PhD Thesis Defense- Auguste Tetenoire
Dynamics of the photo-induced desorption and oxidation of CO on Ru(0001) with different (O, CO) coverages
March 23, 11:00
CFM Auditorium
Candidate: August Tetenoire
Supervisors: Maite Alducin and J. Iñaki Juaristi
Summary
Carbon monoxide (CO) is a neurotoxic gas emitted for instance in combustion reaction. Therefore, it has been sought for air treatment solutions, where CO oxidation is a straight forward choice. In ultra high vacuum conditions the ruthenium has been found to be very inactive for CO oxidation. Experimentally, it has been shown the opening of a new reaction path for CO oxidation on ruthenium surfaces by means of femtosecond laser irradiation. Accurate simulations of the photo-reaction dynamics are required to give a proper characterization of this kind of experiments.
This thesis is dedicated to the study of the photo-induced desorption and oxidation of CO molecules, coadsorbed with oxygen (O) adatoms on Ru(0001) with different surface coverages.
We began with the characterization of three (O, CO) mixed surface coverages on Ru(0001). We first found the adsorption configuration of minimum energy for each surface coverage, then we computed the desorption potential of a CO molecule, and found the minimum energy path to CO oxidation on all three surface coverages.
Then, we ran ab-initio molecular dynamics with electronic friction simulations, and we have been able to show the complexity of the reaction path to oxidize the CO molecule, and explain its low probability of occurrence.
Next, we showed the importance of surface deformations on the desorption and oxidation probabilities of CO, and on the adsorbate motion. Then, we presented in detail and characterized the different mechanisms of CO oxidation.
Finally, we created a potential energy surface based on neural networks and showed that it is a very promising tool to solve the problem of the computational cost of ab-initio molecular dynamics simulations.
Figure: Representation of the three surface coverages under study, named: (a) Low, (b) Intermediate and (c) High. The spheres represent the atoms, and the color attributed to the elements are: The Ru in blue, the O in red and the C in grey. In the left panels are represented the top views of the coverages, with in black the representation of the simulation cell. In the right panels are represented the side views of the coverages.