium oxide nanoparticles using plant extracts with a high content of phenolic metabolites.Methods:We have synthesized the CeO2 nano- and microparticles using Petroselinum crispum aqueous extract. The particles were characterized by UV-visible spectroscopy, IR spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscope (TEM) and dynamic light scattering analysis. For detection the reduction capacity of the extract the evaluation of total phenolic and flavonoid content as well as high-performance liquid chromatography-mass spectrometry (HPLC-MS) were performed. Biological ...

Polymer electrolyte fuel cell membranes are degraded by oxygen free radical attack. The addition of cerium oxide and doped cerium oxide nanoparticles improves membrane stability as measured by open circuit voltage and low humidity accelerated stress testing. In this work we varied the crystallite size of ceria nanoparticles and investigated their role in enhancing durability of the PEM fuel cell. We found that the ratio of the free radical production to hydrogen peroxide decomposition rates provides a novel approach to characterize the efficiency of free radical scavenging catalysts. Nanoparticle crystallite size and doping plays a significant role in determining the surface area normalized efficiency of ceria based free radical scavengers.

Herein we demonstrate the extra-low-temperature oxygen storage capacity (OSC) of cerium oxide nanocrystals with cubic (100) facets. A considerable OSC occurs at 150°C without active species loading. This temperature is 250°C lower than that of irregularly shaped cerium oxide. This result indicates that cubic (100) facets of cerium oxide have the characteristics to be a superior low-temperature catalyst.

Acceptability and relevance of nanoparticles in the society is greatly improved using a safer-by-design strategy. However, this is difficult to implement when too late in the development process or when nanoparticles are already on the market (e.g., TiO 2 ). We employ this strategy for emerging nanoparticles of lanthanide oxysulfide of formula (Gd,Ce) 2 O 2 S, relevant for photocatalysis as well as for multimodal imaging, as the bandgap of the nanoparticles, related to their Ce content, impacts their ability to absorb visible light. As a first step, we investigated the production of reactive oxygen species (ROS) as a function of cerium content, in abiotic conditions and in vitro using murine macrophage RAW 264.7 cell line. We demonstrate that, at sub-lethal doses, Ce-containing oxysulfide nanoparticles are responsible for a higher ROS intracellular formation than cerium-free Gd 2 O 2 S nanoparticles, although no significant inflammatory response or oxidative stress was measured. Moreover, there was no significant loss of cerium as free cation from the nanoparticles, as evidenced by X-ray fluorescence mapping. Based on these results, we propose a risk analysis for lanthanide oxysulfide nanoparticles, leading to a technology assessment that fulfills the safer-by-design strategy.

Acceptability and relevance of nanoparticles in the society is greatly improved using a safer-by-design strategy. However, this is difficult to implement when too late in the development process or when nanoparticles are already on the market (e.g., TiO2). We employ this strategy for emerging nanoparticles of lanthanide oxysulfide of formula (Gd,Ce)2O2S, relevant for photocatalysis as well as for multimodal imaging, as the bandgap of the nanoparticles, related to their Ce content, impacts their ability to absorb visible light. As a first step, we investigated the production of reactive oxygen species (ROS) as a function of cerium content, in abiotic conditions and in vitro using murine macrophage RAW 264.7 cell line. We demonstrate that, at sub-lethal doses, Ce-containing oxysulfide nanoparticles are responsible for a higher ROS intracellular formation than cerium-free Gd2O2S nanoparticles, although no significant inflammatory response or oxidative stress was measured. Moreover, the...

The goal of this work was to synthesize new cerium oxide-based nano-additives to minimise emissions from spark ignition (SI) engines fueled with gasoline blends, such as carbon monoxide (CO), unburned hydrocarbons (HC) and oxides of nitrogen (NO x). To investigate the effect of transition metal dopants on their respective catalytic oxidation activity, nano-sized CeO 2 catalysts co-doped with Mn, Fe, Cu and Ag ions were successfully produced by a simple hydrothermal technique. The synthesis of nano-catalysts with cubic fluorite geometry was confirmed by XRD data. The addition of transition metal ions to the CeO 2 lattice increased the concentration of structural defects like oxygen vacancies and Ce 3+ ions, which are advantageous for the catalytic oxidation reaction, as also supported by XAFS and RAMAN analysis. Further, nano-gasoline fuel emission parameters are measured and compared to straight gasoline fuel. The results demonstrated that harmful exhaust pollutants such as CO, HC and NO x were significantly reduced. The high surface area, better redox characteristics and presence of additional oxygen vacancy sites or Ce 3+ ions have been linked to the improved catalytic performance of the synthesized catalyst.

The atomic and electronic structure of ceria surfaces exhibiting step edges have been studied by means of periodic density functional (LDA+U and GGA+U) calculations. A variety of stoichiometric and nonstoichiometric models of increasing complexity have been designed. The electronic structure has been explored using the topological Bader analysis, the calculated magnetic moments and the ELF (electron localization function) maps. It is concluded that Ce 3+ atoms may exist even in stoichiometric extended ceria samples and that the presence of oxygen vacancies in stepped surfaces also induces the presence of Ce 3+ atoms although in both cases, the reduced atoms tend to occupy the sites with smallest possible coordination number.

Objective: Cyclophosphamide (CP), as an anticancer agent has side effects, especially hepatotoxicity. Cerium oxide nanoparticles [nanoceria (NC)], which act as antioxidants, have a protective effect against oxidative stress-induced toxicity. This study evaluated the preventive effect of NC in hepatotoxicity induced by CP. Materials and Methods: Thirty-two mice were randomly distributed into four groups: control (received only normal saline), NC (received NC 100 μg/kg for 3 days, intraperitoneally), CP (received CP 200 mg/kg single dose on the third day of the study, intraperitoneally), and NC+CP (NC 100 μg/kg and CP 200 mg/kg). Two days after the final treatment, oxidative stress marker (MDA and GSH) and alanine aminotransferase (ALT), aspartate aminotransferase (AST), and alkaline phosphatase (ALP) levels were measured, and histopathological and immunohistochemical examinations were performed for determining the effects of NC on hepatotoxicity. Results: CP-induced hepatotoxicity was evident by the significant elevation of liver enzyme levels and alteration in oxidative stress marker levels. Additionally, histopathological changes and apoptosis were markedly increased. NC decreased MDA level, increased GSH level and decreased liver enzyme levels in CP-treated mice. In addition, NC pretreatment could be alleviated by the immunoreactivity of caspase-3 in CP-treated mice compared with the CP group. Conclusion: NC showed a potent antioxidant effect in hepatotoxicity induced by CP. The study suggested that NC through its antioxidant and anti-apoptotic properties has a protective effect against hepatotoxicity induced by CP.