Vibrational Frequencies of Cerium-Oxide-Bound CO: A Challenge for Conventional DFT Methods

  • chair:

    Lustemberg, P. G. / Plessow, P. N. / Wang, Y. / Yang, C. / Nefedov, A. / Studt, F. / Wöll, C. / Ganduglia-Pirovano, M. V. (2020)

  • place:

    Phys. Rev. Lett. 125, 256101 – Published 17 December 2020; Erratum Phys. Rev. Lett. 128, 019901 (2022)

  • Date: Dezember 2020
  • Abstract

    In ceria-based catalysis, the shape of the catalyst particle, which determines the exposed crystal facets, profoundly affects its reactivity. The vibrational frequency of adsorbed carbon monoxide (CO) can be used as a sensitive probe to identify the exposed surface facets, provided reference data on well-defined single crystal surfaces together with a definitive theoretical assignment exist. We investigate the adsorption of CO on the CeO2(110) and (111) surfaces and show that the commonly applied DFT(PBE)+U method does not provide reliable CO vibrational frequencies by comparing with state-of-the-art infrared spectroscopy experiments for monocrystalline CeO2 surfaces. Good agreement requires the hybrid DFT approach with the HSE06 functional. The failure of conventional density-functional theory (DFT) is explained in terms of its inability to accurately describe the facet- and configuration-specific donation and backdonation effects that control the changes in the C─O bond length upon CO adsorption and the CO force constant. Our findings thus provide a theoretical basis for the detailed interpretation of experiments and open up the path to characterize more complex scenarios, including oxygen vacancies and metal adatoms