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Jurado, J. R.

doi:10.1023/a:1004873623892

Cited by 62 publications

(22 citation statements)

References 13 publications

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“…Ceria plays multiple roles in various catalyst systems and it is believed that CeO 2 promotes noble metal dispersion, increases thermal stability of Al 2 O 3 support, promotes water gas shift (WGS) and steam reforming reactions, favors catalytic activity at the interfacial metal-support sites, promotes CO removal through oxidation by employing its lattice oxygen, stores and releases oxygen (OSC) under lean and rich conditions, and so on [4]. Therefore, CeO 2 containing materials have been receiving a great deal of attention in recent years due to their extensive use in very broad fields, ranging from catalysis [1][2][3][4][5][6][7] to ceramics [8], fuel cell technologies [9][10][11], gas sensors [12,13], solid state electrolytes [14], chromatographic materials [15], cosmetics, etc [16,17]. The technological applicability of CeO 2 -containing materials is expanding very rapidly.…”

Section: Introductionmentioning

confidence: 99%

Nanosized CeO2–SiO2, CeO2–TiO2, and CeO2–ZrO2 Mixed Oxides: Influence of Supporting Oxide on Thermal Stability and Oxygen Storage Properties of Ceria

2005

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The influence of SiO 2 , TiO 2 , and ZrO 2 on the structural and redox properties of CeO 2 were systematically investigated by various techniques namely, X-ray diffraction (XRD), Raman spectroscopy (RS), UV-Vis diffuse reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HREM), BET surface area, and thermogravimetry methods. The effect of supporting oxides on the crystal modification of ceria was also mainly focused. The investigated oxides were obtained by soft chemical routes with ultrahigh dilute solutions and were subjected to thermal treatments from 773 to 1073 K. The XRD results suggest that the CeO 2 -SiO 2 sample primarily consists of nanocrystalline CeO 2 on the amorphous SiO 2 surface. Both crystalline CeO 2 and TiO 2 -anatase phases were noted in the case of CeO 2 -TiO 2 sample. Formation of cubic Ce 0.75 Zr 0.25 O 2 and Ce 0.6 Zr 0.4 O 2 (at 1073 K) were observed in the case of CeO 2 -ZrO 2 sample. The cell 'a' parameter estimations revealed an expansion of the ceria lattice in the case of CeO 2 -TiO 2 , while a contraction is noted in the case of CeO 2 -ZrO 2 . The DRS studies suggest that the supporting oxides significantly influence the band gap energy of CeO 2 . Raman measurements disclose the presence of oxygen vacancies, lattice defects, and displacement of oxide ions from their normal lattice positions in the case of CeO 2 -TiO 2 and CeO 2 -ZrO 2 samples. The XPS studies revealed the presence of silica, titania, and zirconia in their highest oxidation states, Si(IV), Ti(IV), and Zr(IV) at the surface of the materials. Cerium is present in both Ce 4+ and Ce 3+ oxidation states. The HREM results reveal well-dispersed CeO 2 nanocrystals over the amorphous SiO 2 matrix in the case of CeO 2 -SiO 2 , isolated CeO 2 and TiO 2 (A) nanocrystals and some overlapping regions in the case of CeO 2 -TiO 2 , and nanosized CeO 2 and Ce-Zr oxides in the case of CeO 2 -ZrO 2 sample. The exact structural features of these crystals as determined by digital diffraction analysis of HREM experimental images reveal that the CeO 2 is mainly in cubic fluorite geometry. The oxygen storage capacity (OSC) as determined by thermogravimetry reveals that the OSC of mixed oxides is more than that of pure CeO 2 and the CeO 2 -ZrO 2 exhibits highest OSC.

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Section: Introductionmentioning

confidence: 99%

Nanosized CeO2–SiO2, CeO2–TiO2, and CeO2–ZrO2 Mixed Oxides: Influence of Supporting Oxide on Thermal Stability and Oxygen Storage Properties of Ceria

2005

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“…Ceria is a key component in three-way catalysts (TWC) and a base material for electrolytes and electrodes in solid oxide fuel cells (SOFCs) [1,2]. Apart from these applications, ceria has also been extensively employed in low temperature water-gas-shift reaction [12], production and purification of hydrogen [13], ceramics [14], fuel cell technologies [15][16][17], gas sensors [18,19], solid state electrolytes [20], chromatographic materials [21], cosmetics, and so on [22,23]. Nanostructured CeO 2 can impact significantly in all these practical applications due to an improvement in the physicochemical properties such as thermal stability and redox property with respect to the bulk like materials.…”

Section: Introductionmentioning

confidence: 99%

Highly Dispersed Ce x Zr1−x O2 Nano-Oxides Over Alumina, Silica and Titania Supports for Catalytic Applications

