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首页> 外文期刊>The journal of physical chemistry, C. Nanomaterials and interfaces >Investigation of gold-silver, gold-copper, and gold-palladium dimers and trimers for hydrogen peroxide formation from H-2 and O-2
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Investigation of gold-silver, gold-copper, and gold-palladium dimers and trimers for hydrogen peroxide formation from H-2 and O-2

机译：研究从H-2和O-2形成过氧化氢的金银，金铜和金钯二聚体和三聚体

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Direct synthesis of H2O2 from H-2 and O-2 is a reaction of commercial interest. In addition, this reaction is likely to occur in situ during gas-phase propylene epoxidation using H-2 and O-2 on Au/Ti-based catalysts. To consider the effect of alloying on H2O2 formation on Au-containing clusters, we have performed a B3LYP-based density functional theory analysis of H2O2 formation from H-2 and O-2 on Ag, Ag-Au, Cu, Cu-Au, Pd, and Pd-Au dimers and trimers. The LANL2DZ pseudopotential and the corresponding double-zeta basis set was used for heavy atoms, while a 6-311+G(3df) basis set was used for O and H. We report kinetic and thermodynamic parameters at standard conditions (298.15 K, 1 atm) for following elementary steps: (1) molecular adsorption of O-2, (2) first H-2 addition to make the hydroperoxy (OOH) species, and (3) second H-2 addition to make H2O2. Formation of the OOH species is thermodynamically (and in some cases kinetically) unfavorable on all the Cu- and Ag-containing dimers. Although the kinetics is favorable, formation of the OOH species is thermodynamically unfavorable on all the Cu- and Ag-containing trimers except CuAu2. The H2O2 formation step is, however, thermodynamically unfavorable on CuAu2. Contradictory to findings on pure Au clusters, we predict that the H2O2 formation on small Ag, Ag-Au, Cu, and Cu-Au clusters is not feasible mainly due to the unfavorable thermodynamics (298.15 K, 1 atm) of the H-2 addition steps. These predictions are also applicable to Pd-2, Pd2Au, and PdAu2 clusters. On the other hand, formation of the OOH and H2O2 species is both kinetically and thermodynamically favorable on PdAu and Pd-3 clusters. Thus, on the basis of computational screening of the catalytic activity of fifteen pure and Au-alloy dimers and trimers reported here, in addition to Au-3, we identify PdAu and Pd-3 as potentially active clusters for OOH and H2O2 formation from H-2 and O-2.
机译：由H-2和O-2直接合成H2O2是商业利益的反应。另外，该反应很可能在Au / Ti基催化剂上使用H-2和O-2在气相丙烯环氧化期间原位发生。为考虑合金化对含Au团簇上H2O2形成的影响，我们已经进行了基于B3LYP的密度泛函理论分析，分析了H-2和O-2在Ag，Ag-Au，Cu，Cu-Au， Pd和Pd-Au二聚体和三聚体。 LANL2DZ伪电势和相应的double-zeta基础集用于重原子，而6-311 + G（3df）基础集用于O和H。我们报告标准条件下的动力学和热力学参数（298.15 K，1 atm）进行以下基本步骤：（1）O-2的分子吸附，（2）首先添加H-2以形成氢过氧（OOH）物种，以及（3）第二个H-2添加以形成H2O2。在所有含铜和银的二聚体上，热力学上（在某些情况下是动力学上）不利于形成OOH。尽管动力学是有利的，但除了CuAu2外，在所有含Cu和Ag的三聚体上OOH物种的形成在热力学上都是不利的。但是，H2O2的形成步骤在热力学上不利于CuAu2。与纯金团簇的发现相反，我们预测在小银团，银金团簇，铜团和铜金团簇上形成H2O2是不可行的，这主要是由于H-2的热力学不利（298.15 K，1 atm）添加步骤。这些预测也适用于Pd-2，Pd2Au和PdAu2簇。另一方面，在PdAu和Pd-3团簇上，OH和H2O2物种的形成在动力学和热力学上都是有利的。因此，根据对此处报道的十五种纯和金合金二聚体和三聚体的催化活性的计算筛选，除Au-3外，我们还将PdAu和Pd-3鉴定为可能由氢形成OOH和H2O2的潜在活性簇。 -2和O-2。

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