Nitric oxide hydrogenation is investigated on palladium and gold–palladium alloy crystallites, i.e. the extremity of sharp tip samples aimed at modelling a single catalytic grain. Field ion microscopy and field emission microscopy are used to monitor adsorption and reaction in real time. One-dimensional atom probe and atom probe tomography are used on the same samples to unravel the surface composition of the adsorbed layers and the composition of the very first atomic layers of the Pd–Au surface. At constant NO pressure and at 450 K, the surface composition of the adsorbed layer on Pd samples shows a strong hysteresis behavior when H₂ gas is varied. Under oxidizing conditions, N₂O is formed via the occurrence of surface (NO)₂ dimers. In the presence of Pd–Au alloys, the NO–H₂ interaction comprises a simple NO dissociation causing the formation of surface NO₂ species. On Pd–Au tip samples, atom probe tomography proves the occurrence of significant surface enrichment of palladium atoms in the presence of NO gas, but it is not sufficient to drift the behavior of the surface to that of pure palladium. Accordingly, external control parameters could be changed to tune the surface composition of Pd–Au catalysts and thus their activity and/or selectivity.

中文翻译：

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使用场发射技术对催化过程进行成像和化学探测：Pd和Pd-Au催化剂上的NO加氢研究

对钯和金钯合金微晶进行了一氧化氮加氢研究，即尖锐尖端样品的末端旨在模拟单个催化晶粒。场离子显微镜和场发射显微镜用于实时监测吸附和反应。在同一样品上使用一维原子探针和原子探针层析成像技术来揭示吸附层的表面成分和Pd–Au表面的最先原子层的成分。在恒定的NO压力和450 K下，当H ₂气体变化时，Pd样品上吸附层的表面组成表现出很强的滞后行为。在氧化条件下，通过表面（NO）的出现形成N ₂ O_2个二聚体。在Pd-Au合金存在下，NO-H ₂相互作用包括简单的NO分解，导致表面NO ₂物种的形成。在Pd–Au尖端样品上，原子探针断层扫描证明在存在NO气体的情况下会发生钯原子的明显表面富集，但这不足以使表面的行为漂移为纯钯的行为。因此，可以改变外部控制参数来调节Pd-Au催化剂的表面组成，从而调节其活性和/或选择性。