Synthesis of CeO2-based core/shell nanoparticles with high oxygen storage capacity

Aytekin Uzunoglu,Dursun Ali Kose,Lia A Stanciu

doi:10.1007/s40089-017-0213-3

Aytekin Uzunoglu, Dursun Ali Kose + Show 1 more

Open Access

https://doi.org/10.1007/s40089-017-0213-3

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Abstract

Ceria plays a key role in various applications including sensing and catalysis owing to its high oxygen storage capacity (OSC). The aim of this work is to prepare novel MOx/CeO2 (M: Zr, Ti, Cu) metal oxide systems with core/shell structures using a facile two-step chemical precipitation method. The synthesized nanoparticles were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), and N2 adsorption methods. The OSC property of the samples was evaluated using TGA analysis conducted at 600 °C under reductive (5% H2/Ar) and oxidative (synthetic air) environments. The OSCs of the samples were found to be 130, 253, and 2098 µmol-O2/g for ZrO2/CeO2, TiO2/CeO2, and CuO/CeO2, respectively. Effects of heat treatment on the physical and redox properties of the samples were also evaluated. In this regard, the samples were exposed to 500 °C for 5 h under ambient environment. It was observed that the heat treatment induced the formation of mixed metal oxide alloys and the BET surface area of the samples diminished significantly. The OSC of the samples, however, did not experience any significant chance, which was attributed to the compensation of the loss in the surface area by the alloy formation after the heat treatment.

Highlights

Ceria (CeO2) and ceria-based nanomaterials have attracted great deal of interest for many applications ranging from cosmetic and sensing to catalysis due to their high redox properties [1,2,3,4,5]
MOx nanoparticles used as core in the core–shell structure was prepared via a chemical precipitation method conducted at room temperature
The X-ray diffraction (XRD) patterns of TiO2/CeO2 and CuO/CeO2 core/shell metal oxide systems revealed the presence of rutile TiO2 and monoclinic CuO phases, respectively

Summary

Introduction

Ceria (CeO2) and ceria-based nanomaterials have attracted great deal of interest for many applications ranging from cosmetic and sensing to catalysis due to their high redox properties [1,2,3,4,5]. The high redox property of CeO2, which is called as oxygen storage capacity (OSC), originates from the capability of binding O2 reversibly by shifting from Ce3+ to Ce4+ states under oxygen-rich and oxygenlean environments, respectively [3, 6]. Its high OSC property makes CeO2-based materials one of the key components in three-way catalysts in the automotive industry. It is known that the exhaust gas has fluctuations in O2 content and the concentration of O2 in the gas stream goes down and up, resulting from deviations in the stoichiometric air/fuel ratio. The use of CeO2-based materials in threeway catalyst systems as a promoter ensures the maintenance of the air/fuel stoichiometry by acting as oxygen buffer under the mentioned conditions. The reversible oxygen release and uptake property of CeO2 is shown in Eq 1 [8]

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