Fajín José L C, Cordeiro Maria Natália D S
LAQV@REQUIMTE, Department of Chemistry and Biochemistry, Faculty of Sciences, University of Porto, P-4169-007 Porto, Portugal.
Nanomaterials (Basel). 2022 Jan 25;12(3):394. doi: 10.3390/nano12030394.
In this study, the full reaction mechanism for NO hydrogenation on silver doped Au(210) surfaces was investigated in order to clarify the experimental observations. Density functional theory (DFT) calculations were used to state the most favorable reaction paths for individual steps involved in the NO hydrogenation. From the DFT results, the activation energy barriers, rate constants and reaction energies for the individual steps were determined, which made it possible to elucidate the most favorable reaction mechanism for the global catalytic process. It was found that the NO dissociation occurs in surface regions where silver atoms are present, while hydrogen dissociation occurs in pure gold regions of the catalyst or in regions with a low silver content. Likewise, NO dissociation is the rate determining step of the global process, while water formation from O adatoms double hydrogenation and N and HO desorptions are reaction steps limited by low activation energy barriers, and therefore, the latter are easily carried out. Moreover, water formation occurs in the edges between the regions where hydrogen and NO are dissociated. Interestingly, a good dispersion of the silver atoms in the surface is necessary to avoid catalyst poison by O adatoms accumulation, which are strongly adsorbed on the surface.
在本研究中，为了阐明实验观察结果，对银掺杂的Au(210)表面上NO加氢的完整反应机理进行了研究。采用密度泛函理论(DFT)计算来确定NO加氢过程中各个步骤最有利的反应路径。根据DFT结果，确定了各个步骤的活化能垒、速率常数和反应能，从而有可能阐明整个催化过程最有利的反应机理。研究发现，NO解离发生在存在银原子的表面区域，而氢解离发生在催化剂的纯金区域或银含量低的区域。同样，NO解离是整个过程的速率决定步骤，而由O吸附原子的双氢化形成水以及N和HO的脱附是受低活化能垒限制的反应步骤，因此，后者很容易进行。此外，水的形成发生在氢和NO解离区域之间的边缘。有趣的是，表面银原子的良好分散对于避免因O吸附原子的积累而导致催化剂中毒是必要的，因为O吸附原子会强烈吸附在表面。
