分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间: 2017-05-02
摘要: A well-dispersed noble metal on perovskite support is expected to show good catalytic ability for NO oxi- dation under oxygen-rich conditions, which is an important step in reducing NO in lean burn exhaust gas. In this study, we investigated the catalytic oxidation of NO to NO2 on a Pt4/CaTiO3 (001) model to eval- uate interfacial effect. Results showed that O2 preferred Pt–Ti interface sites, and that the decomposition of O2 required a dissociation activation barrier of 0.97 eV. The decomposed O–O on the interface required nearly no activation barrier in the subsequent NO oxidation. However, the most rate-limiting step involved the desorption of the second formed NO2 from interfacial Pt4/CaTiO3 (0 0 1), which yielded a sig- nificant desorption barrier of 2.63 eV. These findings can help understand the oxidation process of NO to NO2 on noble-metal–perovskite interface.
分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间: 2017-05-02
摘要: In the present work, we investigated the structural and catalytic properties of a prototype system Pt-doped CaTiO3 by means of first principles calculations. We paid particular attention to the aggregation and penetration of Pt on different surfaces of CaTiO3, and subsequent CO oxidation by surface oxygen atoms on Pt-doped CaTiO3. Our calculations indicate that CO oxidation can potentially take place when Pt is doped on the first layer of CaTiO3(001). The activation barriers are calculated to be 0.20–0.45 eV. The possibly induced O vacancy on the surface will produce a magnetic behavior by breaking the spin density symmetry due to one Pt–O bond cleavage. Our study is expected to provide an insight into the catalytic behavior of Pt ions in Pt-doped perovskite toward the oxidation of exhaust gas.