AVS 62nd International Symposium & Exhibition
    Surface Science Wednesday Sessions
       Session SS+AS+EN-WeA

Paper SS+AS+EN-WeA4
Density Functional Study of the Oxygen Chemistry and NO Oxidation Mechanism on Low-index Surfaces of SmMn2O5 mullite

Wednesday, October 21, 2015, 3:20 pm, Room 113

Session: Metals, Alloys & Oxides: Reactivity and Catalysis
Presenter: Bin Shan, Huazhong University of Science and Technology, China
Authors: X. Liu, Huazhong University of Science and Technology, China
Z.Z. Chen, Huazhong University of Science and Technology, China
K.J. Cho, The University of Texas at Dallas
R. Chen, Huazhong University of Science and Technology, China
B. Shan, Huazhong University of Science and Technology, China
Correspondent: Click to Email
SmMn2O5 mullite has recently been reported to be a promising alternative to traditional Pt-based catalysts for environmental and energy applications. By performing density functional calculations, we systematically investigated lattice oxygen reactivity and oxygen adsorption/dissociation/migration behaviors on low index surfaces of SmMn2O5 mullite with different terminations. The (001), (010) and (100)surfaces have lowest barriers against exchanging O species with environments and thus are expected to be active surfaces.Furthermore, we have calculated the reaction routes along different channels on these three surfaces. Our results show that both ER and MvK mechanisms co-exist in NO oxidation by SmMn2O5. The most active surface is the (010) facet with Mn4+ ions in the surface layer where oxidation can be realized by a synergetic mechanism involving ER processes along bridge-MnO channels. The (001) surface with Mn4+ ions in the surface layer is also expected to be active for oxidation via the MvK mechanism. On the other hand, despite the low oxygen vacancy formation energy, the (110) surface could easily undergo surface reconstruction and quickly lose active sites. Our calculations also suggest that the rate determining step of oxidation reaction on SmMn2O5 surfaces is the desorption of NO2 on both (010) and (001) facets. Our study presents systematic pictures on catalytic activities of SmMn2O5, which are important to the full understanding and improvement of SmMn2O5 performance. The comprehensive micro-kinetic model on the reaction dynamics of SmMn2O5 is under construction.