The relative stabilities of different chemical arrangements of Pd–Ir and Au–Rh nanoalloys (and their pure metal equivalents) are studied, for a range of compositions, for fcc truncated octahedral 38- and 79-atom nanoparticles (NPs). For the 38-atom NPs, comparisons are made of pure and alloy NPs supported on a TiO₂(110) slab. The relative energies of different chemical arrangements are found to be similar for Pd–Ir and Au–Rh nanoalloys, and depend on the cohesive and surface energies of the component metals. For supported nanoalloys on TiO₂, the interaction with the surface is greater for Ir (Rh) than Pd (Au): most of the pure NPs and nanoalloys preferentially bind to the TiO₂ surface in an edge-on configuration. When Au–Rh nanoalloys are bound to the surface through Au, the surface binding strength is lower than for the pure Au NP, while the Pd-surface interaction is found to be greater for Pd–Ir nanoalloys than for the pure Pd NP. However, alloying leads to very little difference in Ir-surface and Rh-surface binding strength. Comparing the relative stabilities of the TiO₂-supported NPs, the results for Pd–Ir and Au–Rh nanoalloys are the same: supported Janus NPs, whose Ir (Rh) atoms bind to the TiO₂ surface, bind most strongly to the surface, becoming closer in energy to the core–shell configurations (Ir@Pd and Rh@Au) which are favoured for the free particles.

中文翻译：

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模拟游离态和氧化物负载型纳米合金催化剂：本体不混溶的Pd-Ir和Au-Rh体系的比较以及TiO ₂载体的影响

对于fcc截短的八面体38和79原子纳米颗粒（NP），研究了Pd-Ir和Au-Rh纳米合金（及其纯金属等价物）不同化学排列的相对稳定性。对于38个原子的NP，比较了负载在TiO ₂（110）平板上的纯NP和合金NP 。对于Pd-Ir和Au-Rh纳米合金，发现不同化学排列的相对能量相似，并且取决于组分金属的内聚能和表面能。对于TiO ₂上负载的纳米合金，Ir（Rh）的表面相互作用大于Pd（Au）：大多数纯NP和纳米合金优先结合TiO ₂表面呈边缘配置。当Au–Rh纳米合金通过Au与表面结合时，其表面结合强度低于纯Au NP，而Pd–Ir纳米合金的Pd-表面相互作用要大于纯Pd NP。但是，合金化导致Ir表面和Rh表面结合强度的差异很小。比较TiO ₂负载的NPs的相对稳定性，Pd–Ir和Au–Rh纳米合金的结果相同：负载的Janus NP，其Ir（Rh）原子与TiO ₂表面结合，与表面的结合最牢固，使能量变得更接近于核-壳结构（Ir @ Pd和Rh @ Au），这是自由粒子的首选。