Atomic Structure and Dynamics of Single Platinum Atom Interactions with Monolayer MoS2
Atomic Structure and Dynamics of Single Platinum Atom Interactions with Monolayer MoS2
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DOI：
10.1021/acsnano.7b00796
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发表时间：
2017-03-01
期刊：
影响因子：
17.1
通讯作者：
Warner, Jamie H.
中科院分区：
文献类型：
--
作者：
Li, Huashan;Wang, Shanshan;Warner, Jamie H.
在60KV加速电压下，用像差校正的环状暗场扫描电子显微镜研究了单层MoS_2与单个铂原子之间的原子级相互作用。在原子分辨的单层MoS_2晶格上，单个铂原子的强烈反差使它们相对于MoS_2晶格的确切位置得以确定，从而显示出稳定的结合位置。在无表面污染的MoS_2区域，铂原子集中在S空位，并在电子束提供的能量驱动下动态跳跃到附近的空位。然而，在被碳表面层污染的MoS_2区域，铂原子出现在相对于MoS_2晶格的不同位置，包括在Mo的顶部和离轴位置。这些变化是由于铂与周围的非晶态碳层成键，破坏了固有的铂-MoS_2相互作用，导致了更多的位置变化。密度泛函理论(DFT)计算表明，MoS_2表面的铂原子具有较小的迁移势垒，当与单或双硫空位结合时，铂原子是稳定的。用密度泛函理论方法研究了铂掺杂对MoS_2基面析氢反应催化活性的影响。这种强烈的催化效应对界面构型的依赖在一系列掺杂剂中是常见的，这可能提供一种创建和优化反应中心的手段。
We have studied atomic level interactions between single Pt atoms and the surface of monolayer MoS2 using aberration-corrected annular dark field scanning transmission electron microscopy at an accelerating voltage of 60 kV. Strong contrast from single Pt atoms on the atomically resolved monolayer MoS2 lattice enables their exact position to be determined with respect to the MoS2 lattice, revealing stable binding sites. In regions of MoS2 free from surface contamination, the Pt atoms are localized in S vacancy sites and exhibit dynamic hopping to nearby vacancy sites driven by the energy supplied by the electron beam. However, in areas of MoS2 contaminated with carbon surface layers, the Pt atoms appear at various positions with respect to the underlying MoS2 lattice, including on top of Mo and in off-axis positions. These variations are due to the Pt bonding with the surrounding amorphous carbon layer, which disrupts the intrinsic Pt MoS2 interactions, leading to more varied positions. Density functional theory (DFT) calculations reveal that Pt atoms on the surface of MoS2 have a small barrier for migration and are stabilized when bound to either a single or double sulfur vacancies. DFT calculations have been used to understand how the catalytic activity of the MoS2 basal plane for hydrogen evolution reaction is influenced by Pt dopants by variation of the hydrogen adsorption free energy. This strong dependence of catalytic effect on interfacial configurations is shown to be common for a series of dopants, which may provide a means to create and optimize reaction centers.