Quantitative analysis of ammonia was conducted using 1 H NMR spectroscopy, following a previously published protocol that ensures the measured NH3 arises from electrochemical N2 reduction and not from air or other potential contamination sources . The triplet peak associated with ammonia containing the most abundant 14 N2 isotope (spin 1 nucleus) appears at 6.83 ppm with a coupling constant of 96 Hz as shown in Figure . The resulting spectra for the postelectrolyte samples at different current densities are depicted in Figure . Isotope labelling and rigorous control experiments were performed to ensure that NH3 is produced by the electrochemical reduction of N2 and not from contaminants. Isotope labeling experiments were conducted at a current density of -45 mA/cm², as this condition resulted in the highest ammonia current density. The isotope-labeled samples were quantified using ¹H NMR, as shown in Figures and. These experiments yielded a Faradaic Efficiency (FE) of 25.15 ± 1.01%, with an ammonia current of 11.4 mA/cm² at -45 mA/cm². The NMR spectrum of ammonia generated from ¹⁵N₂ displays a characteristic doublet at 6.67 ppm, with a coupling constant of 96 Hz. UV-vis spectrometry was also used for quantification through the indophenol method. Both UV-vis and NMR were benchmarked and produced consistent results. The method of additions was employed to accurately determine the ammonia, as detailed in the SI. The post-electrolysis catalyst was characterized using Scanning Electron Microscopy with Energy Dispersive X-ray Spectroscopy (SEM-EDS) and X-ray Photoelectron Spectroscopy (XPS) on the post-reaction sample, as illustrated in Figure 6. In Figure , a high-resolution XPS scan of the post-electrolysis electrode, confirming the presence of Mg⁰ (1s) is shown, which strengthens the evidence of magnesium deposition during the electrochemical process. Similarly, Figure shows a high-resolution XPS scan confirming the presence of Mg⁰ (2p), providing further verification of magnesium deposition on the electrode surface. To resolve the uncertainty in XPS analysis about whether nitrogen signals originated from nitride formation or the nitrogen in DMF, a 0.5 mm Ni foam sample was carefully prepared. This material was chosen because it could easily release any residual DMF at high temperatures and didn't retain a wet appearance. Magnesium was coated onto the Ni foam, and nitrogen gas (N₂) was bubbled continuously to encourage nitride formation. To protect the nitride layer from reacting with air, a thin layer of copper was deposited onto the Ni foam. The sample was then dried in a vacuum oven for 96 hours to ensure all traces of DMF were removed. Finally, a depth profile analysis was carried out to examine the SEI layers beneath the copper coating. Depth-profile XPS measurements were conducted to investigate the composition of the post-electrolysis catalyst using synchrotron-based XPS at the Advanced Light Source (ALS) at Lawrence Berkeley National Laboratory, specifically at beamlines 9.3.2 and 9.3.1. Tender X-rays with a photon energy of 4000 eV provided information from a depth of approximately 10-12 nm below the surface (Figure ), while soft X-rays probed at a shallower depth of ~2-4 nm (Figure ).