Reactions of Methanol with Pristine and Defective Ceria (111) Surfaces: A Comparison of Density Functionals

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• 作者：Thomas Kropp ; Joachim Paier
• 刊名：Journal of Physical Chemistry C
• 出版年：2014
• 出版时间：October 16, 2014
• 年：2014
• 卷：118
• 期：41
• 页码：23690-23700
• 全文大小：359K
• ISSN：1932-7455

文摘

We study the dissociative adsorption and oxidative dehydrogenation of methanol at the pristine and O-defective ceria (111) surfaces to understand the role of surface oxygen vacancies. The accuracy of two density functional theory based approaches (PBE+U and the HSE hybrid functional) is assessed on available experimental data. In addition, the impact of dispersion correction and zero-point vibrational energy contributions is discussed. Calculated vibrational frequencies are compared with experimental IR spectra. Using dispersion-corrected PBE+U, we obtain comparably large intrinsic barriers for the oxidation step at the pristine (104 kJ/mol) and defective (119 kJ/mol) ceria surfaces. Compared to HSE+D, these barriers are underestimated by 20 kJ/mol. Adsorption energies for the pristine surface agree well between PBE+U+D (鈭?8 kJ/mol) and HSE+D (鈭?6 kJ/mol). However, adsorption energies for the defective surface vary by 25 kJ/mol (PBE+U+D: 鈭?31 kJ/mol; HSE+D: 鈭?06 kJ/mol). Nonetheless, adsorption into surface oxygen defects is thermodynamically highly favored. As a result, oxygen vacancies are preferred active sites for methanol oxidation in temperature-programmed desorption experiments.