Figure presents a comparison of FEs, ammonia current density and total cell voltage for Li-NRR, Ca-NRR, and Mg-NRR. For Mg and Li, we observed that an increase in total current density correlates with a proportional increase in ammonia production rate, while the FE for ammonia remains constant. This indicates that the NH3 FE is independent of the applied current densities and the total cell potential for the configuration used. This also suggests that the same ammonia FE can be maintained even at higher current densities. Ca-NRR also shows significant potential with good ammonia selectivity, although further work is needed to enhance both the ammonia current density and FE. Mg-NRR, while promising, still requires in-depth research to achieve comparable FEs and current densities. When analyzing the applied potential trends for lithium, magnesium, and calcium in electrochemical systems, calcium exhibits higher potentials, primarily due to the lower salt concentration (around 0.5M calcium perchlorate) used in the system. Salt concentration plays a crucial role in electrochemical performance, as higher concentrations improve ion mobility, reduce solution resistance, and minimize ohmic losses. However, excessively high concentrations can increase solution viscosity, leading to higher resistance and degraded performance. For instance, in the LiNRR system, using LIBF4 at concentrations of 1M to 3M significantly improved performance, but a 4M concentration caused performance degradation due to increased viscosity. Identifying the optimal salt concentration is therefore critical for achieving the best performance while managing costs, as higher salt concentrations can raise system expenses. Although a 1M calcium perchlorate solution resulted in lower Faradaic efficiency (FE), the 0.5M concentration was ultimately chosen as optimal due to its balance of performance and practicality. For lithium, a 2M concentration of lithium salt proved to be optimal, leading to a slightly lower applied potential compared to calcium systems. In the case of magnesium, a 1M concentration of magnesium perchlorate was initially employed in the previous study . However, after 24 hours, the solution began to crystallize, prompting a reduction in concentration to 0.5 M. This adjustment prevented salt crystallization and ensured the solution remained well-mixed even 24 hours after the operation was completed. Comparable performance was achieved using 0.5 M magnesium perchlorate, which also demonstrated the lowest applied potential while maintaining satisfactory faradaic efficiencies (FEs). Among the three cations (Ca, Mg, and Li), magnesium emerges as the most promising mediator for ammonia synthesis. With a 0.5M concentration of magnesium perchlorate, it exhibits the low applied potential while maintaining high FEs. Mg shows significant potential for optimization due to its favorable characteristics, such as a lower energy input compared to lithium and the ability to achieve relatively high FE under certain conditions. These traits suggest that, with further investigation and refinement of the reaction system, magnesium could become a promising candidate for efficient and sustainable ammonia synthesis. Furthermore, we observed that the working potential for Mg-NRR is relatively lower compared to Li-NRR and Ca-NRR, which aligns well with our hypothesis of a reduced plating potential for Mg. Notably, with Mg-NRR, we successfully synthesized ammonia at a working electrode potential as low as 3V.