The growing risk of a potential energy crisis and escalating environmental challenges highlight the inminet need for research focused on alternative, sustainable energy sources capable of substituting fossil fuels. Ammonia (NH₃) has been extensively produced and utilised as a fertiliser for over a century. Currently, due to its significant hydrogen content (17.6% wt), high energy density (4.32 kW h L−1 for liquid NH₃), easy liquefaction for handling, storage and transportation, it is gaining momentum as a promising alternative renewable energy carrier and storage intermediate for global use in the future. [1-3] NH₃ is produced via the well-established Haber-Bosch process (HBP) [1], which is well known for its high energy demands that consume 1-2% of fossil fuels worldwide, contributing to the greenhouse effect by releasing the equivalent of ca. 2% of total CO₂ global emissions. [4-6] Therefore, the development of greener and more sustainable technologies to replace the century-old Haber-Bosch process is imperative. The electrochemical reduction reaction of nitrogenous spices (E-NRR) is a suitable technology widely recognised as an alternative option to the traditional HBP. E-NRR offers several key benefits:: (i) it is thermodynamically predicted to be more energy efficient than the HBP by 20%; (ii) it permits the elimination of fossil fuels as H₂ source; (iii) it can be integrated with renewables energy resources (e.g. solar panel, windmill, etc.); (4) it is scalable and can lead to on-demand & on-site NH₃ production. [4] Thus far, research on E-NRR has mostly focused on the electrocatalyst; however, it is well known that the electrolyte plays a crucial role, potentially having an impact of several orders of magnitude on the process outcome, particularly affecting selectivity and efficiency. In E-NRR the optimal electrolyte should enhance N₂ solubility, limit the H⁺ to minimize the parasitic hydrogen evolution reaction (HER), maintain the catalyst stability, and thus improve the Faradic efficiency (FE). The types of proton donors, solvents and additives, such as alkali metal ions, are critical in enhancing the selectivity of the E-NRR process.

In this context, the present work aims to explore the use of glycerol-water mixture in different proportions as a solvent in the electrolyte to study the potential beneficial effect of glycerol in terms of N₂ solubility increment and HER mitigation. Furthermore, it has been demonstrated that Nafion membranes, usually used as separators on E-NRR systems, represent an important source of NH₃ impurities, leading to false positives or overestimation of the NH₃ production. Taking that into account, a set of experiments has been performed to elucidate the membrane-ammonia interactions and quantify the impurities in our system.