Beyond catalyst design for the electrochemical nitrogen reduction reaction: The crucial role of water availability in the electrolyte composition

The electrochemical nitrogen reduction reaction (eNRR) has attracted attention in recent decades due to its potential for ammonia (NH₃) synthesis at mild conditions. This approach offers advantages over the traditional Haber-Bosch process, particularly in terms of mitigating its environmental drawbacks. However, the values achieved for Faradaic efficiency and ammonia yield rates are still far from desirable. Most reports in the literature have tested several different catalysts in aqueous electrolytes, where water acts both as a solvent and a proton source. However, this approach has disadvantages, as in aqueous electrolytes, parasitic reactions such as the hydrogen evolution reaction (HER) can compete with eNRR. Thus, in this review, we summarize the crucial role of the water availability in the electrolyte composition during the electrochemical nitrogen reduction reaction and how it can affect the catalyst performance.