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Harnessing Plasma Environments for Ammonia Catalysis: Mechanistic Insights from Experiments and Large-Scale Ab-initio Molecular Dynamics

preprint
submitted on 28.11.2020, 04:39 and posted on 01.12.2020, 07:36 by Sharma Yamijala, Giorgio Nava, Zulfikhar A. Ali, Davide Beretta, Bryan Wong, Lorenzo Mangolini
By combining experimental measurements with ab initio molecular dynamics simulations, we provide the first microscopic description of the interaction between metal surfaces and a low-temperature nitrogen-hydrogen plasma. Our study focuses on the dissociation of hydrogen and nitrogen as the main activation route. We find that ammonia forms via an Eley-Rideal mechanism where atomic nitrogen abstracts hydrogen from the catalyst surface to form ammonia on an extremely short timescale (a few picoseconds). On copper, ammonia formation occurs via the interaction between plasma-produced atomic nitrogen and the H-terminated surface. On platinum, however, we find that surface saturation with NH groups is necessary for ammonia production to occur. Regardless of the metal surface, the reaction is limited by the mass transport of atomic nitrogen, consistent with the weak dependence on catalyst material that we observe and has been reported by several other groups. This study represents a significant step towards achieving a mechanistic, microscopic-scale understanding of catalytic processes activated in low-temperature plasma environments.

Funding

U.S. Army Research Office under Grant No. W911NF-17-1-0340

History

Email Address of Submitting Author

usagi@alum.mit.edu

Institution

University of California, Riverside

Country

United States

ORCID For Submitting Author

0000-0002-3477-8043

Declaration of Conflict of Interest

no conflict of interest

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