(560fg) The Role of Noble Metals (M=Rh,Pd,Ag,Au,Pt) Promoting Active Oxygen Enhancing Soot Oxidation in CeO2 Vacancy : Experiment with Tight Contact and a DFT Study

A series of CeO2-based catalysts were investigated for soot oxidation with O2. The initial activity of the catalyst is determined by the number of catalyst–soot contact points rather than the catalytic surface, while the catalyst stability is closely related to the concentration of surface oxygen vacancies. Especially, many of literatures are dealing oxygen vacancy with active oxygen such as superoxide (O2-) and peroxide (O2-) species. When the CeO2 surface is partially reduced, a surface oxygen vacancy forms, and two Ce4+ ions of substrate are reduced to Ce3+ones. However, the original reasons for ‘how the active oxygens are generated’ is not clearly revealed yet. In this study, we suggest the main cause determining superoxide and peroxide in surface oxygen by comparing the ground state energy with DFT calculation. Moreover, we found outstanding catalytic performance in Rh/CeO2 catalyst with tight contact thus, we suggest the linear tendency between calculated binding energy of active oxygen with soot oxidation rate experimentally measured. Also, we performed surface bader charge transfer to observe the role of metal as electron supplier at catalytic surface.