CeO2 Material Research Articles

Electrode material fabricated by loading cerium oxide nanoparticles on reduced graphene oxide and its application in electrochemical sensor for tryptophan

Facile fabrication of advanced electrode material is highly desired for novel electrochemical sensor development. Herein, cerium oxide (CeO2) nanoparticles were successfully loaded on reduced graphene oxide (RGO) by one-step hydrothermal synthesis approach, and the as-prepared nanocomposite (CeO2/RGO) was used as novel electrode material for electrochemical detection of tryptophan. The structure and composition of CeO2/RGO nanocomposite were fully characterized by transmission electron microscope (TEM), X-ray powder diffractometry (XRD) and X-ray photoelectron spectroscopy (XPS), respectively. The electrochemical properties were characterized by several techniques such as cyclic voltammetry (CV), differential pulse voltammetry (DPV), and electrochemical impedance spectroscopy (EIS). It was found that the CeO2/RGO nanocomposite electrode exhibits an enhanced peak current response compared with individual CeO2 or RGO material. The electrochemical sensor based CeO2/RGO material showed a selective and sensitive response toward tryptophan determination, and a linear range of 0.2–25 μM with a detection limit of 80 nM (S/N = 3) was achieved. The present electrochemical sensor displayed an excellent stability and reproducibility, and was successfully applied in the determination of tryptophan in real food and biological samples.

G-C3N4/CeO2 Binary Composite Prepared and Its Application in Automobile Exhaust Degradation.

Vehicle exhaust seriously pollutes urban air and harms human health. Photocatalytic technology can effectively degrade automobile exhaust. This work prepared g-C3N4/CeO2 photocatalytic material by constructing heterojunctions. Four kinds of g-C3N4/CeO2 composite photocatalytic materials with different mass ratios were prepared. An indoor exhaust gas purification test was carried out under natural light and ultraviolet light irradiations. The optimum mass ratio of g-C3N4 material and CeO2 material was determined by evaluating the exhaust gas degradation effective. Moreover, the structure and morphology of the g-C3N4/CeO2 composite were investigated with microscopic characterization experiments (including XRD, TG-DSC, FT-IR, UV-Vis, SEM and XPS). The results obtained were that the optimum mass ratio of g-C3N4 material to CeO2 material was 0.75. The degradation efficiencies under ultraviolet irradiation in 60 min for HC, CO, CO2, NOX were 7.59%, 12.10%, 8.25% and 36.82%, respectively. Under visible light conditions, the degradation efficiency in 60 min for HC, CO, CO2 and NOX were 15.88%, 16.22%, 10.45% and 40.58%, respectively. This work is useful for purifying automobile exhaust in the future.

Photoelectrocatalytic evaluation of EG-CeO2 photoanode on degradation of 2,4-dichlorophenol

Herein, we report the photoelectrocatalytic degradation of 2,4-dichlorophenol as a model chlorinated phenolic compound on exfoliated graphite-cerium(IV) oxide (EG-CeO2) photoelectrode. The EG-CeO2 nanocomposites with and without trimethoxymethylsilane (TMOMS) were synthesized using impregnation ultrasonic agitation and comprehensively characterized by XRD, FTIR, Raman, TGA, DSC, FESEM, TEM, EDS, UV–Vis DRS, BET, XPS, and AFM. The SEM results revealed that the CeO2 material was entrapped within the cavities and on the surface of EG sheets. Electrochemical studies were performed using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and linear sweep voltammetry (LSV). Photoelectrocatalytic degradation of 2,4-dichlorophenol dissolved in 0.1 M Na2SO4 electrolyte was performed with chronoamperometric technique. The EG-CeO2 (TMOMS) displayed higher removal efficiency under simulated light compared to EG and EG-CeO2, respectively. The degradation efficiency of 98.7% was attained with EG-CeO2 (TMOMS) under optimum conditions of pH 6.2 and current density of 8 mA cm−2. Total organic carbon removal of about 92.6% was recorded during the degradation of 2,4-DCP under optimum conditions for 180 min. Based on the results obtained, the low-cost EG-CeO2 (TMOMS) photoelectrode has lent itself into possibility of photoelectrocatalytic degradation of organic water pollutants and can be extended to environmental samples application.

