Adsorption properties of noble-metal (Ag, Rh, or Au)-doped CeO2(1 1 0) to CO: A DFT + U study

Dissolved gas analysis (DGA) is an effective method for fault detection of oil-immersed transformers, and CO is one of the characteristic gases in insulation oil. Therefore, based on density functional theory, the adsorption properties of three noble metals (Ag, Rh, or Au)-doped CeO2 (1 1 0) to CO were studied in this paper. The adsorption energy, charge transfer, density of states (DOS), and deformation charge density (DCD) were calculated to analyze the adsorption behavior of CO on the material surface. The frontier molecular orbital, energy band structure, and desorption time were also calculated to evaluate the potential of the three doping systems as CO sensors. The results show that the adsorption properties of Ag-CeO2, Rh-CeO2, and Au-CeO2 to CO are significantly higher than that of pristine CeO2, with adsorption energies are −54.61, −85.78, −205.57 kJ/mol, respectively. However, Rh-CeO2 exhibits superior sensitivity and satisfactory recovery time towards CO compared with Ag-CeO2 and Au-CeO2. Rh-CeO2 also shows excellent selectivity to CO, which is a promising candidate material for CO sensors. The research conducted in this work is intended to contribute to dissolved gas analysis (DGA).