Mamatkulov Mikhail, Yudanov Ilya V, Bukhtiyarov Andrey V, Neyman Konstantin M
Boreskov Institute of Catalysis of the Siberian Branch of the Russian Academy of Sciences (BIC SB RAS), Novosibirsk 630090, Russia.
Departament de Ciència de Materials i Química Física and Institut de Quimica Teòrica i Computacional, Universitat de Barcelona, c/Martí i Franquès 1, 08028 Barcelona, Spain.
Nanomaterials (Basel). 2021 Jan 7;11(1):122. doi: 10.3390/nano11010122.
Structure of model bimetallic PdAu nanoparticles is analyzed aiming to find Pd:Au ratios optimal for existence of Pd1 single-atom surface sites inside outer Au atomic shell. The analysis is performed using density-functional theory (DFT) calculations and topological approach based on DFT-parameterized topological energy expression. The number of the surface Pd1 sites in the absence of adsorbates is calculated as a function of Pd concentration inside the particles. At low Pd contents none of the Pd atoms emerge on the surface in the lowest-energy chemical orderings. However, surface Pd1 sites become stable, when Pd content inside a Pd-Au particle reaches ca. 60%. Further Pd content increase up to almost pure Pd core is accompanied by increased concentration of surface Pd atoms, mostly as Pd1 sites, although larger Pd ensembles as dimers and linear trimers are formed as well. Analysis of the chemical orderings inside PdAu nanoparticles at different Pd contents revealed that enrichment of the subsurface shell by Pd with predominant occupation of its edge positions precedes emergence of Pd surface species.
对模型双金属钯金纳米颗粒的结构进行了分析，旨在找到在外层金原子壳内存在单原子表面位点Pd1的最佳钯金比例。该分析使用密度泛函理论（DFT）计算和基于DFT参数化拓扑能量表达式的拓扑方法进行。在不存在吸附质的情况下，表面Pd1位点的数量作为颗粒内钯浓度的函数进行计算。在低钯含量时，在最低能量化学排序中，没有钯原子出现在表面上。然而，当钯金颗粒内的钯含量达到约60%时，表面Pd1位点变得稳定。进一步将钯含量增加到几乎纯钯核时，表面钯原子的浓度增加，主要以Pd1位点的形式存在，但也会形成更大的钯聚集体，如二聚体和线性三聚体。对不同钯含量下钯金纳米颗粒内部化学排序的分析表明，在钯表面物种出现之前，次表面壳层会被钯富集，且其边缘位置被优先占据。
