Electrosynthesis of ammonia with high selectivity and high rates via engineering of the solid-electrolyte interphase.

Ammonia is a large-scale commodity essential to fertilizer production, but the Haber-Bosch process leads to massive emissions of carbon dioxide. Electrochemical ammonia synthesis is an attractive alternative pathway, but the process is still limited by low ammonia production rate and faradaic efficiency. Herein, guided by our theoretical model, we present a highly efficient lithium-mediated process enabled by using different lithium salts, leading to the formation of a uniform solid-electrolyte interphase (SEI) layer on a porous copper electrode.

Enhancement of lithium-mediated ammonia synthesis by addition of oxygen.

Owing to the worrying increase in carbon dioxide concentrations in the atmosphere, there is a need to electrify fossil-fuel–powered chemical processes such as the Haber-Bosch ammonia synthesis. Lithium-mediated electrochemical nitrogen reduction has shown preliminary promise but still lacks sufficient faradaic efficiency and ammonia formation rate to be industrially relevant. Here, we show that oxygen, previously believed to hinder the reaction, actually greatly improves the faradaic efficiency and stability of the lithium-mediated nitrogen reduction when added to the reaction atmosphere in small amounts.