Cerium Acetate Research Articles

Electroless nanoceria films on nickel-based superalloy

ABSTRACT Ceria films were deposited by electroless method on a nickel-based superalloy, Superni 75, to improve its performance at high temperatures. Ceria was produced from cerium acetate using triethanolamine as the reducing agent. The films were produced at three concentrations – 0.1, 0.2 and 0.3 M of cerium acetate, to study the effect of increasing cerium concentration. For comparative study, the coated and bare substrates were oxidized at 1173 K for 100 h in air. The morphology and the chemistry of the oxide scale formed were analysed using FEG-SEM/EDS and XRD. It has been observed that increasing the cerium concentration in the film increases the oxidation resistance of the substrate which is evident from the calculated parabolic rate constant. It was also observed that the morphology of the scale improves with the increase in the concentration of cerium in the film. The scale formed on the ceria-coated substrate at 0.3 M concentration is dense and more uniform.

Two-dimensional Acetate-based Light Lanthanide Fluoride Nanomaterials (F-Ln, Ln = La, Ce, Pr, and Nd): Morphology, Structure, Growth Mechanism, and Stability.

Discovery of novel two-dimensional (2D) materials is of fundamental importance but remains challenging. In this work, we design a simple and facile bottom-up approach to fabricate a new family of 2D acetate-based light lanthanide fluoride nanomaterials (F-Ln, Ln = La, Ce, Pr, Nd) at room temperature and atmosphere pressure, for the first time. Various characterization techniques confirm that as-synthesized F-Ln exhibit an ultrathin morphology with thickness up to 1.45 nm and lateral dimensions up to several hundred nanometers. Microstructure analysis demonstrates that F-Ln are a series of defect-rich 2D nanomaterials, which consist of nanocrystals with sub-10 nm domains. Structure characterization of F-Ce, a typical example, infers that BN-like F-Ce one-atom-layers sandwiched by intercalated acetate anions stack alternately along [001] direction to form nanocrystal building blocks of F-Ce. The study of growth mechanism suggests that three procedures are involved in the formation of F-Ce: hydrolysis reaction of cerium(III) acetate, structure transformation induced by fluorine ions, and assembly process guided by acetate anions. The as-prepared nanosheets show excellent stability with respect to environment stimuli such as air, heat, solvent, and high-energy electron beam. This study enriches the library of 2D materials and paves the way for future application of such 2D materials in areas such as catalysis, adsorption, separation, and energy storage/conversion.

Study of the synergistic effect of cerium acetate and sodium sulphate on the corrosion inhibition of AA2024-T3

This study presents a detailed characterisation of the AA2024-T3 immersed in NaCl + Ce(OAc)3 solutions without and with added Na2SO4 at various concentrations aimed to understand the synergistic effect of cerium and sulphate ions on corrosion inhibition.The corrosion process was evaluated using micro- and macro-scale electrochemical techniques performing anodic polarisation and electrochemical impedance spectroscopy measurements. The cerium species on alloy surface were analysed using a scanning electron microscope coupled with energy dispersive X-ray spectroscopy as well as atomic force and scanning Kelvin probe force microscopy.The results show a corrosion inhibition of AA2024-T3 immersed in NaCl + Ce(OAc)3, which becomes more effective in the presence of Na2SO4 due to a synergistic effect between ions involved in the inhibition process. The local techniques confirm the formation of insoluble cerium species on intermetallics and on aluminium matrix. The synergistic effect results in the formation of more compact and more durable film, which significantly retards the corrosion process.

Preparation of Ce doped ZnO microspheres and its visible-light photocatalytic activity

Using zinc acetate, cerium acetate and glycerol as main raw materials, the Ce doped ZnO (Ce/ZnO) with molar doping ratio of 0.1%, 0.5%, 1.0%, 2.0% and 3.0% were prepared by hydrothermal method at 200 °C. The structure and morphology of prepared Ce/ZnO were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), electron spectroscopy (EDS) and diffuse reflectance spectroscopy (DRS). The visible-light photocatalytic activity of prepared Ce/ZnO was investigated by methyl orange which was used as simulated sewage. The results show that the optimum doping amount of Ce/ZnO is 0.5% Ce, and the band gap width of 0.5% Ce/ZnO is red-shifted from 3.12 eV to 2.79 eV. The morphology of ZnO and Ce/ZnO are all mainly spherical particles. The average particle diameter of ZnO and Ce/ZnO are all from about 3μm to 4μm. The 0.5% Ce/ZnO show highly photocatalytic activity for the degradation of methyl orange under visible light irradiation, and the degradation of methyl orange conforms to the first order power with the apparent rate in paper 0.018 min−1.

