Vibrational frequencies of CO bound to all three low-index cerium oxide surfaces: A consistent theoretical description of vacancy-induced changes using density functional theory

The facet-dependent adsorption of CO on oxidized and reduced CeO2 single crystal surfaces is reviewed, with emphasis on the effect of CO coverage and the ability of state-of-the-art quantum-mechanical methods to provide reliable energies and an accurate description of the IR vibrational frequency of CO. Comparison with detailed, high-resolution experimental infrared reflection absorption spectroscopy data obtained for single crystal samples allows the assignment of the different CO vibrational bands observed on all three low-index ceria surfaces. Good agreement is achieved with the hybrid density functional theory approach with the HSE06 functional and with saturation coverage. It is shown that CO is very sensitive to the structure of cerium oxide surfaces and to the presence of oxygen vacancies. The combined theoretical-experimental approach offers new opportunities for a better characterization of ceria nanoparticles and for unraveling changes occurring during reactions involving CO at higher pressures.

Automated summary

This review focuses on the adsorption of CO on oxidized and reduced CeO2 single crystal surfaces, specifically examining CO coverage and the accuracy of quantum-mechanical methods in describing the IR vibrational frequency of CO. By comparing with experimental data, the study successfully assigns the CO vibrational bands observed on these surfaces. The results show that CO adsorption is greatly influenced by the surface structure and the presence of oxygen vacancies in cerium oxide.