The mechanism of carbon monoxide oxidation over gold was explored using a model planar catalyst consisting of monodisperse gold nanoparticles periodically arranged on single crystal SiO₂/Si(111) substrates using a combination of Grazing Incidence Small Angle X-ray Scattering and Grazing Incidence X-ray Diffraction (GISAXS/GIXD) under reaction conditions. It is shown that nanoparticle composition, size and shape change when the catalyst is exposed to reactive gases. During CO oxidation, the particle’s submergence depth with respect to the surface decreases due to the removal of gold oxide at the metal-support edge, meanwhile the particle ‘flattens’ to maximise the number of the reaction sites along its perimeter. The effect of the CO concentration on the catalyst structure is also discussed. Our results support the dual catalytic sites mechanism whereby CO is activated on the gold surface whereas molecular oxygen is dissociating at the gold–support interface.

中文翻译：

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通过操作掠入射X射线散射分析揭示了负载型金纳米颗粒上的CO氧化

使用模型平面催化剂探索了一氧化碳在金上的氧化机理，该催化剂由周期性分布在单晶SiO ₂上的单分散金纳米颗粒组成/ Si（111）基板在反应条件下结合使用掠入射小角度X射线散射和掠入射X射线衍射（GISAXS / GIXD）。结果表明，当催化剂暴露于反应性气体中时，纳米颗粒的组成，尺寸和形状都会发生变化。在CO氧化过程中，由于去除了金属载体边缘的氧化金，使颗粒相对于表面的浸入深度减小，同时颗粒“展平”以使沿其周边的反应位点数量最大化。还讨论了CO浓度对催化剂结构的影响。我们的结果支持双重催化位点机制，其中CO在金表面上被激活，而分子氧在金-载体界面处解离。