Construction of trace silver modified core@shell structured Pt-Ni nanoframe@CeO2 for semihydrogenation of phenylacetylene

The Pt-Ni nanoframe catalysts have attracted great interest owing to their unique electronic structure and excellent catalytic performance. However, the stability of the tenuous edges of nanoframe-structures is dissatisfactory and their universal applications in catalytic market beyond electrocatalytic reactions are yet to be tapped and explored. Herein, we developed a new core@shell structured Pt-Ni nanoframe@CeO2 (Pt-Ni NF@CeO2) composite via etching the Ni from inhomogeneous Pt-Ni rhombic dodecahedra (Pt-Ni RD) by cerium(III) acetate hydrate (Ce(OAc)3). In this path, Pt-Ni RD was used as self-sacrificial template, while the Ce(OAc)3 serves as the provider of the Ce3+ source and OH− for the formation of CeO2 shell, etchant of Pt-Ni RD, and the surface modification agent. By this way, the etching of Pt-Ni RD and the formation of the CeO2 shell are simultaneously proceeded to form the final Pt-Ni NF@CeO2 in one step. The obtained Pt-Ni NF@CeO2 exhibits strong interfacial charge transfer interaction between Pt-Ni NF core and CeO2 shell even without reduction treatment, leading to enhanced catalytic activity in the hydrogenation of phenylacetylene. After introduction of trace silver, the Pt-Ni-Ag4.9 NF@CeO2 achieves remarkable catalytic performance for the selective conversion of phenylacetylene to styrene: high conversion (100%), styrene selectivity (86.5%), and good stability. It reveals that encapsulation noble metal nanoframes into metal oxide to form core@shell structured hybrids will indeed enhance their stability and catalytic properties. Particularly, this work expends the application of noble metal nanoframes materials to hydrogenation reactions.

Half-Encapsulated Au Nanorods@CeO2 Core@Shell Nanostructures for Near-Infrared Plasmon-Enhanced Catalysis

The technology of surface plasmon resonance (SPR) is considered to be highly attractive approach to directly harvest optical energy for photocatalytic reactions. However, photocatalytic application is limited mainly by inefficient absorption of catalysts in the visible and infrared range. In this work, an anisotropic Au@CeO2 mushroom-like core@shell nanostructure is designed by controlled hydrolysis of the cerium acetate utilizing the cetyltrimethylammonium bromide (CTAB) as a soft template. Special aspect ratio of the Au nanorods (Au NRs) and the anisotropy of the nanostructures increase the plasmon absorption in the frequency near-infrared range (NIR). Upon 808 nm laser illumination for 7 min, the temperature of the solution containing 75 ppm half-encapsulated Au NRs@CeO2 (h-Au@CeO2) increases up to 53.8 °C. Besides exhibiting plasmon-enhanced photothermal properties, h-Au@CeO2 also has good 4-nitrophenol (4-NP) catalytic reduction activity under near-infrared laser. The anisotropy of h-Au@CeO2 promotes...

