论文标题
粒度效果对超然氧化铝膜支撑的常规PD簇的langmuir-hinshelwood屏障的氧化作用
Particle size effect on the Langmuir-Hinshelwood barrier for CO oxidation on regular arrays of Pd clusters supported on ultrathin alumina films
论文作者
论文摘要
Langmuir-Hinshelwood屏障（ELH）和用于CO氧化的指数因子（$ν$ LH）已在高温下在Ni3al上支撑的PD簇的六角形阵列上测量（111）。 PD簇的尺寸分布急剧，平均尺寸为：174 $ \ pm $ 13、360 $ \ pm 19 $ 19和768 $ \ pm $ \ $ 28 ATOMS。 ELH和$ν$ LH是由在PD簇上具有吸附氧饱和层的CO分子束的初始反应速率确定的，该反应层在不同的温度下测量（493 $ \ le $ t（k）$ \ le $ 613）。最大的颗粒（3.5 nm）给出了ELH的值和$ν$ LH的值，类似于在PD（111）[2]上测得的值。但是，较小的颗粒（2.7和2.1 nm）显示出非常不同的行为。这种尺寸效应的起源是根据电子结构的变化和PD簇的原子结构的变化来讨论的。
The Langmuir-Hinshelwood barrier (ELH) and the pre-exponential factor ($ν$LH) for CO oxidation have been measured at high temperature on hexagonal arrays of Pd clusters supported on an ultrathin alumina film on Ni3Al(111). The Pd clusters have a sharp size distribution and the mean sizes are: 174$\pm$13, 360$\pm$19 and 768$\pm$28 atoms. ELH and $ν$LH are determined from the initial reaction rate of a CO molecular beam with a saturation layer of adsorbed oxygen on the Pd clusters, measured at different temperatures (493$\le$T (K) $\le$613). The largest particles (3.5 nm) give values of ELH and $ν$LH similar to those measured on Pd (111) [2]. However, smaller particles (2.7 and 2.1 nm) show very different behavior. The origin of this size effect is discussed in terms of variation of the electronic structure and of the atomic structure of the Pd clusters.
