There is still a paucity of fundamental understanding about the reaction of ammonia decomposition over TiO, especially the role of water. Herein, FPMD and DFT calculations were used to address this concern. The results reveal that ammonia decomposition in pure ammonia causes the hydroxylation of the surfaces and reduction of the proton acceptor sites, making proton transfer (PT) difficult, increasing the distances between the NH and O sites and changing the adsorption configurations of NH, which are not favourable for accepting protons from NH dissociation. When water is introduced, the local hydrogen bonding environment, consisting of NH and HO with the HO dynamically close to the OH, promotes the increase of the positive charge of H atoms from 0.133 to 1.47 e, which increases the OH bond dipole moment from 1.136 to 1.400 Debye, resulting in the shortening of the H-bond distances between NH and OH (1.858 1.945 Å of only NH) and enlarging the OH bonds (0.980 1.120 Å). This reduces the activation energy barriers of OH deprotonation and causes the surfaces to have low hydroxyl coverage from 0.425 to 0.382 eV. Our study reveals the role of water and provides new insights into ammonia decomposition on TiO.
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http://dx.doi.org/10.1039/d3cp06328c | DOI Listing |
Sensors (Basel)
December 2024
Department of Mechanical Engineering, Stanford University, Stanford, CA 93405, USA.
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Center for Sustainable Future Technologies-CSFT@POLITO, Via Livorno 60, 10144 Torino, Italy.
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Department of Inorganic Chemical Technology and Environment Engineering, Faculty of Chemical Technology and Engineering, West Pomeranian University of Technology in Szczecin, Pułaskiego 10, 70-322 Szczecin, Poland.
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Advanced Catalytic Materials (ACM), KAUST Catalysis Center (KCC), King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia.
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