Emission and vibration analysis of diesel engine fuelled diesel fuel containing metallic based nanoparticles

This experimental study reports the results of emission and vibration characteristics of compression ignition (CI) engine with variable compression ratios (VCR) using nanoparticles added to diesel fuels. Three different nanoparticles namely, titanium (IV) dioxide (TiO2), copper (II) nitrate (Cu(NO3)2) and cerium (III) acetate hydrate (Ce(CH3CO2)3·H2O) were used with conventional diesel fuel at the dosage of 25 ppm and 50 ppm in order to prepare the four different test fuels. The engine tests were implemented in a single cylinder diesel engine under 4 Nm and 8 Nm engine load at a constant engine speed of 1500 rpm and at compression ratios (CR) of 17:1 and 18:1. The results showed that nanoparticles addition in the diesel fuels in ppm level did not caused any complications in the physicochemical properties but a slightly increase in heating value and cetane number. In addition, the combined effect of titanium dioxides and cerium acetate hydrate nanoparticles significantly reduced pollutants emissions regardless of NOx emissions. Especially, addition of cerium acetate hydrate into the blend fuels has become a dominant factor in the reduction of the harmful exhaust emissions. Furthermore, it was revealed that sound pressure level of engine block decreased with the addition of nanoparticles into diesel fuel which is parallel to vibration results.

Oxalic acid assisted synthesis of the gadolinium-doped ceria oxide-ion conductor as electrolyte for the solid oxide fuel cells

The aim of this paper is to investigate the thermal behavior of as-prepared Gd–Ce–O acetate–oxalate (GCO–AO) precursors and their affinity to the decomposition processes of the starting materials by means of thermogravimetric and differential scanning calorimetric analyses (TG/DTG/DTA). Moreover, the influence of the temperature, heating atmosphere, and heat treatment time on both the morphology and crystal structure of the Ce–Gd–O gel precursor were additionally investigated in detail using a scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT–IR). The obtained TG/DTG/DTA results revealed that the formation of the gadolinium-doped ceria (GDC) ceramic was closely related to the thermal decomposition processes of the initial compounds: gadolinium (III) acetate and cerium (IV) acetate. The powder XRD patterns of the heat-treated GCO–AO sample revealed that the crystallization process for the GDC ceramic starts at 1173 K, whereas the temperature and heat treatment time significantly affected on the surface morphology and the size of the obtained particles. Besides, the spectra of FT–IR analysis showed that the vibration modes of the oxygen–metal–oxygen (O–M–O) in GDC ceramic heat-treated at different temperatures were equivalent, although the sample heat-treated at 1273 K demonstrated a completely different optical behavior. In that case a strong absorption outspread in the region from 1000 to 500 cm−1 was observed, which could be attributed to the initial formation of the nano-sized spherical particles in size of about 50–100 nm.

The influence of additional salts on corrosion inhibition by cerium(III) acetate in the protection of AA7075-T6 in chloride solution

The synergistic or adverse effects of the addition of NaOAc, NaNO3 and Na2SO4 on the performance of cerium(III) acetate as inhibitor of corrosion of aluminium alloy 7075-T6 in 0.1 M NaCl were investigated. The corrosion properties were evaluated using electrochemical polarisation and impedance methods. The composition and morphology of scribed samples during a 1-month immersion test were characterised using morphological and chemical analyses. The influence of additional salts on cerium precipitation was confirmed by acid-base titration. The most efficient long-lasting corrosion inhibition was achieved by synergism between Ce(OAc)3 and Na2SO4 and ascribed to low solubility of the product formed.

Controllable hydrothermal synthesis of bundled ZnO nanowires using cerium acetate hydrate precursors

ZnO nanowire arrays were grown by the hydrothermal decomposition of zinc acetate dehydrate in precursor solutions containing cerium acetate hydrate. The effects of the Ce precursor on the hydrothermal synthesis of ZnO nanowires were investigated as a function of the Ce concentration. It was found that all the samples exhibited preferential orientation toward the c-plane and the Ce precursor had no effect on the lattice constant in the ZnO nanowires. ZnO nanowires grown in solutions containing 1 and 2 at% Ce precursors were bent and bundled, suggesting that solutions containing adequate amounts of Ce precursors enable the top surfaces of the vertically aligned ZnO nanowires to be either positively or negatively charged, and that electrostatic interactions among these local charges causes bending and bundling of the ZnO nanowires. Thus, Ce precursors in the solutions can control the morphology of the ZnO nanowires, causing them to be bent and bundled. We suggest that the bundled ZnO is applicable to Dye-sensitized solar cells because it can be enhanced adsorbed dye amounts in devices.

Role of Cerium Compounds in Fusarium Wilt Suppression and Growth Enhancement in Tomato ( Solanum lycopersicum).