Methanol gas detection of electrospun CeO2 nanofibers by regulating Ce3+/ Ce4+ mole ratio via Pd doping

The ability of cerium oxide (CeO2) to store oxygen by its own unique redox reaction between Ce3+ and Ce4+ ions will play a crucial role in gas detection. Thus, it is proposed to regulate the ratio of Ce3+ and Ce4+ ions via palladium element (Pd) doping for the purpose of enhancing methanol response. The pristine and Pd-doped CeO2 nanofibers were successfully prepared via a low-cost electrospinning method. The TEM results confirm the successful doping of Pd into CeO2 material with uniform morphologies. The XPS results reveal that the doped palladium exists as palladium oxide (PdO), and palladium doping can affect the mole ratio of Ce3+/Ce4+ and thus the gas-sensing performance of CeO2 nanofibers. The sensing results indicate that the 3% Pd-CeO2 sensor exhibits the highest response of 6.95 to 100 ppm methanol at 200 °C, nearly 4 times larger than that of the pure CeO2 sensor. Notably, the 3% Pd-CeO2 sensor can detect low concentration down to 5 ppm CH3OH with an apparent response of 1.92. The enhanced methanol sensing performance could be assigned to the synergetic effect between the Pd doping induced Ce3+/Ce4+ ratio and PdO/CeO2 p-n heterojunctions. These results suggest the proper Pd-doped CeO2 is a potential gas-sensing material for monitoring methanol gas.

Ordered mesoporous Pt/Fe3O4–CeO2 heterostructure gel particles with enhanced catalytic performance for the reduction of 4‐nitrophenol

The unique physicochemical properties of ordered mesoporous transition metal oxides have attracted more and more attention. The hydrolysis process of metal oxide precursors is difficult to control, and it is difficult to synthesize an ordered mesoporous transition metal oxide material using the conventional template method. Ordered mesoporous Pt/Fe3O4–CeO2 heterostructure gel materials with excellent catalytic properties were successfully prepared using aerogel technology and the chemical deposition method. The Pt/Fe3O4–CeO2 material was an n–n combined heterostructured semiconductor material which consisted of a magnetic Fe3O4 layer, a CeO2 core and Pt noble metal doped nanoparticles. A layer of Fe3O4 thin film was formed on the surface of ordered mesoporous Pt/CeO2 gel matrix material using the chemical deposition method. The intriguing heterostructural features could facilitate reactant diffusion and exposure of active sites which could enhance synergistic catalytic effects between the Pt nanoparticles and CeO2 nanoparticles. Compared with Pt/CeO2, the prepared Pt/Fe3O4–CeO2 showed enhanced catalytic activity in the reduction of 4‐nitrophenol at room temperature. The catalytic activity of the heterostructure catalysts was systematically investigated using 4‐nitrophenol reduction as a model reaction. The results showed that the Pt (0.1%)/Fe3O4–CeO2 sample exhibited the optimal catalytic performance toward catalytic reduction of 4‐nitrophenol to 4‐aminophenol. The study provided a method for the preparation of heterostructure nanocatalysts with high efficiency, which would be effective for application in various catalytic reactions.

Thermocatalytic splitting of CO2 using sol-gel synthesized Co-ferrite redox materials

In this investigation, the redox reactivity of CoxFe3−xO4 materials was examined in multiple thermochemical CO2 splitting cycles. Sol-gel method was applied for the synthesis of CoxFe3−xO4 materials and the prepared gels of CoxFe3−xO4 materials were aged, dried, and further annealed up to 600 °C in air. The characterization results indicate formation of phase pure CoxFe3−xO4 materials. The thermal reduction (at 1400 °C for 60 min in the presence of inert Ar) and CO2 splitting (at 1000 °C for 30 min in the presence of CO2/Ar mixture) aptitude of each CoxFe3−xO4 material was estimated by using a high temperature set-up consisting of a thermogravimetric analyzer. From the TGA analysis, it was understood that the amounts of O2 released and CO produced by CoFe2O4 was higher and stable as compared to the other Co-ferrite materials. CoFe2O4 was capable of producing 76.2 µmol of O2/g·cycle and 139 µmol of CO/g·cycle in ten thermochemical. The thermal reduction and CO2 splitting aptitude of the CoFe2O4 was spotted to be greater than the CeO2 material.

