A Density Functional Theory Study Of Small Au Nanoparticles At CeO₂ Surfaces

Density functional theory calculations corrected for on-site Coulomb interactions (DFT+U) have been performed to study the supported rare earth catalysts with small Au nanoclusters (Au trimer, Au3) adsorbed at CeO2 surfaces. The interaction of Au3 with all the three major facets of crystalline CeO2, namely CeO(111), (110) and (1100), were systematically investigated. The results showed that Au3 can adsorbed rather strongly at the surfaces (Eads>3 eV), and partially reduce the CeO2 support by filling the originally empty 4forbital of one surface Ce with an electron. Moreover, corresponding to different configurations of surface relaxation caused by Au3 adsorption, the localized 4felectron can occur at different surface Ce near the Au3 at each surface. By calculating adsorption of O2, we also showed that only the surface Ce at Au3/Ce02(110) are capable of strongly holding and activating the O2.We also studied the 2×1 reconstructed CeO2(110) surface and the adsorption of bigger Aun clusters (n=3-8). Moreover, CO oxidation by O2 was calculated at Aug/CeO2(110) and the results showed the system with supported Au nanocluters at CeO2(110) is indeed efficient for O2 activation and reaction.