The bulk properties and surface chemical reactivity of compositionally disordered Pt–Fe and Pt–Co alloys in the fcc A1 phase have been investigated theoretically in comparison to the ordered alloys of the same compositions. The results are analyzed together with our previously reported findings for Pt–Ni. Nonlinear variation is observed in lattice constant, d band center, magnetic moment, and hydrogen adsorption energy across the composition range (0–100 atomic % of Pt, x_Pt). The Pt 5d states are strongly perturbed by the 3d states of the base metals, leading to notable density of states above the Fermi level and residual magnetic moments at high x_Pt. Surface reactivity in terms of average H adsorption energy varies continuously with composition between the monometallic Fe–Pt and Co–Pt limits, going through a maximum around x_Pt = 0.5–0.75. Close inspection reveals a significant variation in site reactivity at x_Pt < 0.75, particularly with disordered Pt–Fe alloys due in part to the inherent disparity in chemical reactivity between Fe and Pt. Furthermore, the strong interaction between Fe and Pt causes Pt-rich sites to be less reactive toward H than Pt-rich sites on disordered Pt–Ni alloy surfaces, despite less compressive strain caused. These results provide theoretical underpinnings for conceptualizing and understanding the performance of these Pt-base metal alloys in key catalytic applications and for efforts to tailor Pt-alloys as catalysts.

中文翻译：

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有序和无序 Pt-Fe 和 Pt-Co 合金上的氢吸附


与相同成分的有序合金相比，从理论上研究了 fcc A1 相中成分无序的 Pt-Fe 和 Pt-Co 合金的整体性能和表面化学反应性。结果与我们之前报道的 Pt-Ni 研究结果一起进行分析。在整个成分范围（Pt 的 0–100 原子%，x _Pt ）内，观察到晶格常数、d 带中心、磁矩和氢吸附能的非线性变化。 Pt 5d 态受到贱金属 3d 态的强烈扰动，导致高于费米能级的显着态密度和高 x _Pt 处的残余磁矩。就平均 H 吸附能而言，表面反应性随着单金属 Fe-Pt 和 Co-Pt 极限之间的成分不断变化，在 x _Pt = 0.5–0.75 左右达到最大值。仔细检查发现，x _Pt < 0.75 处的位点反应性存在显着变化，特别是对于无序 Pt-Fe 合金，部分原因是 Fe 和 Pt 之间化学反应性的固有差异。此外，Fe和Pt之间的强相互作用导致富Pt位点对H的反应性比无序Pt-Ni合金表面上的富Pt位点低，尽管引起的压缩应变较小。这些结果为概念化和理解这些 Pt 基金属合金在关键催化应用中的性能以及定制 Pt 合金作为催化剂的努力提供了理论基础。