Solar thermocatalytic conversion of CO2 using PrxSr(1−x)MnO3−δ perovskites

The prime aim of this study was to examine the thermal reduction (TR) and CO2 splitting (CS) capacity of each PrxSr(1−x)MnO3−δ (PSM) perovskite. A solution combustion synthesis (SCS) approach was applied for the synthesis of PSM perovskites wherein glycine was utilized as the fuel. As-synthesized PSM perovskites were first annealed up to 1000 °C in air and the calcined powder obtained was further analyzed using multiple characterization techniques. A high-temperature experimental set-up consisting of a Setaram SETSYS Evolution thermogravimetric analyzer (TGA) was developed and utilized for the examination of the SCS derived PSM perovskites towards thermochemical CO2 splitting reactions. The obtained results indicate that the lower Pr and higher Sr atomic concentrations are beneficial to achieve the maximum amounts of O2 released (nO2) and CO produced (nCO) in each thermochemical cycle. Based on the average nO2 and nCO, the Pr0.18Sr0.80Mn0.99O2.951 (PSM2) and Pr0.39Sr0.63Mn0.98O2.979 (PSM4) were identified as the best choices for the solar thermochemical conversion of CO2. When compared with the CeO2 material (which is considered as a yardstick), the average nO2 and nCO by all the PSM perovskites was considerably higher for each cycle.

Improving the sinterability of CeO2 by using plane-selective nanocubes

CeO2 nanocubes with (100) surface orientation are successfully synthesized and found to facilitate the sinterability of CeO2 material. The CeO2 nanocubes show a much-improved sinterability relative to CeO2 nanoparticles prepared by the conventional citric-nitrate method. The nanocubes can be successfully sintered at a relatively low temperature of 1200 °C without using any sintering aids. In contrast, a pellet using conventional CeO2 nano-powder obtained from the conventional citric-nitrate method can be densified only after sintering at 1400 °C, which is 200 °C higher than that for the CeO2 nanocube sintering, although the starting particle size of both CeO2 samples is similar. Density functional theory indicates that the surface energy of the (100) plane is significantly higher than that of the (111) plane, which is the more typical surface presentation of conventional CeO2 particles. This high surface energy allows fast growth of the CeO2 nanocubes during sintering, contributing to their improved sinterability.

Sol-gel synthesized NixFe3−xO4 for thermochemical conversion of CO2

To identify the best suitable metal oxide (MO) to split H2O/CO2, it is critical to investigate the formation of O2 vacancies during thermal reduction (TR) step and the re-oxidation of the MOs via H2O or CO2 splitting (CS) reaction. Accordingly, in the present work, we have experimentally evaluated the redox reactivity of sol-gel synthesized Ni-ferrite (NiF) in multiple temperature-swing redox cycles. The calcined powders of NiF materials were characterized for the determination of phase purity, crystallite size, and particle morphology. In case of the TGA cycles, the TR was accomplished at 1400 °C (for 60 min) and the reduced NiF was again re-oxidized via CS reaction at 1000 °C (for 30 min). The obtained outcomes indicated that, among all the NiF materials investigated i.e. Ni0.2Fe2.8O4 (NiF2), Ni0.4Fe2.6O4 (NiF4), Ni0.5Fe2.5O4 (NiF5), Ni0.6Fe2.4O4 (NiF6), Ni0.8Fe2.2O4 (NiF8), NiFe2O4 (NiF10), the NF10 has the aptitude to produce maximum quantities of O2 (nO2) and CO (nCO). When compared with the benchmark CeO2 material, the average nO2 and nCO by the NiF10 (from cycle 2 to cycle 9) was greater by 15.9 μmol/g·cycle and 30.9 μmol/g·cycle, respectively.

Copper- and Cobalt-Codoped CeO2 Nanospheres with Abundant Oxygen Vacancies as Highly Efficient Electrocatalysts for Dual-Mode Electrochemical Sensing of MicroRNA.

Oxide materials with redox properties have aroused growing interest in many applications. Introducing dopants into crystal lattices provides an effective way to optimize the catalytic activities of the oxides as well as their redox properties. Herein, CeO2 nanospheres codoped with Cu and Co (CuCo-CeO2 NSs) were first synthesized and exploited as efficient electrocatalysts for dual-mode electrochemical sensing of microRNA (miRNA). With the doping of Cu and Co into the CeO2 lattice, large amounts of extra oxygen vacancies were generated, remarkably enhancing the redox and electrocatalytic properties of the CeO2 material. The abundant oxygen vacancies of the CuCo-CeO2 NSs were further identified by X-ray photoelectron spectroscopy (XPS), H2 temperature-programmed reduction (H2-TPR), and electron-energy-loss spectroscopy (EELS). Moreover, Mg2+-induced DNAzyme-assisted target recycling was introduced for ultrasensitive determination. The dual-mode sensing with generality was conducted as follows: First, the CuCo-CeO2 NSs acted as a direct redox mediator to generate a differential-pulse-voltammetry (DPV) signal, which was then greatly amplified by the efficient electrocatalysis of CuCo-CeO2 NSs toward H2O2 decomposition. Second, under the electrocatalysis of CuCo-CeO2 NSs, 3,3-diaminobenzidine (DAB) was oxidized to form nonconductive insoluble precipitates (IPs), leading to great amplification of the electrochemical-impedimetric-spectroscopy (EIS) signal. The dual-mode electrochemical sensor showed a wide linear range (0.1 fM to 10 nM) with a low detection limit (33 aM), paving a new way for constructing ultrasensitive electrochemical sensors.