The use of nanoparticles in plant protection may reduce pesticide usage and contamination and increase food security. In this study, three-week-old Solanum lycopersicum seedlings were exposed, by root or foliar pathways, to CeO2 nanoparticles and cerium acetate at 50 and 250 mg/L prior to transplant into sterilized soil. One week later, the soil was inoculated with the fungal pathogen Fusarium oxysporum f. sp. lycopersici (1 g/kg), and the plants were cultivated to maturity in a greenhouse. Disease severity, biomass/yield, and biochemical and physiological parameters were analyzed in harvested plants. Disease severity was significantly reduced by 250 mg/L of nano-CeO2 and CeAc applied to the soil (53% and 35%, respectively) or foliage (57% and 41%, respectively), compared with non-treated infested controls. Overall, the findings show that nano-CeO2 has potential to suppress Fusarium wilt and improve the chlorophyll content in tomato plants.

Nano ceria as xylene sensor – Role of cerium precursor

Cerium oxide (CeO2) thin films were deposited on glass substrates by spray pyrolysis technique using three different precursors namely cerium chloride heptahydrate, cerium nitrate hexahydrate and cerium acetate hydrate. Structural, morphological, optical, electrical and sensing properties of the CeO2 thin films were examined. X-ray diffraction patterns of spray deposited CeO2 thin films confirmed the formation of polycrystalline cubic fluorite crystal structure. The surface morphologies of CeO2 films were observed using field emission scanning electron microscope. The optical band gap observed from luminescence spectra varied from 3.23 to 3.57 eV. Room temperature sensing characteristics of CeO2 thin films towards acetone, ethanol, xylene and toluene were observed. CeO2 thin film deposited using cerium acetate hydrate at 0.1 M concentration exhibited a better response towards xylene with fast response and recovery times of 224 and 13 s respectively at ambient temperature.

Optical performances of mono‐dispersed spherical YAG:Ce3+ nano‐phosphor achieved by one‐pot synthesis

AbstractMono‐dispersed spherical YAG:Ce3+ nano‐phosphors were successfully synthesized by a one‐pot glycol‐thermal process using aluminum isopropoxide, yttrium, and cerium acetate hydrates as the precursor, (1,4)‐butanediol as the solvent, ethidenediamine as the additive agent that can both control the morphology and improve the optical performances of the as‐achieved products. The as‐prepared YAG:Ce3+ nano‐phosphors displayed mono‐dispersed spheres of about 150 nm and an improved optical performance with a quantum yield (QY) of 41% and good photostability, indicating that they have a considerable potential to be applied in solid‐state lighting or used as coatings in other optical electronic devices.

Synthesis and Characterization of Alumina-Ceria Core-Shell Nanoparticles Using a Wet Chemical Method

In this study, α-Al2O3-CeO2 core-shell nanoparticles were synthesized from the cerium acetate and the commercial α-Al2O3 nanoparticles as the starting materials via a wet chemical method. Poly (acrylic acid) (PAA) as an additive compound was used for the surface modification of alumina nanoparticles. Also, the effects of PAA content, pH value and calcination temperature on the synthesis behavior of α-Al2O3-CeO2 nanoparticles were investigated. The formation of core-shell structure was investigated using X-ray diffraction (XRD) and field-emission scanning electron microscopy (FE-SEM) equipped with energy dispersive X-ray spectroscopy (EDS). The results indicated that at the PAA=1.5 wt. %, pH=6 and calcination temperature=1150°C (as optimal conditions), the core-shell nanoparticles with alumina core and ceria shell and homogeneous size distribution were synthesized successfully.

