The origin of the synergistic catalytic effect between metal catalysts and reducible oxides has been debated for decades. Clarification of this effect, namely, the strong metal-support interaction (SMSI), requires an understanding of the geometric and electronic structures of metal-metal oxide interfaces under operando conditions. We show that the inherent lattice mismatch of bimetallic materials selectively creates surface segregation of subsurface metal atoms. Interfacial metal-metal oxide nanostructures are then formed under chemical reaction environments at ambient pressure, which thus increases the catalytic activity for the CO oxidation reaction. Our in situ surface characterizations using ambient-pressure scanning tunneling microscopy and ambient-pressure x-ray photoelectron spectroscopy exhibit (i) a Pt-skin layer on the Pt-Ni alloyed surface under ultrahigh vacuum, (ii) selective Ni segregation followed by the formation of NiO_1-x clusters under oxygen gas, and (iii) the coexistence of NiO_1-x clusters on the Pt-skin during the CO oxidation reaction. The formation of interfacial Pt-NiO_1-x nanostructures is responsible for a highly efficient step in the CO oxidation reaction. Density functional theory calculations of the Pt₃Ni(111) surface demonstrate that a CO molecule adsorbed on an exposed Pt atom with an interfacial oxygen from a segregated NiO_1-x cluster has a low surface energy barrier of 0.37 eV, compared with 0.86 eV for the Pt(111) surface.

中文翻译：

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在Pt3Ni（111）合金表面上形成吸附剂驱动的反应性界面Pt-NiO1-x纳米结构。

数十年来，人们一直在争论金属催化剂和可还原氧化物之间协同催化作用的起源。要澄清这种效应，即强金属-载体相互作用（SMSI），需要了解操作条件下金属-金属氧化物界面的几何和电子结构。我们表明，双金属材料固有的晶格失配选择性地产生了地下金属原子的表面偏析。然后在环境压力下在化学反应环境下形成界面金属-金属氧化物纳米结构，因此增加了CO氧化反应的催化活性。在氧气下_{1- x}团簇，以及（iii）在CO氧化反应过程中NiO _{1- x}团簇在Pt皮肤上共存。界面Pt-NiO ₁ - _x纳米结构的形成负责CO氧化反应中的高效步骤。Pt ₃ Ni（111）表面的密度泛函理论计算表明，从偏析的NiO _{1- x}团簇中吸附有界面氧和暴露的Pt原子的CO分子具有0.37 eV的低表面能垒，而0.86 eV用于Pt（111）表面。