Advancements in quantum chemistry computer codes and, more recently, machine learning have significantly evolved the modelling of gas-surface dynamics, enhancing both accuracy and complexity [1]. This progress has primarily focused on comparing simulation results with well-defined molecular beam experiments. However, in various research areas and technological applications, decades-old simple models relying on simple assumptions and empirical data still predominate.
One notable example is the Fridman-Macheret (FM) α model. This has been employed to quantify the increase in turnover frequencies (TOFs) in plasma-assisted over conventional (temperature-driven) heterogeneous catalysis, fostering hopes for a more sustainable alternative that can be easily scaled up. A specific focus has been on ammonia synthesis and vibrationally excited states available in the plasma, as the dissociative chemisorption of N₂ molecules on a metal catalyst typically constitutes the rate-limiting step. Prevalent micro-kinetic modelling based on transition state theory (TST) for reaction rates necessitates the extension by introducing vibrational-state-dependent rate constants. In this regard, Mehta et al. postulated in their pioneering work [2] that the computationally efficient TST+FM-α model commonly used for reactions in the gas phase can also describe the effect of vibrational excitations on surface reactions.
In this talk, I will concentrate on the dissociative chemisorption (DC) of N₂ on Ru(0001), for which we have recently investigated the impact of vibrational excitations on the surface reactivity. Utilising state-of-the-art gas-surface dynamical modelling that incorporates explicit energy exchange with the surface [3,4], we have computed DC rate coefficients under both thermal and plasma conditions. Our findings indicate that the TST+FM-α model is incapable of accurately describing the vibrationally enhanced dissociation and analyse the implications thereof on TOFs [5].
References
[1] G.-J. Kroes and J. Meyer,Chem. Sci. 16, 480 (2025).
[2] P. Mehta,P. Barboun, F. A. Herrera, J. Kim, P. Rumbach, D. B. Go, J. C. Hicks, and W. F. Schneider,
Nat. Catal.1, 269 (2018).
[3]K. Shakouri, J. Behler, J. Meyer, and G.-J. Kroes,J. Phys. Chem. Lett. 8, 2131 (2017).
[4] P. Spiering, K. Shakouri, J. Behler, G.-J. Kroes and J. Meyer,J. Phys. Chem. Lett. 10, 2957 (2019).
[5] F. van den Bosch, N. Gerrits and J. Meyer, EES Catal.2025, DOI:10.1039/D5EY00132C,
part of collection: Understanding and new approaches to create synergy between catalysis and plasma
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