Michiels Roel, Gerrits Nick, Neyts Erik, Bogaerts Annemie
Research group PLASMANT, Department of Chemistry, University of Antwerp, Universiteitsplein 1, Wilrijk,Antwerp BE-2610, Belgium.
Leiden Institute of Chemistry, Gorlaeus Laboratories, Leiden University, P.O. Box 9502, Leiden 2300 RA, The Netherlands.
J Phys Chem C Nanomater Interfaces. 2024 Jul 1;128(27):11196-11209. doi: 10.1021/acs.jpcc.4c02193. eCollection 2024 Jul 11.
Plasma catalysis is an emerging technology, but a lot of questions about the underlying surface mechanisms remain unanswered. One of these questions is how important Eley-Rideal (ER) reactions are, next to Langmuir-Hinshelwood reactions. Most plasma catalysis kinetic models predict ER reactions to be important and sometimes even vital for the surface chemistry. In this work, we take a critical look at how ER reactions involving H radicals are incorporated in kinetic models describing CO hydrogenation and NH synthesis. To this end, we construct potential energy surface (PES) intersections, similar to elbow plots constructed for dissociative chemisorption. The results of the PES intersections are in agreement with molecular dynamics (AIMD) findings in literature while being computationally much cheaper. We find that, for the reactions studied here, adsorption is more probable than a reaction via the hot atom (HA) mechanism, which in turn is more probable than a reaction via the ER mechanism. We also conclude that kinetic models of plasma-catalytic systems tend to overestimate the importance of ER reactions. Furthermore, as opposed to what is often assumed in kinetic models, the choice of catalyst will influence the ER reaction probability. Overall, the description of ER reactions is too much "ideal" in models. Based on our findings, we make a number of recommendations on how to incorporate ER reactions in kinetic models to avoid overestimation of their importance.
等离子体催化是一项新兴技术，但关于其潜在表面机制的许多问题仍未得到解答。其中一个问题是，与朗缪尔-欣谢尔伍德反应相比，埃利-里德尔（ER）反应有多重要。大多数等离子体催化动力学模型预测ER反应很重要，有时甚至对表面化学至关重要。在这项工作中，我们批判性地审视了涉及氢自由基的ER反应是如何纳入描述一氧化碳加氢和氨合成的动力学模型中的。为此，我们构建了势能面（PES）交叉点，类似于为解离化学吸附构建的肘形图。PES交叉点的结果与文献中的分子动力学（AIMD）研究结果一致，同时计算成本要低得多。我们发现，对于这里研究的反应，吸附比通过热原子（HA）机制的反应更有可能发生，而热原子机制又比通过ER机制的反应更有可能发生。我们还得出结论，等离子体催化系统的动力学模型往往高估了ER反应的重要性。此外，与动力学模型中通常假设的情况相反，催化剂的选择会影响ER反应概率。总体而言，模型中对ER反应的描述过于“理想化”。基于我们的研究结果，我们就如何在动力学模型中纳入ER反应以避免高估其重要性提出了一些建议。
