(707h) Computational Insights into Lithium-Mediated Electrochemical Nitrogen Reduction Reaction for Sustainable Ammonia Production

Ammonia is a critical component in fertilizers and an ideal zero-carbon energy carrier, yet its industrial production via Haber-Bosch process consumes enormous fossil fuels and generates significant carbon dioxide emissions. To overcome these challenges, electrochemical nitrogen reduction reaction (NRR) of leveraging excess renewable electricity to drive this process offers a promising alternative. Ammonia electrosynthesis can be realized through either direct electrocatalytic reduction or lithium-mediated electroreduction. Major concerns of the direct electrocatalytic route are sluggish kinetics, poor faradaic efficiencies, or erroneous results arose from potential contamination by ammonia and other nitrogen compounds, while lithium-mediated nitrogen reduction reaction (Li-NRR) in nonaqueous electrolytes has been experimentally validated as a more feasible and reliable method for ammonia electrosynthesis. However, the fundamental chemistry of Li-NRR remains unclear. Here, we employ advanced computational methodologies, i.e., density functional theory (DFT), to elucidate reaction mechanisms of electrocatalytic Li-NRR. We interrogate the role of solid electrolyte interface and microenvironments in tuning catalytic activity and computationally characterize the catalyst active sites. Our computational mechanistic analysis indicates that nitrogen reduction will not proceed through the traditional nitrogen associative or dissociative pathways in direct electrocatalytic NRR on metallic surfaces. Our study provides insights into understanding fundamental chemistry of Li-NRR and improving ammonia electrosynthesis performance.