The dynamic behaviour of CH3OH and NO2 adsorbed on CeO2(111) studied by noncontact atomic force microscopy
The dynamic behaviour of CH3OH and NO2 adsorbed on CeO2(111) studied by noncontact atomic force microscopy
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DOI：
10.1088/0957-4484/15/2/011
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发表时间：
2004-01
期刊：
影响因子：
3.5
通讯作者：
Y. Namai;K. Fukui;Y. Iwasawa
中科院分区：
文献类型：
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作者：
Y. Namai;K. Fukui;Y. Iwasawa
采用非接触原子力显微镜(NC-AFM)研究了不同氧化态的CeO2(111)表面上甲醇(CH3OH)和二氧化氮(NO2)的吸附和反应。 CH3OH 暴露后，表面氧缺陷没有重建周围的氧原子，被甲氧基 (CH3O) 修复。在 CH3OH 气氛下，通过连续的 NC-AFM 观察，观察到表面氧原子与 CH3OH 的反应性的异质特征：由于化学事件而产生新的氧线缺陷。连续的 NC-AFM 测量还表明，稍微还原的 CeO2(111) 表面上的氧空位可以通过暴露于 NO2 来修复。 NC-AFM 图像中修复后的氧缺陷的对比度与其他表面氧原子的对比度相似。这表明缺陷处发生了NO2 的解离吸附。暴露于 NO2 后，在稍微还原的 CeO2(111) 表面上也观察到三氧化氮 (NO3)。在没有表面氧缺陷的CeO2(111)表面上，既没有观察到NO2的吸附，也没有观察到NO3的形成。简要讨论了线缺陷和NO3形成的反应机制。
The adsorption and reaction of methanol (CH3OH) and nitrogen dioxide (NO2) on CeO2(111) surfaces in different oxidation states were studied by noncontact atomic force microscopy (NC-AFM). After CH3OH exposure, surface oxygen defects without reconstruction of the surrounding oxygen atoms were healed by methoxy species (CH3O). Under a CH3OH atmosphere, a heterogeneous feature in the reactivity of surface oxygen atoms to CH3OH was observed by successive NC-AFM observation: new line defects of oxygen were produced as a result of a chemical event. Successive NC-AFM measurements also revealed that oxygen vacancies on a slightly reduced CeO2(111) surface were healed by exposure to NO2. The contrast of healed oxygen defects in NC-AFM images was similar to that of other surface oxygen atoms. This indicates that dissociative adsorption of NO2 occurred at the defects. Nitrogen trioxide (NO3) was also observed on a slightly reduced CeO2(111) surface after NO2 exposure. On a CeO2(111) surface without surface oxygen defects, neither adsorption of NO2 nor formation of NO3 was observed. The reaction mechanisms for the formation of line defects and NO3 are discussed briefly.