Ammonia formation on hexagonal Molybdenum Nitride by Langmuir−Hinshelwood Mechanism: a DFT study

By 2030, Ammonia production, worldwide is estimated to increase to 280 million tons. Ammonia is industrially synthesized by Iron-based catalysts through energy intensive Haber-Bosch Reaction. More efficient Ru-based catalysts are also theorized but they are very costly compared to Iron ones. In recent years, scientific community has shown great interest in Molybdenum Nitride as a promising catalyst for ammonia production. Using Density Functional Theory (DFT), we studied the reaction steps involved in the production of Ammonia in Langmuir− Hinshelwood Mechanism. Adsorption characteristics of N2, H2, NH, NH2 and NH3 are explored on hexagonal MoN surface. Using Transition State Theory, we identified possible routes for dissociation of H2 and N2 molecules and hydrogenation of NHx-species (0<x≤2). Role of hydrogen coverage on the surface in minimizing transition barriers was also studied. Our calculations predict that presence of H atoms on the surface decreases the large barriers present for hydrogenation of N species. Our work will contribute to the search of the most suitable catalyst for a very important chemical reaction.