Substrate doping: A strategy for enhancing reactivity on gold nanocatalysts by tuning sp bands,The Journal of Chemical Physics

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Substrate doping: A strategy for enhancing reactivity on gold nanocatalysts by tuning sp bands
The Journal of Chemical Physics ( IF 3.1 ) Pub Date : 2015-10-12 13:03:14 , DOI: 10.1063/1.4932944
Nisha Mammen ₁ , Stefano de Gironcoli ₂ , Shobhana Narasimhan ₁

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We suggest that the reactivity of Au nanocatalysts can be greatly increased by doping the oxide substrate on which they are placed with an electron donor. To demonstrate this, we perform density functional theory calculations on a model system consisting of a 20-atom gold cluster placed on a MgO substrate doped with Al atoms. We show that not only does such substrate doping switch the morphology of the nanoparticles from the three-dimensional tetrahedral form to the two-dimensional planar form, but it also significantly lowers the barrier for oxygen dissociation by an amount proportional to the dopant concentration. At a doping level of 2.78%, the dissociation barrier is reduced by more than half, which corresponds to a speeding up of the oxygen dissociation rate by five orders of magnitude at room temperature. This arises from a lowering in energy of the s and p states of Au. The d states are also lowered in energy, however, this by itself would have tended to reduce reactivity. We propose that a suitable measure of the reactivity of Au nanoparticles is the difference in energy of sp and d states.

中文翻译：

底物掺杂：通过调节sp谱带提高金纳米催化剂反应性的策略

我们认为，通过用电子给体掺杂放置其上的氧化物基质，可以大大提高Au纳米催化剂的反应性。为了证明这一点，我们在模型系统上执行密度泛函理论计算，该模型系统由放置在掺杂有Al原子的MgO衬底上的20原子金簇组成。我们表明，这样的衬底掺杂不仅将纳米颗粒的形态从三维四面体形式转换为二维平面形式，而且还通过与掺杂剂浓度成比例的量显着降低了氧离解的势垒。在2.78％的掺杂水平下，离解势垒降低了一半以上，这对应于室温下氧的离解速率提高了五个数量级。Au的s和p状态。在d状态也降低了在能源，然而，这本身会趋于减少的反应。我们建议，Au纳米颗粒反应性的合适度量是sp和d态能量的差异。

更新日期：2015-10-13

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