A comprehensive review of critical factors affecting green ammonia synthesis by electrochemical process

Ammonia, such as ammonium sulfate and urea, is crucial for fertilizers and the chemical industry in reducing agents and refrigerants. Additionally, ammonia is a promising carbon-free fuel due to its safety and established transportation and storage methods. The Haber-Bosch process, the primary method for ammonia synthesis, is energy-intensive and emits significant greenhouse gases. This process involves the reaction of nitrogen and hydrogen over a catalyst at high temperatures and pressures. With global carbon reduction goals for 2050, renewable energy sources like wind and solar are gaining importance. Therefore, the electrochemical synthesis of 'green ammonia' using renewable energy is a vital research direction.

This article undertook a meticulous analysis of 1298 journal documents related to ammonia synthesis, sifting through them to identify 172 relevant articles. Key terms such as electrochemical, ammonia synthesis, catalyst, electrode, and green ammonia were meticulously identified using NVivo tools. The research delves into the intricacies of electrochemical nitrogen reduction reaction (eNRR) pathways, nitrogen and hydrogen sources, temperature conditions, catalysts, electrodes, and electrolytes. By conducting a comprehensive comparison of the energy consumption and carbon emissions of various green ammonia synthesis processes, the study aims to pinpoint the optimal parameters for mainstream green ammonia synthesis, thereby providing a robust reference for future developments.