Synthesis of Mesoporous Cerium Oxide (CeO2) Nanoparticles and Effect of Cerium Precursors on Transamidation of Acetamide with N-Octylamine Under Solvent-Free Conditions

Mesoporous cerium oxide (CeO2) nanoparticles act as an effective heterogeneous catalyst for the transamidation reaction of amides with amines. The mesoporous CeO2 nanoparticles were prepared by hydrothermal method using different cerium precursor such as: cerium(III) chloride heptahydrate [CeCl3 · 7H2O], cerium nitrate hexahydrate [Ce(NO3)3 · 6H2O], ceric ammonium nitrate [(NH4)2Ce(NO3)6], and cerium(III) acetate [Ce(C2H3O2)3 · 1.5H2O]. It shows highest catalytic activity for transamidation of acetamide with N-octylamine under solvent free conditions. This is the first example of a heterogeneous catalyst for transamidation using aliphatic amines as substrates. The X-ray diffraction, BET surface area analysis, and FT-IR characterizations of CeO2 suggested its excellent catalytic activity for transamidation reaction.

Highly effective self-propagating synthesis of CeO2-doped MnO2 catalysts for toluene catalytic combustion

Using a facile new synthesis method, the fabrication of cerium oxide doped birnessite MnO2 (δ-MnO2) catalysts has been operated, for the toluene catalytic combustion. These samples were investigated by XRD, Raman, TEM, BET, H2-TPR and XPS techniques and their catalytic activities were investigated and compared. The catalytic combustion of toluene was investigated as the model reaction for VOCs abatement. The several CeO2/MnO2 based nano composites were accomplished via controlling the molar proportion of potassium permanganate and cerium acetate raw materials. The subtle CeO2 doped δ-MnO2 catalyst displayed better reducibility at lower reduction temperature, with the higher Mn4+/Mn3+ ratio, which converts completely the 1000ppm toluene to CO2 and H2O at 318°C and its T90 is 277°C. The excellent catalytic performance of Mn12Ce1Ox catalyst might be resulted from the synergistic effect between the highly dispersed CeO2 nanoparticles and the δ-MnO2 substrate at their interface. These new observations provide a new perspective on the design of the high activity catalyst for decomposing the volatile organic compounds (VOCs abatement).

Combustion synthesis of CeO2 nanoparticles for aging and inhalation exposure studies

The continuous production of an aerosol of CeO2 nanoparticles is valuable for nanoparticle aging and inhalation exposure studies, compared with other synthesis processes that require subsequent handling and preparation of the aerosol which can alter nanoparticle properties. This paper describes a new method for producing CeO2 nanoparticles and a novel facility where a combustion synthesis system was integrated in-line with an atmospheric ultraviolet (UV) aging chamber and an inhalation exposure system. Poly-disperse CeO2 nanoparticles were continuously produced to demonstrate the capability of the integrated nanoparticle synthesis and delivery system. The CeO2 nanoparticles were products of combustion of cerium acetate hydrate, a solid-phase precursor, with gas-phase hydrogen, oxygen, and nitrogen reactants. Results for particle size, concentration, crystal structure, and morphology are presented for the CeO2 nanoparticles produced in this study with and without UV exposure in the aging chamber. The setup successfully demonstrated the capability to maintain a steady CeO2 particle number concentration throughout four hours of operation with ~90% of the particles less than 200nm in size, corresponding to a mass concentration of approximately 500μg/m3. The CeO2 nanoparticle morphology (including primary particle size and aggregate size) and crystalline phase showed minimal sensitivity to UV aging in the ambient urban environment used in the study. The results indicate other species co-produced in diesel fuel systems (where CeO2 nanoparticles are used as a fuel additive) or found in the urban atmosphere may be required to affect the aging of CeO2 nanoparticles observed in previous studies.

Nutritional quality assessment of tomato fruits after exposure to uncoated and citric acid coated cerium oxide nanoparticles, bulk cerium oxide, cerium acetate and citric acid