Synthesis of g-C3N4/N-doped CeO2 composite for photocatalytic degradation of an herbicide

In photocatalysis, surface engineered CeO2 could be vital due to oxygen vacancies arise from multiple valency, i.e. Ce3+ and Ce4+. This study reports photocatalytic properties of g-C3N4/CeO2 composite synthesized by a facile method in the presence of l-arginine. Physicochemical properties of g-C3N4/CeO2 material were analyzed through various characterization techniques such as XRD, UV–Vis, physisorption, etc., and correlated with its photocatalytic activity. Observed bandgap of the synthesized composite material was in the visible region, around 2.8eV which is less than that of typical ceria, but higher than bandgap of exfoliated g-C3N4. On the further side, N doping into CeO2 was confirmed through XPS analysis. It is estimated that synthesis method aided for the N doping, which further played key role in lowering the bandgap of g-C3N4/CeO2 composite. Finally, Photocatalytic activity of g-C3N4/CeO2 composite was analyzed through degradation of an herbicide i.e. diuron, and the study revealed the good performance of the catalyst.

Highly Active CeO2 Nanocatalysts for Low-Temperature CO Oxidation

Ceria (CeO2) nanocatalysts were synthesized by three different methods via a simple sol–gel method (SGM), precipitation method (PPM), and solution combustion method (SCM) for CO oxidation reaction. The results show that the CeO2 catalysts prepared by SGM possess small crystallite size (9 nm), more lattice defects (active sites), high specific surface area (188 m2 g–1), and better thermal stability. Raman spectra showed that large number oxygen vacancies were possessed by CeO2-SGM catalysts as compared to CeO2-PPM and CeO2-SCM. It was observed that the catalytic activity for CO oxidation reaction is greatly influenced by the preparation method. The order of activity and stability of CeO2 material prepared by different methods for CO oxidation process is as follows: CeO2-SGM > CeO2-PPM > CeO2-SCM, respectively.

Synthesis and characterization of a mesoporous cerium oxide catalyst for the conversion of glycerol

CeO2 mesoporous materials were synthesized employing the “hard and soft template” technique. Ceria catalysts have been prepared by a nanocasting procedure using SBA-15 and KIT-6 silica-based templates and Pluronic P123 and F127 for the “soft template” technique. The mesoporous CeO2 was characterized by techniques such as N2 physisorption, which confirmed a mesoporous size pore system and transmission electron microscopy, TEM, which confirmed the material ordered pore structure. TGA/DTA analysis was used to determine the loss of weight compared to the temperature before and after the elimination of the template. On the other hand, by means of IR spectroscopy of the Ce-KIT-6 material, the partial elimination of the Si template after the NaOH treatment was confirmed by decreasing the peaks corresponding to the vibration bands of the Si-O-Si linkages. Finally, by temperature-programmed desorption (TPD) of NH3 and CO2, the acid and basic strength of the catalysts were determined, respectively. All samples exhibited much higher total basicity relative to total acidity. The analysis of TPR-H2 showed regions of low temperature (350-400ºC) where the reduction of the bulk is plausible to be initiated and of high temperature (550ºC) of superficial reduction of the ceria.The performance of the catalysts was evaluated in the dehydration reaction of glycerol in gas phase at 320 ºC. The mesoporous CeO2 material was selective to acetol and reached a 100% conversion of glycerol. The catalyst prepared by the “soft template” technique (CeO2-P123) was the most selective to acetol (76%) with a 12% selectivity to acrolein. With the catalyst prepared by the “hard template” technique (Ce-KIT-6), the selectivity towards acetol was 48% and 22% towards acrolein. The acid properties of CeO2 were found to be a determining factor for the selectivity to acetol and acrolein.

UV-Resistant and Thermally Stable Superhydrophobic CeO2 Nanotubes with High Water Adhesion.

