Plasma Catalysis Modeling: How Ideal Is Atomic Hydrogen for Eley-Rideal?

Area of Science:

• Surface science
• Plasma catalysis
• Chemical kinetics

Background:

• Plasma catalysis is an emerging field with unanswered questions regarding surface reaction mechanisms.
• Eley-Rideal (ER) reactions are often considered crucial in kinetic models, alongside Langmuir-Hinshelwood reactions.

Purpose of the Study:

• To critically evaluate the importance of ER reactions involving H radicals in CO2 hydrogenation and NH3 synthesis.
• To assess the accuracy of current kinetic models in describing ER reaction importance.
• To provide recommendations for improving ER reaction incorporation in plasma catalysis models.

Main Methods:

• Construction of potential energy surface (PES) intersections to analyze reaction pathways.
• Comparison of PES intersection results with ab initio molecular dynamics (AIMD) findings.
• Evaluation of ER, hot atom (HA), and adsorption mechanisms for CO2 hydrogenation and NH3 synthesis.

Main Results:

• PES intersections align with AIMD findings but are computationally less expensive.
• For the studied reactions, adsorption is more probable than HA, which is more probable than ER.
• Kinetic models tend to overestimate the significance of ER reactions in plasma-catalytic systems.

Conclusions:

• The "ideal" description of ER reactions in current models is inaccurate.
• Catalyst choice significantly influences ER reaction probability, contrary to common assumptions.
• Recommendations are provided to refine kinetic models and avoid overestimating ER reaction importance in plasma catalysis.