2008

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We have been exploring the utilization of supported ceria and ceria-zirconia nano-oxides for different catalytic applications. In this comprehensive investigation, a series of Ce x Zr 1-x O composite oxide catalysts were synthesized and subjected to thermal treatments from 773 to 1073 K to examine the influence of support on thermal stability, textural properties and catalytic activity of the ceria-zirconia solid solutions. The physicochemical characterization studies were performed using X-ray diffraction (XRD), Raman spectroscopy (RS), X-ray photoelectron spectroscopy (XPS), and high-resolution transmission electron microscopy (HREM), thermogravimetry and BET surface area methods. To evaluate the catalytic properties, oxygen storage/release capacity (OSC) and CO oxidation activity measurements were carried out. The XRD analyses revealed the formation of Ce 0.75 Zr 0.25 O 2 , Ce 0.6 Zr 0.4 O 2 , Ce 0.16 Zr 0.84 O 2 and Ce 0.5 Zr 0.5 O 2 phases depending on the nature of support and calcination temperature employed. Raman spectroscopy measurements in corroboration with XRD results suggested enrichment of zirconium in the Ce x Zr 1-x O 2 solid solutions with increasing calcination temperature thereby resulting in the formation of oxygen vacancies, lattice defects and oxygen ion displacement from the ideal cubic lattice positions. The HREM results indicated a well-dispersed cubic Ce x Zr 1-x O 2 phase of the size around 5 nm over all supports at 773 K and there was no appreciable increase in the size after treatment at 1073 K. The XPS studies revealed the presence of cerium in both Ce 4? and Ce 3? oxidation states in different proportions depending on the nature of support and the treatment temperature applied. All characterization techniques indicated absence of pure ZrO 2 and crystalline inactive phases between Ce-Al, Ce-Si and Ce-Ti oxides. Among the three supports employed, silica was found to stabilize more effectively the nanosized Ce x Zr 1-x O 2 oxides by retarding the sintering phenomenon during high temperature treatments, followed by alumina and titania. Interestingly, the alumina supported samples exhibited highest OSC and CO oxidation activity followed by titania and silica. Details of these findings are consolidated in this review.

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“…One major issue in the improvement of the performance of lower temperature SOFCs is the development of a solid oxide electrolyte (SOE) with sufficiently high ionic conductivity [4,5]. Alternative SOEs, such as samariadoped ceria (SDC) and erbia-stabilized bismuth oxide (ESB), have been suggested because their conductivity is one to two orders of magnitude higher than that of current yttria-stabilized zirconia (YSZ) electrolytes [6,7].…”

Section: Introductionmentioning

confidence: 99%

Stable and high conductivity ceria/bismuth oxide bilayer electrolytes for lower temperature solid oxide fuel cells

Park

Wachsman

2006

Ionics

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A highly conductive bismuth oxide/ceria bilayer electrolyte was developed to reduce solid oxide fuel cell (SOFC) operating temperatures. Bilayer electrolytes were fabricated by depositing a layer of Er 0.2 Bi 0.8 O 1.5 (ESB) of varying thickness via pulsed laser deposition and dip-coating on a Sm 0.2 Ce 0.8 O 1.9 (SDC) substrate. The open-circuit potential (OCP) and ionic transference number (t i ) of ESB/ SDC electrolytes were tested in a fuel cell arrangement as a function of relative thickness, temperature, and P O 2 with H 2 / H 2 O and CO/CO 2 on the anode side and air on the cathode side. These EMF measurements showed a significant increase in OCP and t i with the bilayer structure, as compared to the cells with a single SDC electrolyte layer. Furthermore, improvement in the OCP and t i of bilayer SOFCs was observed with increasing relative thickness of the ESB layers. Hence, the bilayer structure overcomes the limited thermodynamic stability of bismuth oxides and prevents electronic conductivity of ceria-based oxides in reducing atmosphere.

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Cited by 62 publications

References 13 publications

Nanosized CeO2–SiO2, CeO2–TiO2, and CeO2–ZrO2 Mixed Oxides: Influence of Supporting Oxide on Thermal Stability and Oxygen Storage Properties of Ceria

Nanosized CeO2–SiO2, CeO2–TiO2, and CeO2–ZrO2 Mixed Oxides: Influence of Supporting Oxide on Thermal Stability and Oxygen Storage Properties of Ceria

Highly Dispersed Ce x Zr1−x O2 Nano-Oxides Over Alumina, Silica and Titania Supports for Catalytic Applications

Stable and high conductivity ceria/bismuth oxide bilayer electrolytes for lower temperature solid oxide fuel cells

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