摘要
采用密度泛函理论研究了CO气氛对FeO(111)/Ru(0001)负载Au原子吸附位、电荷及其稳定性的影响.首先考察了FeO(111)单层薄膜在Ru(0001)表面上的界面结构.研究发现,表面莫尔超晶胞内的HCP区域有最小的Fe-O层间距(rumpling),且Fe和O原子均与衬底Ru形成化学键.Au原子在FeO/Ru(0001)上最稳定的吸附在HCP区域的Fe-bridge位.其中,Au原子诱导两个Fe原子从O原子层的下面翻转到其上面,形成两个Au–Fe键,且Au带负电.当把体系暴露在CO气氛下后,CO能诱导Au原子从原来最稳定的Fe-bridge位转移到其邻近的O-top位,伴随着Au的电荷从负变到正,形成非常稳定的Au+–CO羰基物.结果表明,反应气氛对负载金属催化剂的化学状态及其稳定性的影响很大;同时也强调了反应条件下催化剂原位表征的重要性.
A first principles study of the influence of CO adsorption on the charge state,adsorption site,and stability of Au adatoms on FeO/Ru(0001) was presented.Calculations were first carried out to explore the detailed interface structure of a bilayer FeO(111) film on Ru(0001).The HCP domain inside the Moire supercell has a rather small rumpling with both the Fe and O atoms directly bonded to the Ru substrate.The most stable adsorption of an Au atom on FeO/Ru(0001) is at the Fe-bridge site in the HCP domain,where Au binds with two flipped Fe atoms and is negatively charged.After exposure to CO,the Au anions at the Fe-bridge site changed their position to the O-top site by overcoming a small barrier of only 0.12 eV,where they formed stable Au+-CO species with a significant reduction in the formation energy.The results highlighted the importance of in situ characterization of supported catalysts under reaction conditions,and implications on catalyst stability were also discussed.
出处
《催化学报》
CSCD
北大核心
2013年第10期1820-1825,共6页
基金
the National Natural Science Foundation of China(21173210,21225315)
the National Basic Research Program of China(973 Program,2013CB834603)~~
关键词
密度泛函理论
一氧化碳
金
氧化铁薄膜
Density functional theory
Carbon monoxide
Gold
Iron oxide film
