Sol-Gel-Derived Ceria Nanoarchitectures: Synthesis, Characterization, and Electrical Properties

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• 作者：Christel Laberty-Robert ; Jeffrey W. Long ; Erik M. Lucas ; Katherine A. Pettigrew ; Rhonda M. Stroud ; Michael S. Doescher ; and Debra R. Rolison
• 刊名：Chemistry of Materials
• 出版年：2006
• 出版时间：January 10, 2006
• 年：2006
• 卷：18
• 期：1
• 页码：50 - 58
• 全文大小：494K
• 年卷期：v.18,no.1(January 10, 2006)
• ISSN：1520-5002

文摘

Nanocrystalline ceria is under study to improve performance in high-temperature catalysis and fuelcells. We synthesize porous ceria monolithic nanoarchitectures by reacting Ce(III) salts and epoxide-based proton scavengers. Varying the means of pore-fluid removal yields nanoarchitectures with differentpore-solid structures: aerogels, ambigels, and xerogels. The dried ceria gels are initially X-ray amorphous,high-surface-area materials, with the aerogel exhibiting 225 m² g^-1. Calcination produces nanocrystallinematerials that, although moderately densified, still retain the desirable characteristics of high surfacearea, through-connected porosity in the mesopore size range and nanoscale particle sizes (~10 nm). Theelectrical properties of calcined ceria ambigels are evaluated from 300 to 600 mages/entities/deg.gif">C and compared to thoseof commercially available nanoscale CeO₂. The pressed pellets of both ceria samples exhibit comparablesurface areas and void volumes. The conductivity of the ceria ambigel is 5 times greater than thecommercial sample and both materials exhibit an increase in conductivity in argon relative to oxygen at600 mages/entities/deg.gif">C, suggesting an electronic contribution to conductivity at low oxygen partial pressures. The ceriaambigel nanoarchitecture responds to changes in atmosphere at 600 mages/entities/deg.gif">C faster than does the nanocrystalline,non-networked ceria. We attribute the higher relative conductivity of CeO₂ ambigels to the bondedpathways inherent to the bicontinuous pore-solid networks of these nanoarchitectures.