A novel type of sticky superhydrophobic cerium dioxide (CeO2 ) nanotube material is prepared by hydrothermal treatment without any chemical modification. A water droplet on the material surface shows a static water contact angle of about 157° but the water droplet is pinned on the material surface even when the material surface is turned upside down. Interestingly, the as-prepared CeO2 nanotube material displays durable superhydrophobicity and enhanced adhesion to water under ultraviolet (UV) light irradiation. Importantly, this change in water adhesion can be reversed by heat treatment to restore the original adhesive value of 20 µL. Further, the maximum volume of the water droplet adhered on the material surface of CeO2 nanotubes can be regulated without loss of superhydrophobicity during the heating treatment/UV-irradiation cycling. Meanwhile, the superhydrophobic CeO2 nanotube material shows remarkable thermal stability even at temperatures as high as 450 °C, long-term durability in chemical environment, and air-storage and good resistance to oily contaminant. Finally, the potential application in no-loss water transportation of this sticky superhydrophobic CeO2 material is demonstrated.

Effect of rare earth (RE – La, Pr, Nd) metal-doped ceria nanoparticles on catalytic hydrogen iodide decomposition for hydrogen production

In this work, high surface area rare earth (RE = La, Pr, and Nd) metal-doped ceria (CeO2) nanocatalysts have been synthesized by the citric-aided sol-gel method for hydrogen-iodide decomposition in thermochemical water-splitting sulfur-iodine (SI) cycle for hydrogen production. This sol-gel method allows the insertion of rare earth metal M3+ ions into the CeO2 material. Incorporation of rare earth metals created a different synergistic effect between RE and Ce components such as increase of oxygen mobility, oxygen vacancy, and thermal stability of the CeO2 material. These doped-CeO2 materials were characterized by various physicochemical techniques, namely, XRD, BET, ICP-AES, TEM, TGA, and RAMAN spectroscopy. XRD and TEM studies revealed 5–10 nm particles of the RE-CeO2 material. Shifting of peaks and increase in lattice parameter values confirmed the formation of Ce-RE solid solutions (XRD and Raman). Incorporation of dopants resulted in an increase in the specific surface area (BET), thermal stability (TGA), and oxygen vacancy concentration (Raman). Among different dopants, CeO2-L (La-doped CeO2) material exhibits the highest specific surface area, thermal stability, and oxygen vacancy concentration, and smallest crystallite size. The catalytic activity of doped-CeO2 materials is explored for hydrogen-iodide decomposition. The order of catalytic activity is as follows: CeO2 < CeO2-N (N = Nd) < CeO2-P (P = Pr) < CeO2-L (L = La). CeO2-L shows higher catalytic activity and stability in comparison to the pure CeO2 material. It also showed an excellent time-on-stream stability for 35 h. The apparent activation energy of CeO2-L, CeO2-P, and CeO2-N was found to be 48.9, 54.8, and 61.4 kJ mol−1, respectively. The effect of iodine on hydrogen iodide conversion was also studied over a CeO2-L catalyst. Thus, RE-doped CeO2 catalysts show a lot of potential of generating hydrogen from hydrogen iodide in the SI cycle.

The role of charge in the toxicity of polymer-coated cerium oxide nanomaterials to Caenorhabditis elegans

This study examined the impact of surface functionalization and charge on ceria nanomaterial toxicity to Caenorhabditis elegans. The examined endpoints included mortality, reproduction, protein expression, and protein oxidation profiles. Caenorhabditis elegans were exposed to identical 2–5nm ceria nanomaterial cores which were coated with cationic (diethylaminoethyl dextran; DEAE), anionic (carboxymethyl dextran; CM), and non-ionic (dextran; DEX) polymers. Mortality and reproductive toxicity of DEAE-CeO2 was approximately two orders of magnitude higher than for CM-CeO2 or DEX-CeO2. Two-dimensional gel electrophoresis with orbitrap mass spectrometry identification revealed changes in the expression profiles of several mitochondrial-related proteins and proteins that are expressed in the C. elegans intestine. However, each type of CeO2 material exhibited a distinct protein expression profile. Increases in protein carbonyls and protein-bound 3-nitrotyrosine were also observed for some proteins, indicating oxidative and nitrosative damage. Taken together the results indicate that the magnitude of toxicity and toxicity pathways vary greatly due to surface functionalization of CeO2 nanomaterials.

