Reassignment of the Vibrational Spectra of Carbonates, Formates, and Related Surface Species on Ceria: A Combined Density Functional and Infrared Spectroscopy Investigation

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• 作者：Georgi N. Vayssilov ; Mihail Mihaylov ; Petko St. Petkov ; Konstantin I. Hadjiivanov ; Konstantin M. Neyman
• 刊名：Journal of Physical Chemistry C
• 出版年：2011
• 出版时间：December 1, 2011
• 年：2011
• 卷：115
• 期：47
• 页码：23435-23454
• 全文大小：1889K
• 年卷期：v.115,no.47(December 1, 2011)
• ISSN：1932-7455

文摘

Using a combination of state-of-the-art computational modeling and Fourier transform infrared (FTIR) spectroscopy study of the surface species formed during interaction of CO₂ or CO with activated (stoichiometric), reduced, and hydroxylated ceria, CeO₂, we assigned various experimentally observed vibrational modes to individual types of surface species. We considered carbonates CO₃^{2鈥?/sup>, formates HCO₂鈥?/sup>, and hydrogen carbonates CO₂(OH)鈭?/sup> bound in various ways to the surface of a ceria nanoparticle. Since the structure of the surface carbonate species is particularly versatile, we introduced a notation of different types of such species and computationally determined the regions where the characteristic vibrational frequencies of each type of species can be found. The complementary FTIR measurements of the surface species produced under different conditions revealed the actual experimental vibrational peaks and allowed estimation of the accuracy of the computational method to reproduce the frequencies of different vibrational modes. Thus, combining computed and experimental data we suggest a sound, partly new assignment of the vibrational bands in the complex IR spectra of surface (hydrogen)carbonate and formate species on ceria. The proposed reassignment of the vibrational peaks enables reliable detection of the surface species on ceria surface using vibrational spectroscopy. This is critical for the meaningful analysis of the reactivity of these species and the clarification of the mechanisms of the rich variety of surface processes on ceria.}