Pablo G. Lustemberg^1*, Chengwu Yang^2,3, Yuemin Wang⁴, M. Veronica Ganduglia-Pirovano¹, Christof Wöll⁴

1 Institute of Catalysis and Petrochemistry, CSIC, 28049 Madrid, Spain

2 State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan 030001, China

3 School of Energy and Power Engineering, Beihang University, Beijing 100191, China

4 Institute of Functional Interfaces, IFG, Karlsruhe Institute of Technology, KIT, 76344 Eggenstein-Leopoldshafen, Germany

* Corresponding authors emails: p.lustemberg@csic.es

DOI10.24435/materialscloud:cc-jr [version v1]

Publication date: Jan 28, 2025

How to cite this record

Pablo G. Lustemberg, Chengwu Yang, Yuemin Wang, M. Veronica Ganduglia-Pirovano, Christof Wöll, Synergistic effects in low-temperature CO oxidation on cerium oxide surfaces, Materials Cloud Archive 2025.21 (2025), https://doi.org/10.24435/materialscloud:cc-jr

Description

The mechanisms underlying the reaction between carbon monoxide (CO) and activated dioxygen on metal oxide substrates to produce CO₂ remain poorly understood, particularly regarding the role of oxygen vacancies and the nature of the activated O₂ adsorbate. In this study, we present experimental findings from infrared reflection-absorption spectroscopy on a model system of bulk monocrystalline CeO₂(111). Contrary to expectations, exposing the reduced surface to dioxygen (O₂) at 80 K does not yield activated oxygen species, such as superoxo or peroxo. Notably, in the presence of adsorbed CO, an unexpected low-temperature oxidation reaction occurs, consuming CO while oxidizing the CeO₂ substrate. Since a direct reaction between impinging O₂ and adsorbed CO is unlikely at these low temperatures, a novel mechanism is proposed. Extensive spin-polarized density functional theory (DFT) calculations reveal that oxygen vacancies play a critical role in this low-temperature CO oxidation. Initially located in the subsurface region (Vss), these vacancies migrate to the surface (Vs) via a concerted interaction with coadsorbed CO and O₂, leading to O₂ activation and the formation of superoxo or peroxo species. Detailed analysis identifies key reaction intermediates and quantifies their adsorption energies and activation barriers. Our findings suggest that the peroxo-mediated pathway, with its lower activation barrier, is more favorable for CO oxidation at low temperatures compared to the carbonate pathway. This study provides valuable insights into the dynamic role of subsurface oxygen vacancies in the activation of gaseous O₂ and CO oxidation mechanisms on CeO₂.

Materials Cloud sections using this data

Files

File name	Size	Description
README.txt MD5md5:ba64fe2a1ef89976fd656adca864fbec	3.0 KiB	Readme file
fig3.zip MD5md5:42a235cb0152ff0bcf00ec74752fe8bd	15.2 MiB	Reaction path for the oxidation of CO to CO2 via the CO3 intermediate. The states a to g correspond to the intermediates along the reaction pathway.
fig4.zip MD5md5:c9711a1844b646478f1c0c30d0cc07e2	3.1 MiB	O2 adsorption on CeO2−x(111) surfaces with (a-b) Vss and (c-d) Vs oxygen vacancies, and (f) Superoxo@Vss-II shown in (b) with co-adsorbed CO.
fig5.zip MD5md5:b083672a84830c1804493ddb71071bab	15.7 MiB	Reaction pathway for the oxidation of CO to CO2 via the intermediate O22⁻ species.
figS3.zip MD5md5:3e92e667fb01eb86eb67bd00a42603e6	25.9 MiB	Reaction path for the oxidation of CO to CO2 via the CO3 intermediate. The states a to g correspond to the intermediates along the reaction pathway.
references.zip MD5md5:7f19840f75d8cb9821727c06d72575aa	260.0 KiB	Contains calculations for gas-phase molecules (CO2, CO, O2) and CeO2−x surfaces with a subsurface oxygen vacancy and 2x2 periodicity.

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Keywords

CO oxidation Ceria Peroxo and Superoxo DFT