Correlating DFT Calculations with CO Oxidation Reactivity on Ga-Doped Pt/CeO2 Single-Atom Catalysts

Pt/CeO2 single-atom catalysts have recently attracted increasing interest due to excellent thermal stability, high atom efficiency, and high activity in catalysis. In this study, by means of density functional theory (DFT) calculations, we systematically compare the stability and CO oxidation reactivity of Pt single atoms supported on CeO2 (111) (Pt/CeO2) and Ga-doped CeO2 (111) (Pt/Ga- CeO2). It was found that the formation of an oxygen vacancy (O-v) is very facile near a surface Ga-doping site (Pt/Ga-CeO2-O-v). Significantly, the stability of Pt single atoms anchored on the Ga site was enhanced compared with those on the bare ceria surface. In addition, our DFT results suggest a CO oxidation mechanism on Pt/Ga-CeO2-O-v that differs from that on Pt/CeO2. In particular, the O-v site plays an important role in activating the oxygen molecule, which then reacts with CO preadsorbed on Pt. The calculated energy barrier on Pt/Ga-CeO2-O-v is about 0.43 eV lower than that on the undoped catalyst, suggesting an enhanced reactivity for CO oxidation. Experiments on CO oxidation and in situ diffuse reflectance infrared Fourier transform spectroscopy are performed to corroborate the results obtained from the DFT calculations, and a good agreement is achieved. The combination between calculations and experiments sheds light on the influence of support doping on atomically dispersed Pt/CeO(2 )catalysts.