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Cu-CeO2体系因其特殊的催化能力而在固体氧化物燃料电池和水煤气转化反应等多个催化领域有重要应用.采用基于密度泛函理论的第一性原理方法,在原子和电子层面上系统地研究了单个Cu原子及Cu小团簇在CeO2(110)面上的吸附构型,价键特性和电子结构,结果表明:1)单个Cu原子的最稳定吸附位是两个表面O的桥位;2)Cu团簇的稳定吸附构型为扭曲的四面体结构;3)Cu原子及Cu团簇的吸附在CeO2(110)面的gap区域引入了间隙态,这些间隙态主要来自于Cu及其近邻的O和表层还原形成的Ce3+,间隙态的出现表明Cu的吸附增强了CeO2(110)表面的活性;4)吸附的单个Cu原子及Cu团簇分别被CeO2(110)面表层的Ce4+离子氧化形成了Cuδ+和Cuδ+4,并伴随着Ce3+离子的形成,这个反应可归结为Cux/Ce4+→Cuδ+x/Ce3+;5)Cu团簇的吸附比Cu单原子的吸附引入了更多的Ce3+离子,进而形成了更多的Cuδ+-Ce3+催化活性中心.结合已报道的Cu/CeO2(111)界面特性,更加全面地探明了Cu与CeO2(111)和(110)两个较稳定低指数表面的协同作用特性,较为系统地揭示了Cu增强CeO2催化特性的原因及Cu与CeO2协同作用的内在机理.
Due to its special catalytic ability, Cu-CeO2 system has important applications in many catalytic fields such as solid oxide fuel cell and water gas conversion reaction.Using the first-principle method based on density functional theory, the system The results show that: 1) The most stable adsorption sites of a single Cu atom are the bridges of two surface O’s 2) the stable adsorption configuration of Cu clusters is distorted tetrahedron structure; 3) the adsorption of Cu atoms and Cu clusters introduces interstitial states in the gap region of CeO2 (110) plane, and these interstitials mainly come from Cu The presence of interstitial states suggests that the adsorption of Cu enhances the activity of CeO2 (110) surface. 4) The adsorption of single Cu atoms and Cu clusters by CeO2 (110) surface layer Ce4 + ions form Cuδ + and Cuδ + 4 with the formation of Ce3 + ions. This reaction can be attributed to Cux / Ce4 + → Cuδ + x / Ce3 +. 5) More Ce3 + ions, which in turn form more Cuδ + -Ce3 + catalytic centers. The Cu / CeO2 (111) interfacial properties of the Cu / CeO2 (111) interface are more comprehensively demonstrated by the synergistic interaction between Cu and the more stable low index surfaces of CeO2 (111) and (110) Reasons and the Internal Mechanism of Cu and CeO2 Synergism.