Atomic-scale insights into how supported metal nanoparticles catalyze chemical reactions are critical for the optimization of chemical conversion processes. It is well-known that different geometric configurations of surface atoms on supported metal nanoparticles have different catalytic reactivity and that the adsorption of reactive species can cause reconstruction of metal surfaces. Thus, characterizing metallic surface structures under reaction conditions at atomic scale is critical for understanding reactivity. Elucidation of such insights on high surface area oxide supported metal nanoparticles has been limited by less than atomic resolution typically achieved by environmental transmission electron microscopy (TEM) when operated under realistic conditions and a lack of correlated experimental measurements providing quantitative information about the distribution of exposed surface atoms under relevant reaction conditions. We overcome these limitations by correlating density functional theory predictions of adsorbate-induced surface reconstruction visually with atom-resolved imaging by in situ TEM and quantitatively with sample-averaged measurements of surface atom configurations by in situ infrared spectroscopy all at identical saturation adsorbate coverage. This is demonstrated for platinum (Pt) nanoparticle surface reconstruction induced by CO adsorption at saturation coverage and elevated (>400 K) temperature, which is relevant for the CO oxidation reaction under cold-start conditions in the catalytic convertor. Through our correlated approach, it is observed that the truncated octahedron shape adopted by bare Pt nanoparticles undergoes a reversible, facet selective reconstruction due to saturation CO coverage, where {100} facets roughen into vicinal stepped high Miller index facets, while {111} facets remain intact.

中文翻译：

---

通过 DFT 计算结合原位 TEM 和 IR 在饱和覆盖下 CO 诱导的 Pt 纳米粒子表面重建的定量和原子尺度视图

对负载金属纳米粒子如何催化化学反应的原子级洞察对于优化化学转化过程至关重要。众所周知，负载的金属纳米粒子表面原子的不同几何构型具有不同的催化反应性，并且活性物质的吸附可以引起金属表面的重建。因此，在原子尺度的反应条件下表征金属表面结构对于理解反应性至关重要。对高表面积氧化物负载的金属纳米粒子的这种见解的阐明受到低于原子分辨率的限制，该分辨率通常在实际条件下操作时由环境透射电子显微镜 (TEM) 实现，并且缺乏提供有关暴露分布的定量信息的相关实验测量。相关反应条件下的表面原子。我们通过将吸附物诱导的表面重建的密度泛函理论预测与原位 TEM 的原子分辨成像在视觉上相关联，并通过原位红外光谱对表面原子配置的样品平均测量进行定量，所有这些都在相同的饱和吸附质覆盖范围内，从而克服了这些限制。这在饱和覆盖和升高（> 400 K）温度下由 CO 吸附诱导的铂 (Pt) 纳米颗粒表面重建得到证明，这与催化转化器中冷启动条件下的 CO 氧化反应有关。通过我们的相关方法，观察到裸 Pt 纳米粒子采用的截断八面体形状由于饱和 CO 覆盖而经历可逆的小面选择性重建，其中 {100} 小面粗糙化为相邻的阶梯式高米勒指数小面，而 {111} 小面保持不变。