CO adsorption on CeO2(1Â 1Â 0) using hybrid-DFT embedded-cluster calculations

The adsorption of CO on the CeO2(1 1 0) surface has been studied using hybrid density functional theory (DFT) in the form of the B3LYP functional. In our calculations, both physisorption and chemisorption are observed. In the physisorption case, CO binds perpendicularly to a surface Ce ion. The adsorption energy is estimated to 0.1 eV and the CO stretching vibration becomes slightly blue-shifted (+9 cm−1), but the changes to the substrate and adsorbate structure are minimal. Test calculations using Møller-Plesset perturbation theory to the second order (MP2) suggest that dispersive interactions may be important in the case of CO physisorption on ceria. A chemisorption site was also found, where the CO molecule binds to two surface O ions, forming a surface carbonate species. Here, B3LYP predicts an adsorption energy of 2.1 eV and a red-shift of 470 cm−1 for the CO stretching vibration.