Electrochemical Nitrogen Reduction to Ammonia Under Ambient Conditions: Stakes and Challenges

Aqueous electrochemical nitrogen reduction (ENR) to ammonia (NH3) under ambient conditions is considered as an alternative to the energy-intensive Haber-Bosch process for ammonia production. Many metal, non-metal, carbon-based materials along with metal-chalcogenides, metal-nitrides have been explored for their ENR activity. The reported NH3 production through ENR is still in the micro-gram level and often falls in the range of NH3 and NOx contaminations from the surrounding. The quantification of NH3 at very low concentration possess enormous challenge in this field and thus many reported ENR electrocatalysts suffer from reproducibility issue. This review highlights in detail the challenges associated with ENR in aqueous medium and necessitates standardization of protocols to quantify the low concentration of NH3 free of false-positives. It concludes the prospects of electrochemical NH3 production through lithium-mediated N-2 reduction.