阳离子Pt位点在Pt4 / Pt（111）和Pt4 / CeO2（111）基质上水和乙醇的吸附特性中的作用：密度泛函理论研究,The Journal of Chemical Physics

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阳离子Pt位点在Pt4 / Pt（111）和Pt4 / CeO2（111）基质上水和乙醇的吸附特性中的作用：密度泛函理论研究
The Journal of Chemical Physics ( IF 3.1 ) Pub Date : 2016-09-29 12:39:17 , DOI: 10.1063/1.4963162
Yohanna Seminovski ₁ , Polina Tereshchuk ₁ , Adam Kiejna ₂ , Juarez L. F. Da Silva ₁

Affiliation

有限部位的铂颗粒，铂_Ñ，支撑在减少或未还原的氧化铈表面，即，的CeO _{2- X}（111），已经采用和研究作为催化剂用于宽的应用范围，其中包括生产氢（0 <12）使用乙醇蒸汽重整工艺。近年来，我们对Pt与CeO _{2− x}相互作用的原子级理解得到了提高。然而，对Pt _n / CeO _{2- x}（111）衬底上的活性位点的识别仍远未完成。在这项工作中，我们应用了基于密度泛函理论的计算，并添加了现场库仑相互作用（DFT + U（Pt（111），Pt ₄ / Pt（111），CeO ₂）的活性位和Pt氧化态对水和乙醇（探针分子）吸附特性的影响的研究（111）和Pt ₄ / CeO ₂（111）。我们的结果表明，水和乙醇优先结合在四面体Pt ₄簇基的阳离子位点上，而不是位于簇顶或表面Ce（阳离子）和O（阴离子）上的阴离子低配位Pt原子网站。Pt ₄团簇的存在有助于增加两个分子在Pt（111）和CeO ₂上的吸附能（111）表面；然而，对于Pt ₄ / CeO ₂（111），其幅度增加的幅度较小。因此，阳离子Pt位在水和乙醇的吸附性能中起着至关重要的作用。水和乙醇都通过O原子结合到顶部位置，并分别在Pt（111）和CeO ₂（111）基板上采用平行和垂直构型，而一旦包含Pt ₄团簇，它们的方向就会改变，这有利于H与表面部位结合。

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The role of the cationic Pt sites in the adsorption properties of water and ethanol on the Pt4/Pt(111) and Pt4/CeO2(111) substrates: A density functional theory investigation

Finite site platinum particles, Pt_n, supported on reduced or unreduced cerium oxide surfaces, i.e., CeO_2−x(111) (0<12), have been employed and studied as catalysts for a wide range of applications, which includes hydrogen production using the ethanol steam reforming processes. Our atomic-level understanding of the interaction of Pt with CeO_2−x has been improved in the last years; however, the identification of the active sites on the Pt_n/CeO_2−x(111) substrates is still far from complete. In this work, we applied density functional theory based calculations with the addition of the on-site Coulomb interactions (DFT+U) for the investigation of the active sites and the role of the Pt oxidation state on the adsorption properties of water and ethanol (probe molecules) on four selected substrates, namely, Pt(111), Pt₄/Pt(111), CeO₂(111), and Pt₄/CeO₂(111). Our results show that water and ethanol preferentially bind in the cationic sites of the base of the tetrahedron Pt₄ cluster instead of the anionic lower-coordinated Pt atoms located on the cluster-top or in the surface Ce (cationic) and O (anionic) sites. The presence of the Pt₄ cluster contributes to increase the adsorption energy of both molecules on Pt(111) and CeO₂(111) surfaces; however, its magnitude increases less for the case of Pt₄/CeO₂(111). Thus, the cationic Pt sites play a crucial role in the adsorption properties of water and ethanol. Both water and ethanol bind to on-top sites via the O atom and adopt parallel and perpendicular configurations on the Pt(111) and CeO₂(111) substrates, respectively, while their orientation is changed once the Pt₄ cluster is involved, favoring H binding with the surface sites.

更新日期：2016-09-30

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