Little is known about the effects of surface modification on the interaction of nanoparticles (NPs) with plants. Tomato (Solanum lycopersicum L.) plants were cultivated in potting soil amended with bare and citric acid coated nanoceria (nCeO2, nCeO2+CA), cerium acetate (CeAc), bulk cerium oxide (bCeO2) and citric acid (CA) at 0–500 mg kg−1. Fruits were collected year-round until the harvesting time (210 days). Results showed that nCeO2+CA at 62.5, 250 and 500 mg kg−1 reduced dry weight by 54, 57, and 64% and total sugar by 84, 78, and 81%. At 62.5, 125, and 500 mg kg−1 nCeO2+CA decreased reducing sugar by 63, 75, and 52%, respectively and at 125 mg kg−1 reduced starch by 78%, compared to control. The bCeO2 at 250 and 500 mg kg−1, increased reducing sugar by 67 and 58%. In addition, when compared to controls, nCeO2 at 500 mg kg−1 reduced B (28%), Fe (78%), Mn (33%), and Ca (59%). At 125 mg kg−1 decreased Al by 24%; while nCeO2+CA at 125 and 500 mg kg−1 increased B by 33%. On the other hand, bCeO2 at 62.5 mg kg−1 increased Ca (267%), but at 250 mg kg−1 reduced Cu (52%), Mn (33%), and Mg (58%). Fruit macromolecules were mainly affected by nCeO2+CA, while nutritional elements by nCeO2; however, all Ce treatments altered, in some way, the nutritional quality of tomato fruit. To our knowledge, this is the first study comparing effects of uncoated and coated nanoceria on tomato fruit quality.

Controllable synthesis, characterization, and CO oxidation activity of CeO2 nanostructures with various morphologies

CeO2 nanostructures with various morphologies were prepared through controlling preparation conditions via a hydrothermal method without any surfactants and templates. Cerium acetate, cerium chloride and cerium nitrate were used as cerium precursors to investigate the influence of anions on the growth process of CeO2 nanostructures. The morphology evolution of CeO2 and Ce(OH)3 nanostructures indicates that the anions play an important role for the growth kinetics of resulting samples. Cl− and Ac− ions promoted the formation of one dementional (1D) CeO2 nanostructures such as nanowires, nanorods and nano hexagonal prisms, while the oxidizing anion NO3- facilitated the synthesis of CeO2 nanocubes. The hydrothermal reaction temperature is another key to govern the morphologies of CeO2 nanostructures. The formation process of the nanostructures was explored and the possible growth mechanism was discussed. The variety of CeO2 nanostructures represented inequable catalytic performance for CO oxidation. Because of different surface areas and structures, CeO2 nanowires revealed the best catalysis performance while that of the nanocubes is the worst.

Effects of uncoated and citric acid coated cerium oxide nanoparticles, bulk cerium oxide, cerium acetate, and citric acid on tomato plants

Little is known about the physiological and biochemical responses of plants exposed to surface modified nanomaterials. In this study, tomato (Solanum lycopersicum L.) plants were cultivated for 210days in potting soil amended with uncoated and citric acid coated cerium oxide nanoparticles (nCeO2, CA+nCeO2) bulk cerium oxide (bCeO2), and cerium acetate (CeAc). Millipore water (MPW), and citric acid (CA) were used as controls. Physiological and biochemical parameters were measured. At 500mg/kg, both the uncoated and CA+nCeO2 increased shoot length by ~9 and ~13%, respectively, while bCeO2 and CeAc decreased shoot length by ~48 and ~26%, respectively, compared with MPW (p≤0.05). Total chlorophyll, chlo-a, and chlo-b were significantly increased by CA+nCeO2 at 250mg/kg, but reduced by bCeO2 at 62.5mg/kg, compared with MPW. At 250 and 500mg/kg, nCeO2 increased Ce in roots by 10 and 7 times, compared to CA+nCeO2, but none of the treatments affected the Ce concentration in above ground tissues. Neither nCeO2 nor CA+nCeO2 affected the homeostasis of nutrient elements in roots, stems, and leaves or catalase and ascorbate peroxidase in leaves. CeAc at 62.5 and 125mg/kg increased B (81%) and Fe (174%) in roots, while at 250 and 500mg/kg, increased Ca in stems (84% and 86%, respectively). On the other hand, bCeO2 at 62.5 increased Zn (152%) but reduced P (80%) in stems. Only nCeO2 at 62.5mg/kg produced higher total number of tomatoes, compared with control and the rest of the treatments. The surface coating reduced Ce uptake by roots but did not affect its translocation to the aboveground organs. In addition, there was no clear effect of surface coating on fruit production. To our knowledge, this is the first study comparing the effects of coated and uncoated nCeO2 on tomato plants.