Clarifying the impacts of surface hydroxyls on CO oxidation on CeO2(100) surfaces: a DFT+U study,Physical Chemistry Chemical Physics

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Clarifying the impacts of surface hydroxyls on CO oxidation on CeO2(100) surfaces: a DFT+U study
Physical Chemistry Chemical Physics ( IF 2.9 ) Pub Date : 2020/03/09 , DOI: 10.1039/d0cp00204f
Hui Zhou _{1,

2,

3,

4,

5} , Dong Wang _{1,

2,

3,

4,

5} , Xue-Qing Gong _{1,

2,

3,

4,

5}

Affiliation

In heterogeneous catalysis, surface hydroxylation is well recognized as a common phenomenon under realistic reaction conditions. However, even for the versatile ceria-based materials that have attracted extensive studies, the results and causes of the hydroxyl effect on the catalytic reactivity remain largely elusive. In this work, density functional theory calculations corrected by on-site Coulomb interaction were conducted to clarify the CO oxidation pathways and also the impacts of surface hydroxyls on the catalytic performance at the two most stable reconstructions of CeO₂(100). It is found that the presence of hydroxyl groups can boost the CO oxidation activity on the O-terminal surface but shows an opposite effect on the CeO₄-terminal one. Further analyses regarding the structural distortions, electronic structures and orbital interactions reveal that the stretched Ce–O distance via in-plane hydrogen bonds and the electron redistributions induced by additional hydroxyl coordination are the main reasons for the different hydroxyl effects on the O- and CeO₄-terminal surfaces. Our results not only uncover the dual-character of surface hydroxyls in heterogeneous catalysis, but they also underline the significance of moderate moisture in the reaction system that may endow ceria catalysts with both good thermostability and high catalytic activity.

中文翻译：

澄清表面羟基对CeO2（100）表面CO氧化的影响：DFT + U研究

在非均相催化中，在实际反应条件下，表面羟基化是公认的普遍现象。然而，即使对于已经广泛研究的通用的基于二氧化铈的材料，羟基对催化反应性的影响的结果和原因仍然难以捉摸。在这项工作中，进行了通过现场库仑相互作用校正的密度泛函理论计算，以阐明CO的氧化途径以及表面羟基对CeO ₂的两种最稳定重构的催化性能的影响（100）。发现羟基的存在可以增强O-末端表面上的CO氧化活性，但是对CeO ₄却显示相反的作用-一号航站楼。关于结构畸变，电子结构和轨道相互作用的进一步分析表明，通过面内氢键延伸的Ce-O距离以及由额外的羟基配位引起的电子再分布是羟基对O-和CeO不同影响的主要原因₄端子表面。我们的结果不仅揭示了多相催化中表面羟基的双重特征，而且还强调了反应体系中适度水分的重要性，这可能赋予二氧化铈催化剂良好的热稳定性和高催化活性。

更新日期：2020-04-15

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