Effect of graphene support on large Pt nanoparticles.
Effect of graphene support on large Pt nanoparticles.
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DOI：
10.1039/c6cp07334d
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发表时间：
2016-12
期刊：
影响因子：
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通讯作者：
L. G. Verga;Jolyon Aarons;M. Sarwar;D. Thompsett;A. Russell;Chris-Kriton Skylaris
中科院分区：
文献类型：
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作者：
L. G. Verga;Jolyon Aarons;M. Sarwar;D. Thompsett;A. Russell;Chris-Kriton Skylaris
现有技术的催化剂通常通过在载体上沉积催化材料的单层、亚单层或纳米颗粒来产生，目的是增加表面积并降低催化材料的负载量，从而降低总成本。在这里，我们采用大规模DFT计算来模拟铂簇与多达309个原子与单层石墨烯支持多达880个碳原子的相互作用。我们计算的吸附，凝聚力和形成能量的二维和三维的Pt团簇与支持，包括通过半经验色散校正和vdW功能的色散相互作用。我们发现三维Pt团簇在与支撑物相互作用时比二维Pt团簇更稳定，并且它们的稳定性差异随着系统尺寸的增大而增大。此外，分散体的相互作用是更明显的，因为我们增加了纳米粒子的大小，是必不可少的一个可靠的描述更大的系统。我们观察到原子间的膨胀（收缩）的最接近（最远）的铂方面从石墨烯片和电荷重新分配与总的电荷被转移到支持的铂簇。与系统中的电荷转移相关的Pt-Pt膨胀与石墨烯接触的每个Pt原子的吸附能相关。这些，以及其他电子和结构的观察表明，支持的效果不能忽视。我们的研究提供了第一次，据我们所知，定量结果的非平凡的组合的大小和支持的纳米粒子的大小，这是相关的催化剂设计的影响。
State-of-the-art catalysts are often created via deposition of monolayers, sub-monolayers or nanoparticles of the catalytic material over supports, aiming to increase the surface area and decrease the loading of the catalytic material and therefore the overall cost. Here, we employ large-scale DFT calculations to simulate platinum clusters with up to 309 atoms interacting with single layer graphene supports with up to 880 carbon atoms. We compute the adsorption, cohesion and formation energies of two and three-dimensional Pt clusters interacting with the support, including dispersion interactions via a semi-empirical dispersion correction and a vdW functional. We find that three-dimensional Pt clusters are more stable than the two-dimensional when interacting with the support, and that the difference between their stabilities increases with the system size. Also, the dispersion interactions are more pronounced as we increase the nanoparticle size, being essential to a reliable description of larger systems. We observe inter-atomic expansion (contraction) on the closest (farthest) Pt facets from the graphene sheet and charge redistribution with overall charge being transferred from the platinum clusters to the support. The Pt-Pt expansion, which is related to the charge transfer in the system, correlates with the adsorption energy per Pt atom in contact with the graphene. These, and other electronic and structural observations show that the effect of the support cannot be neglected. Our study provides for the first time, to the best of our knowledge, quantitative results on the non-trivial combination of size and support effects for nanoparticles sizes which are relevant to catalyst design.