Combustion Research Facility researchers Chris Kliewer, Judit Zádor, Shinae Kim and Eric Smoll published a paper in “The Journal of Physical Chemistry C” on “Automated Theoretical Investigation of the Ammonia Decomposition Reaction Network on Pt(111)”.
In this work, the authors mapped out the potential energy surfaces of ammonia decomposition and diffusion reactions on Pt(111) by using an automated tool (Pynta). They identified several stable adsorption sites and various pathways for the reactions, which can differ by more than 0.5 eV depending on the configuration, emphasizing the importance of a systematic search. They found that the associative desorption of N* to form N2 gas to be the rate-determining step due to its high reaction barrier on Pt(111). They constructed a microkinetic model based on the lowest-energy configurations. Their simulations show that under the chosen conditions there is a high concentration of N* at temperatures greater than 750 K, with some contribution to the high coverage from NH2* between 650 and 750 K, signaling the importance of coverage dependence. They also calculated the diffusion rate coefficient of all bound reaction intermediates. Their site-specific calculations can form the basis for future kinetic Monte Carlo calculations.
For more details, visit https://doi.org/10.1021/acs.jpcc.6c01174