부산대학교 도서관

Leached Pt-Fe and Pt-Co catalysts were prepared by acid leaching the reduced catalysts in acid solution. Oxidation treatments of leached catalysts produced the structure of metal oxides decorating the surface of nanoparticles. The fully oxidized Fe2O3and Co3O4species on Pt nanoparticle surfaces result in the low performance of the CO complete oxidation (COOX) reaction. In contrast, unsaturated FeO and CoO surface species can be formed during exposure to the CO preferential oxidation (CO-PROX) reaction with an excess of H2, leading to a high O2activation ability and enhancing the CO-PROX activity. The FeOxsurface structures can be transformed between these two states by varying the reactive gas environments, exhibiting oscillating activity in these two reactions. Conversely, the CoO surface structure formed in the H2-rich atmosphere is stable when exposed to the COOX reaction and exhibits similar activity in these two reactions. It is hoped that this work may assist in understanding the important role of surface oxides in real reactions.