A perspective on the future of electrochemical ammonia synthesis: aqueous or non-aqueous?

Abstract

Ammonia (NH₃) production is deemed to address the hunger issues of the drastically mounting population due to its huge significance in the fertilizer industry. The quest is ongoing to reduce the CO₂ emissions and energy consumption by traditional Haber–Bosch process for bulk ammonia production in industries. The most promising alternative to the same is electrochemical ammonia production, which leads to zero carbon emission, can be operated under mild conditions, and is energy efficient. Unfortunately, the faradaic efficiency (FE) and ammonia yield rate are far below the practical standards, and only a few breakthrough works are available in the literature with more than 50% FE. In past years, the majority of the research has grown in view of the development of electrocatalysts to enhance the FE and yield rates. Although the design of the electrode is crucial to determine the performance of the overall process, the effect of electrolyte and synergy between electrolyte and electrode is equally important but underexplored. So, in this perspective, we summarize the breakthrough works in electrochemical ammonia production under both aqueous and non-aqueous environments. Besides, different strategies and modifications in electrolytes, electrode–electrolyte interface have been discussed that may lead to a decisive interpretation of “the actual future of ammonia production, i.e., either aqueous or non-aqueous?” based on their existing challenges and future potential for real-time application and industrialization. In the end, the overall outlook and future opportunities in this regard have been proposed, deliberating a stern remark on the underlooked aspects in this field. This perspective will open a floor for further investigations and improvements in aqueous and non-aqueous ammonia production capable of meeting the practical standards and a green revolution.