Leiden Institute of Chemistry, Leiden University, P.O. Box 9502, 2300 RA Leiden, The Netherlands.
Faculty of Industrial Engineering, Mechanical Engineering and Computer Science, University of Iceland, VR-III, 107 Reykjavík, Iceland and University of Otago, P.O. Box 56, Dunedin 9054, New Zealand.
Phys Chem Chem Phys. 2019 Aug 21;21(31):17142-17151. doi: 10.1039/c9cp02330e. Epub 2019 Jul 24.
In this work we compute high-coverage hydrogen adsorption energies and geometries on the stepped platinum surfaces Pt(211) and Pt(533) which contain a (100)-step type and the Pt(221) and Pt(553) surface with a (111) step edge. We discuss these results in relation to ultra-high-vacuum temperature programmed desorption (TPD) data to elucidate the origin of the desorption features. Our results indicated that on surfaces with a (100)-step type, two distinct ranges of adsorption energy for the step and terrace are observed, which mirrors the TPD spectra for which we find a clear separation of the desorption peaks. For the (111) step type, the TPD spectra show much less separation of the step and terrace features, which we assign to the low individual adsorption energies for H atoms on this step edge. From our results we obtain a much clearer understanding of the surface-hydrogen bonding at high coverages and the origin of the different TPD features present for the two step types studied.
在这项工作中，我们计算了高覆盖率下氢在阶梯状铂表面 Pt(211) 和 Pt(533)（包含 (100) 型阶梯）以及 Pt(221) 和 Pt(553)（具有 (111) 型阶梯边缘）上的吸附能和几何构型。我们讨论了这些结果与超高真空程序升温脱附（TPD）数据之间的关系，以阐明脱附特征的起源。我们的结果表明，在具有 (100) 型阶梯的表面上，观察到阶梯和平台的吸附能有两个明显的范围，这与 TPD 谱相对应，我们发现脱附峰有明显的分离。对于 (111) 型阶梯，TPD 谱显示出阶梯和平台特征的分离程度要小得多，我们将其归因于该阶梯边缘上 H 原子的单个吸附能较低。通过我们的结果，我们对高覆盖率下的表面氢键以及所研究的两种阶梯类型的不同 TPD 特征的起源有了更清晰的认识。
