Cerium-doped zirconias

Domenech, A., Aucejo, R., Alarcon, J., and Navarro, P. 2004b. Electrocatalysis of the oxidation of methylenedioxyamphetamines at electrodes modified by cerium-doped zirconias. Electrochemistry Communications 6, 719-723. 

The addition of cerium oxide, for example, to zirconia produces a material with exceptional toughness and good strength [29], Cerium oxide-doped zirconia is used also in thermal barrier spray coatings on metal surfaces(30]. 

Chiral electrocatalysis can be achieved via formation of chiral surfaces (Attard, 2001 Pleus and Schulte, 2001 Hazzazi et al., 2004) but also by inserting chiral centers into the inorganic matrix. This should apply to the case of monoclinic and cerium- and vanadium-doped zirconias (Domenech and Alarcon, 2007), which will be presented in Chapter 9. 

Yttria-doped( 20 mol% Y2O3) cerium oxide also has a higher 0 ion conductivity than yttria-stabilized zirconia ( factors of 11-18 at 600°C), which would make it an attractive choice for an electrolyte at lower temperatures (< 800 C) However, doped cerium oxides tend to undergo reduction, with formation of trivalent cerium ions and oxygen ion vacancies, V 6 leading to the onset of electronic conductivity according to ... 

Complex FCC oxides of the fluorite type represent oxygen-conduction solid electrolytes (SOE s). They comprise a typical class of materials for the manufacture of sensors of oxygen activity in complex gas mixtures, oxygen pumps, electrolyzers and high-temperature fuel elements. These materials are based on doped oxides of cerium and thorium, zirconium and hafnium, and bismuth oxide. Materials based on zirconium oxide, for example, yttrium stabilized zirconia (YSZ) are the most known and studied among them. This fact is explained both by their processibility and a wide spectrum of practical applications and by the possibility to conduct studies on single crystals, which have the commercial name "fianites" and are used in jewelry. 

Recently, sulfated zirconia aerogels were also doped with cerium. In order to optimize the catalytic performances of these materials, prepared by the sol-gel method, Mejri et al. [48] studied the impact of the solvent evacuation mode on their properties. The xerogel solids (XZC) obtained by ordinary gel drying and calcined at different temperatures exhibit a very low surface areas. On the contrary, the aerogels (AZC) obtained by solvent evacuation under supercritical conditions show a more developed surface areas (Table 6.2). 

Table 6.3. Activity and selectivity of aerogel- and xerogeZ-sulfated zirconia doped with cerium in n-hexane isomerization reaction [48]...

Mejri I, Younes M K, Ghorbel A, Eloy P, Gaigneaux E M (2008) Effect of the evacuation mode of solvent on the textural, structural and catalytic properties of sulfated zirconia doped with cerium. Stud Surf Sci Catal 174 493 96... 

Attenuation length A (optical) The distance traveled across in an aerogel, where the probability that a photon has not been absorbed has dropped by 1/e (where e = 2.71828) AZC Aerogel sulfated zirconia doped with cerium AZS Aerogel sulfated zirconia... 

Xylan Generic term for complex polysaccharides XZC Xerogel Sulfated Zirconia doped with Cerium... 

Vanadium oxide and cerium oxide have also been used to dope titania-zirconia mixed oxides. Their results will be discussed in the next section. 

Titania-zirconia mixed oxides doped with vanadium and cerium oxides were also explored. The Ti02-Zr02 mixed oxide support, synthesized by a co-precipitation... 

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