Time-resolved in situ UV/vis spectroscopy for analyzing the dynamics of surface and bulk redox processes in materials used as oxygen storage capacitors

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• 作者：Evgenii V. Kondratenko^a ; ^{evgenii.kondratenko@catalysis.de"" rel=""nofollow} ; Yoshiyuki Sakamoto^b ; Kohei Okumura^b ; Hirofumi Shinjoh^b
• 关键词：Oxygen storage capacity ; Dynamics ; Redox ; UV/vis analysis ; Platinum ; Ceria
• 刊名：Catalysis Today
• 出版年：2011
• 出版时间：30 April 2011
• 年：2011
• 卷：164
• 期：1
• 页码：46-51
• 全文大小：412 K

文摘

Time-resolved UV/vis-DR (diffuse reflectance UV/vis) spectroscopy was used to in situ monitor the dynamics of reduction and reoxidation of Pt-free and Pt-containing CeO₂–ZrO₂ used as oxygen storage capacitors. This method can be also applied for measuring the speed of oxygen release. Combining the spectroscopic catalyst characterization with transient reaction analysis (alternating feeding of CO(H₂) and O₂) enabled us to identify factors determining surface and bulk redox processes of ceria. The presence of Pt increased strongly the mobility and availability of lattice oxygen in CeO₂–ZrO₂ for oxygen release reactions, while the presence of strongly polymerized CeO_x species (non-homogeneous distribution of ZrO₂ in CeO₂) decreased the mobility of lattice oxygen. The results of the present in situ UV/vis-DR analysis support previous non-directly derived conclusions.