Growth and Electronic Properties of Ag Nanoparticles on Reduced CeO2-x(111) Films

Ag nanoparticles grown on reduced CeO2 thin films have been studied by X-ray photoelectron spectroscopy and resonant photoelectron spectroscopy of the valence band to understand the effect of oxygen vacancies in the CeO2-x thin films on the growth and interfacial electronic properties of Ag. Ag grows as three-dimensional particles on the CeO2-x (111) surface at 300 K. Compared to the fully oxidized ceria substrate surface, Ag favors the growth of smaller particles with a larger particle density on the reduced ceria substrate surface, which can be attributed to the nucleation of Ag on oxygen vacancies. The binding energy of Ag3d increases when the Ag particle size decreases, which is mainly attributed to the final-state screening. The interfacial interaction between Ag and CeO2(111) is weak. The resonant enhancement of th.e 4f level of Ce3+ species in RPES indicates a partial Ce4+ Ce3+ reduction after Ag deposited on reduced ceria surface. The sintering temperature of Ag on CeO1.85 (111) surface during annealing is a little higher than that of Ag on CeO2 (111) surface, indicating that Ag nanoparticles are more stable on the reduced ceria surface.