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O: Fachverband Oberflächenphysik
O 4: Metal & Semiconductor substrates: Adsorption and reaction of small molecules I
O 4.5: Vortrag
Montag, 9. März 2026, 11:30–11:45, HSZ/0401
Surface effects during plasma-activated nitrogen splitting for catalytic ammonia formation — •Sabine Auras and Roland Bliem — ARCNL, Amsterdam, The Netherlands
Plasma-assisted catalysis (PAC) enables the activation of stable molecules, e.g. N2 or CO2, by generating reactive species that interact with a catalyst, thereby lowering dissociation barriers and creating new reaction pathways. For ammonia synthesis, PAC is particularly attractive as it can operate under milder conditions than the conventional Haber-Bosch process, potentially improving efficiency while reducing energy input. However, plasma fundamentally alters the reaction environment, which limits the applicability of concepts from thermal catalysis. Therefore, in-situ studies of surface properties and adsorbate evolution are needed to understand the surface chemistry under plasma conditions. Here, we present the first in situ XPS data of Ru and Rh surfaces during N2 plasma exposure, as well as mixed N2/H2 plasmas. To correlate surface processes and plasma properties, we further characterize the plasma composition by optical emission spectroscopy and monitor gas-phase products using mass spectrometry. The results reveal distinct differences in how activated N2 species interact with the catalytic surface. This allows us to identify surface intermediates, assess reaction kinetics, and propose a mechanism for NH3 formation, taking into account the role of different plasma species. Our findings highlight the need for a combined approach to identify the role that plasma and catalytic surfaces play - and thus to understand the interactions driving plasma-assisted catalysis.
Keywords: plasma-activated catalysis; surface reaction; reaction mechanism; in-situ XPS; ammonia formation