Binary clusters AuPt and Au6Pt: structure and reactivity within density functional theory.
Binary clusters AuPt and Au6Pt: structure and reactivity within density functional theory.
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DOI：
10.1021/jp055506o
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发表时间：
2006-04
期刊：
影响因子：
--
通讯作者：
W. Tian;Maofa Ge;F. Gu;Toshiki Yamada;Y. Aoki
中科院分区：
文献类型：
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作者：
W. Tian;Maofa Ge;F. Gu;Toshiki Yamada;Y. Aoki
在密度泛函理论中，采用广义梯度近似方法研究了AuPt和Au（6）Pt团簇的结构和反应活性. AuPt的键强度介于Au（2）和Pt（2）之间，更接近于Au（2）。根据电子结构分析，Pt原子是AuPt和AuPt（+）中的反应中心。AuPt（+）比AuPt更稳定。Au（6）Pt更倾向于具有低多重性的电子态。Au（6）Pt的最稳定构象是单线态，具有准平面六角结构，Pt位于六角中心。Pt在Au团簇中的掺杂增强了Au团簇的化学区域选择性。在Au（6）Pt中，Pt原子基本上充当电子供体，而键合到Pt原子上的Au原子充当电子受体。最低的三重态的边缘覆盖的菱形Au（6）Pt团簇是容易接近的非常小的单重态-三重态能隙（0.32 eV）。O（2）优先吸附在Au上，CO优先吸附在Pt上。O（2）和CO在AuPt上的吸附比在Au（6）Pt上的吸附强。CO在AuPt簇上的吸附比O（2）强得多。CO在Pt上的吸附改变了AuPt团簇的几何结构。
Within density functional theory with the general gradient approximation for the exchange and correlation, the bimetallic clusters AuPt and Au(6)Pt have been studied for their structure and reactivity. The bond strength of AuPt lies between those of Au(2) and Pt(2), and it is closer to that of Au(2). The Pt atom is the reactive center in both AuPt and AuPt(+) according to electronic structure analysis. AuPt(+) is more stable than AuPt. Au(6)Pt prefers electronic states with low multiplicity. The most stable conformation of Au(6)Pt is a singlet and has quasi-planar hexagonal frame with Pt lying at the hexagonal center. The doping of Pt in Au cluster enhances the chemical regioselectivity of the Au cluster. The Pt atom essentially serves as electron donor and the Au atoms bonded to the Pt atom acts as electron acceptor in Au(6)Pt. The lowest triplet of edge-capped rhombus Au(6)Pt clusters is readily accessible with very small singlet-triplet energy gap (0.32 eV). O(2) prefers to adsorb on Au and CO prefers to adsorb on Pt. O(2) and CO have stronger adsorption on AuPt than they do on Au(6)Pt. CO has a much stronger adsorption on AuPt bimetallic cluster than O(2) does. The adsorption of CO on Pt modifies the geometry of AuPt bimetallic clusters.