CeO2 Thickness-Dependent SERS and Catalytic Properties of CeO2-on-Ag Particles Synthesized by O2-Assisted Hydrothermal Method

Oxide-on-metal particles with exposed interfaces exhibit wealthy structures and functions, but their facile synthesis remains as a challenge. Herein we report a facile O2-assisted hydrothermal method to synthesize CeO2-on-Ag particles with different CeO2 thicknesses. In this novel approach Ag particles catalyze the O2 + H2O reaction to form surface hydroxyls that induce the preferential nucleation of Ce(OH)3 on the surfaces of Ag particles, eventually forming CeO2 adlayers on Ag particles. CeO2-on-Ag particles exhibit the CeO2 thickness-dependent SERS effect in which their best SERS effect is 2 orders stronger than that of Ag particles. They also exhibit CeO2 thickness-dependent catalytic performance in CO oxidation in which the best one is as active as traditional CeO2-supported Ag catalyst. These results open up new opportunities to synthesize oxide-on-metal particles and explore their functions by tuning the oxide adlayer thickness.