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Density Functional Theory Study of Nucleation and Growth of Pt Nanoparticles on MoS2(001) Surface

机译：MoS2（001）表面Pt纳米颗粒成核与生长的密度泛函理论研究

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摘要

The dispersion of Pt metallic nanoparticles on different supports is of high relevance for designing more efficient and less expensive catalysts. In order to understand the nucleation and epitaxial growth of Pt nanoparticles and thin films on MoS2 monolayers, we have systematically analyzed, by first-principles density functional calculations, the evolution of morphology and atomic structure of supported (Pt)(n) nanoparticles (NPs) on MoS2(001) for n <= 12. We find that n = 5 is the cluster size where the growth of the NPs transforms from two- to three-dimensional (2D to 3D). Owing to the topography of MoS2(001), the 2D NPs mostly attach to the support via direct bonding with Mo atoms that sit in the troughs of the surface, while the 3D NPs are bonded to the sulfur atoms that are more extended in the vacuum region. Furthermore, we find that Pt is sufficiently mobile on the surface where the number of hopping events per second is approximate to 10(3) s(-1) along [10 (1) over bar] and approximate to 10 s(-1) along [1 (1) over bar0] at room temperature. The somewhat large mobility suggests that monomer diffusion is not likely to be the rate-limiting step for Oswald ripening and that Pt sputtering on MoS2(001) will result in relatively large particles rather than a fine dispersion. The existence of a fast diffusion channel along [10 (1) over bar] suggests that the morphology of the NPs is anisotropic.
机译：Pt金属纳米颗粒在不同载体上的分散性与设计更高效，更便宜的催化剂具有高度相关性。为了了解MoS2单层上Pt纳米颗粒和薄膜的形核和外延生长，我们通过第一原理密度泛函计算系统地分析了负载（Pt）（n）纳米颗粒（NPs）的形貌和原子结构的演变）在MoS2（001）上的n <=12。我们发现n = 5是簇的大小，其中NP的增长从二维转换为三维（从2D到3D）。由于MoS2（001）的形貌，2D NP主要通过与位于表面槽中的Mo原子直接键合而附着在载体上，而3D NPs则与真空中更易延伸的硫原子键合地区。此外，我们发现Pt在表面上具有足够的移动性，每秒的跳跃事件数沿[bar上的10（1）]大约为10（3）s（-1），并且大约为10 s（-1）在室温下沿着[1（1）在bar0上）移动。稍大的迁移率表明，单体扩散不太可能成为奥斯瓦尔德熟化的限速步骤，并且在MoS2（001）上进行Pt溅射将产生相对较大的颗粒，而不是细小的分散体。沿[10（1）over bar]的快速扩散通道的存在表明，NP的形态是各向异性的。

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