CeO2-Grafted Mn–Fe Oxide Composites as Alternative Oxygen-Storage Materials for Three-Way Catalysts: Laboratory and Chassis Dynamometer Tests

A CeO2-grafted MnFeOy (CeO2/MnFeOy) has been developed as a substitute for the oxygen-storage CeO2 material in three-way catalysts. In the CeO2/MnFeOy composite, CeO2 grains were intimately bound to the surface of the MnFeOy solid solution, which adopted an α-Mn2O3-type structure. Because the surface-grafted CeO2 acts as an oxygen gateway and MnFeOy acts as an oxygen reservoir, the combination of these oxides has a synergistic effect leading to the fast release and storage of a larger amount of oxygen compared with the separate constituents. The catalytic and oxygen release and storage performances of CeO2/MnFeOy were superior to those of CeO2/Fe2O3 in a previous study and were correlated to the contribution of Mn in the redox cycles. Finally, a real-sized honeycomb catalyst containing CeO2/MnFeOy was developed and tested using a vehicle driven on a chassis dynamometer in the JC08 (hot start) mode for gasoline engine vehicles (Japanese-type approval test cycle) and compared with a reference honeycomb cata...

Synthesis of biomimetic cerium oxide by bean sprouts bio-template and its photocatalytic performance

Biomimetic nano CeO2 materials were prepared by using bean sprouts as bio-template through impregnation and thermal decomposition. For characterization of structure, X-ray diffraction spectroscopy (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), UV-Vis diffuse reflectance spectra (UV-Vis/DRS) nitrogen adsorption-desorption measurements and Labsolar H2 system were adopted. The results demonstrated that the samples prepared at 550 °C not only completely removed the original bio-template, but also retained the morphology and microstructure of bean sprouts. Then the biomorphic structure of fluorite structure CeO2 material was obtained. Micro-pores with a diameter of about 2–3 nm were distributed among the particles, which provided more favorable channel for the photocatalytic reaction. Biomimetic CeO2 materials exhibited clear red shift (50 nm) compared with powder CeO2, which could be excited by visible irradiation. Biomimetic CeO2 materials displayed the superior photocatalytic activity for the hydrogen production by water splitting under the sunlight irradiation, the hydrogen yield could reach 400 μmol/g catalyst after 6 h.

Cross-beam pulsed laser fabrication of Free-Standing Nanostructured Carbon Nanotubes-Pt-Ceria Anode with unprecedented electroactivity and durability for ethanol oxidation

Owing to its inherent properties such as great capacity to store and release oxygen, lattice oxygen that has a key role in removing the CO poisoning effect, non-toxicity, abundance, low cost and low temperature processing, CeO2 is emerging as a unique class of electrode material for low temperature polymer electrolyte fuel cells such as direct ethanol fuel cells (DEFCs). However, the maximal exploitation of its functional properties is strictly reliant on the availability of optimized synthesis routes that allow tailor-designing, architecturing and manipulation of CeO2 in a precise manner when it is combined with other functional materials. Here we use the cross-beam pulsed laser deposition (CBPLD) technique to synthesize free-standing (binderless) Pt–CeO2 nanostructured thin films onto carbon nanotubes as anodes for ethanol oxidation reaction. Further significance of this work is that it establishes the importance in the design of the catalyst layer architecture. Indeed, we demonstrate here that when CeO2 material is beneath or when it is mixed with Pt, the interactions between Pt with CeO2 are not similar leading inevitably to different electrocatalytic performances. Given proper tailoring synthesis conditions, CBPLD-developed Pt–CeO2 thin films are remarkably stable and provide electrochemical performance much greater than the layer onto layer CeO2/Pt architecture.

Electrical and microstructural properties of Yb-doped CeO2

Nanopowdered Ce1−xYbxO2−δ solid solutions (0 ≤ x ≤ 0.2) were synthesized by a self-propagating room temperature synthesis. XRD and SEM were used to study the properties of these materials as well as the Yb solubility in CeO2 lattice. Results showed that all the obtained powders were solid solutions with a fluorite-type crystal structure and with nanometric particle size. The average size of Ce1−xYbxO2−δ particles was approximately 3 nm. Electrochemical impedance spectroscopy for the sintered pellets depicted that it was possible to separate Rbulk and Rgb in the temperature interval of 550–800 °C. The activation energy for the bulk conduction was 1.03 eV and for grain boundary conduction was 1.14 eV. Grain boundary resistivity dominates over the other resistivities. These measurements confirmed that Yb3+-doped CeO2 material had a potential as electrolyte for intermediate-temperature solid oxide fuel cell applications.