The application of ionic liquids in the electrocatalytic synthesis of ammonia

<sec><p indent="0mm">Ammonia is a versatile compound that has recently attracted considerable interest as a green hydrogen energy carrier. The ability of ammonia to efficiently store and transport hydrogen, which is essential for the development of sustainable energy systems, makes ammonia’s potential in this field enormous. The conventional method of ammonia synthesis, namely the Haber-Bosch process, is energy intensive, relies on fossil fuels, and results in significant carbon emissions. In contrast, electrochemical ammonia synthesis offers a promising alternative that can utilize renewable energy sources, thereby reducing environmental impact and enabling decentralized production. </sec><sec> Electrochemical ammonia synthesis is based on the principle of using electricity to drive chemical reactions to synthesize ammonia from hydrogen and nitrogen or nitrate. This method offers the potential for significant energy savings and carbon emission reductions compared to the Haber-Bosch process. In addition, it can be combined with technologies such as thermal and photovoltaic, thereby facilitating a more sustainable and flexible ammonia production infrastructure. However, the electrochemical ammonia synthesis approach faces significant challenges that hinder its practical application and industrialization. </sec><sec> One of the main difficulties in the electrochemical synthesis of ammonia is the inherent inertness of the nitrogen molecule, which requires considerable energy to break its strong triple bonds. This property of nitrogen makes the electrochemical reduction process complex and inefficient. In addition, the electrochemical reduction process suffers from many side reactions that compete with the desired ammonia synthesis reaction. These side reactions not only cause unnecessary energy loss, but also reduce the overall efficiency and yield of ammonia production. Currently, the relatively low ammonia production rates and Faraday efficiencies achieved through electrochemical ammonia synthesis make the process inadequate for large-scale industrial applications. Addressing these issues is critical to advancing electrochemical ammonia synthesis as a viable alternative to traditional ammonia synthesis methods. </sec><sec> This review focuses on the role of ionic liquids (IL) in improving the efficiency of electrochemical ammonia synthesis. ILs have unique properties that can be used to enhance the performance of electrochemical ammonia synthesis, including high ionic conductivity, low volatility, and high nitrogen solubility. This review explores how different types of ionic liquids can improve the efficiency of ammonia synthesis through three primary mechanisms. Firstly, IL can increase the solubility of nitrogen in solution, providing more nitrogen for the reduction reaction. Secondly, they can modulate the behavior of the catalyst in the electrolyte system, optimizing the reaction environment and increasing catalytic activity. Finally, by utilizing IL to adjust the internal environment of the electrolyte system, researchers can achieve more efficient nitrogen reduction and higher ammonia yields. </sec><sec> In addition, the review suggests future research directions to overcome the limitations of current electrochemical ammonia synthesis. These directions include developing functionalized IL to enhance nitrogen solubility, studying new catalyst materials that work in concert with IL, and optimizing the electrolyte to maximize ammonia productivity and efficiency. </sec><sec> In summary, while electrochemical ammonia synthesis offers a promising pathway toward sustainable and decentralized ammonia production, significant challenges remain. The application of IL provides a potential pathway to address these challenges and improve the efficiency of the electrochemical ammonia synthesis process. Continued research in this area is essential to realize the potential of electrochemical ammonia synthesis and contribute to the development of a greener and more sustainable hydrogen economy. </sec>