Development of a Novel Catalyst for the Nitrogen Reduction Reaction Using Density Functional Theory

Abstract

The Haber-Bosch process in ammonia production has been present for a long time in the sector of ammonia (NH3) production, but because of the energy costly conditions required in the process such as temperature (100-500o C) and pressure(10-30MPa) a replacement needs to be developed. Currently the electrocatalytic nitrogen reduction reaction (NRR) being able to produce NH3 in ambient conditions stands as the prominent replacement to the Haber-Bosch process. Yet, it still lacks the competency due to low faradaic efficiencies and competition from the hydrogen evolution reaction (HER). Two-dimensional metal-organic frameworks (2D MOFs) can be used as platforms to derive single-atom catalysts (SACs) where the active metal centers are utilized up to 100% in the NRR, and SACs have the ability to suppress the HER. This thesis outlines the use of DFT to screen a new series of TM-Tp 2D MOFs (where Tp = 1,3,5 -triformylphloroglucinol; TM = Cu, Ni, Cr, Mo, Os, Ru, and W) for the NRR. Two screening stages were used based on the criteria of activating the N2 molecule and stabilizing the NNH intermediate. In the first screening step Mo -Tp, Cr-Tp, and Ni-Tp were screened out by having the lowest free energy change values of N2 adsorption. In a second screening process, Mo-Tp was screened out at the end. The NRR mechanism was investigated which showed a low limiting potential of -0.38V via the distal pathway. Moreover, the Mo-Tp monolayer proved to possess excellent thermal and structural stability. Finally, the electronic structure of the monolayer was analyzed to study the N2 adsorption process.

Date of Award	6 Dec 2023
Original language	American English
Supervisor	Ali AlHammadi (Supervisor)