Alternative reaction mechanisms of ammonia reduction of iron oxide examined using density functional theory modelling

Huanran Wang, Zhezi Zhang, Chiemeka Onyeka Okoye, Xianchun Li, Dongke Zhang

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)

Abstract

Several conceivable mechanisms of NH3 reduction of Fe3O4, represented by the Fe3O4 (001)-B surface, have been hypothesised and examined using density functional theory (DFT) modelling. The proposed reaction mechanisms include NH3 adsorption, NH3 reduction of Fe3O4 to H2O, NH3 dissociation to H2, and NH3 oxidation to NO, with the energy barrier of each reaction calculated. The most likely pathway of NH3 reduction of Fe3O4 to form H2O involves NH3 first adsorbing on an Fe site of the Fe3O4 (001)-B surface. Subsequently, two H atoms are transferred to the adjacent O sites. One H atom from the resulting NH then combines with a surface hydroxyl group to form H2O. For NH3 dissociation into H2, the most probable pathway involves the combination of the H atom from the resulting NH with an H atom from NH3 dehydrogenation adsorbed on the Fe3O4 (001)-B surface to form H2. Fe3O4 reduction creates oxygen vacancies on the surface, which leads to nitrogen migration from the Fe site to these vacancies, forming Fe3N. The adsorbed N atom also bonds with the O atom on the Fe3O4 (001)-B surface to form NO. The activation energy of H2O formation is lower than that of H2 formation on the Fe3O4 (001)-B surface.

Original languageEnglish
Pages (from-to)8341-8351
Number of pages11
JournalNew Journal of Chemistry
Volume49
Issue number20
Early online date16 Apr 2025
DOIs
Publication statusPublished - 16 Apr 2025

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