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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.
The effect of CO on the adsorption site, charge and stability of Au atom on FeO (111) / Ru (0001) was investigated by using density functional theory. Firstly, the effect of CO on the Ru (0001) surface of FeO The results showed that the HCP region in the superlattice had the smallest Fe-O layer spacing, and both Fe and O atoms formed a chemical bond with the substrate Ru.Au atoms in FeO / Ru (0001 ) On the most stable adsorption in the HCP region of the Fe-bridge bit where the Au atom induces two Fe atoms from the O atomic layer turned over to the top to form two Au-Fe bonds, and Au negatively charged when the After the system is exposed to CO atmosphere, CO can induce the transfer of Au atoms from the most stable Fe-bridge to its adjacent O-top. With the charge of Au changing from negative to positive, CO forms a very stable Au + -CO The results showed that the reaction atmosphere had a great influence on the chemical state and stability of the supported metal catalyst. The importance of the in situ characterization of the catalyst under the reaction conditions was also emphasized.