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首页> 外文期刊>Physical chemistry chemical physics: PCCP >A first-principles investigation of the effect of Pt cluster size on CO and NO oxidation intermediates and energetics
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A first-principles investigation of the effect of Pt cluster size on CO and NO oxidation intermediates and energetics

机译：铂簇大小对一氧化碳和一氧化氮中间体和能量的影响的原理研究

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As catalysis research strives toward designing structurally and functionally well-defined catalytic centers containing as few active metal atoms as possible, the importance of understanding the reactivity of small metal clusters, and in particular of systematic comparisons of reaction types and cluster sizes, has grown concomitantly. Here we report density functional theory calculations (GGA-PW91) that probe the relationship between particle size, intermediate structures, and energetics of CO and NO oxidation by molecular and atomic oxygen on Pt_x clusters (x = 1-5 and 10). The preferred structures, charge distributions, vibrational spectra, and energetics are systematically examined for oxygen (O2, 20, and O), CO, CO2, NO, and NO2, for CO/NO co-adsorbed with O2, 20, and O, and for CO2/NO2 co-adsorbed with O. The binding energies of oxygen, CO, NO, and of the oxidation products CO2 and NO2 are all markedly enhanced on Pt_x compared to Pt(111), and they trend toward the Pt(111) levels as cluster size increases. Because of the strong interaction of both the reactants and products with the Pt_x clusters, deep energy sinks develop on the potential energy surfaces of the respective oxidation processes, indicating worse reaction energetics than on Pt(111). Thus the smallest Pt clusters are less effective for catalyzing CO and NO oxidation in their original state than bulk Pt. Our results further suggests that oxidation by molecular O2 is thermodynamically more favourable than by atomic O on Pt_x. Conditions and applications in which the Pt_x clusters may be effective catalysts are discussed.
机译：随着催化研究努力设计包含尽可能少的活性金属原子的结构和功能明确的催化中心，随之而来的是理解小金属簇的反应性，尤其是反应类型和簇大小的系统比较的重要性。 。在这里，我们报告了密度泛函理论计算（GGA-PW91），该算法探讨了粒径，中间结构以及Pt_x团簇（x = 1-5和10）上的分子氧原子和原子氧氧化CO和NO的能级之间的关系。系统检查了优选的结构，电荷分布，振动光谱和高能学，以检查氧气（O2、20和O），CO，CO2，NO和NO2，与O2、20和O共吸附的CO / NO，与Pt（111）相比，Pt_x上的氧，CO，NO以及氧化产物CO2和NO2的结合能均显着增强，并且趋向于Pt（111）。 ）级别随着群集大小的增加而增加。由于反应物和产物与Pt_x团簇之间的强相互作用，在相应氧化过程的势能表面上会形成深能量阱，这表明反应能级比Pt（111）差。因此，最小的Pt团簇在原始状态下催化CO和NO氧化的效率不如本体Pt。我们的结果进一步表明，在分子动力学上，O2的氧化比Pt_x上的原子O的氧化更有利。讨论了Pt_x团簇可能是有效催化剂的条件和应用。

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