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Influence of Cerium Precursor on the Size and Solid Solubility of Transition Metals in Combustion Synthesized $Ce_1_-_xM_xO_2_-_d$ (M = Cu, Pd) Nano Crystallites: Enhancement of Redox Properties and Catalytic Activity

Gayen, Arup and Baidya, Tinku and Prakash, AS and Ravishankar, N and Hegde, MS (2005) Influence of Cerium Precursor on the Size and Solid Solubility of Transition Metals in Combustion Synthesized $Ce_1_-_xM_xO_2_-_d$ (M = Cu, Pd) Nano Crystallites: Enhancement of Redox Properties and Catalytic Activity. In: Indian Journal of Chemistry Section A- Inorganic Bio-Inorganic Physical, 44 (1). pp. 34-48.

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Abstract

Two cerium precursors have been employed to synthesize $Ce_1_-_xM_xO_2_d (M = Cu, Pd) $ nano-crystalline catalysts by solution combustion method.These nano materials have been characterized by X-ray diffraction(XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and BET surface area measurement. Redox behaviour ofthe catalysts was investigated by temperature-programmed reduction $(H_2TPR)$. Use of ceric ammonium nitrate (precursor A) gives ceria crystallites of size 30-45 nm while cerrous nitrate (precursor B) gives 10-15 nm sized crystallites indicating three fold decrease in crystallite size of $CeO_2$. Solid solubility of copper in $CeO_2$ matrix is between 5-10 atom % with precursor A and it increases to 10-15 atom % with precursor B. The crystallite size is between 15-20 urn using B precursor compared to 40-50 nm crystallites with precursor A when Pd was substituted for Ce indicating approximately a two-fold decrease. With precursor A, solid solubility of Pd in ceria is between 3-5 atom% which increases to similar to 10 atom % with precursor B. Structural study shows $M^2^+ ion$ substitution into $C_eO_2$, matrix. The enhancement of solid solubility coupled with the decrease in crystallite size is associated with an increase in oxygen storage capacity and catalytic activity for CO oxidation by $0_2$, and NO reduction by CO. Such anapproach to synthesis of transition metal ion substituted nano $CeO_2$, is leading to catalysts with higher catalytic activity.

Item Type: Journal Article
Additional Information: The copyright for this article belongs to National Institute for Science Comminication.
Department/Centre: Division of Chemical Sciences > Materials Research Centre
Division of Chemical Sciences > Solid State & Structural Chemistry Unit
Date Deposited: 01 Mar 2005
Last Modified: 20 Jan 2012 06:00
URI: http://eprints.iisc.ernet.in/id/eprint/2835

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