(296b) Electrified Pathways to Ammonia at Ambient Conditions

Chemical synthesis is responsible for significant emissions of carbon dioxide worldwide. These emissions arise not only due to the energy requirements of chemical synthesis, but since hydrocarbon feedstocks can be overoxidized or used as hydrogen sources. Using renewable electricity to drive chemical synthesis may provide a route to overcoming these challenges, enabling synthetic routes which operate at benign conditions and utilize sustainable inputs. We are developing an electrosynthetic toolkit in which distributed feedstocks, including carbon dioxide, dinitrogen, water, and renewable electricity, can be converted into diverse fuels, chemicals, and materials.

In this presentation, we will share recent advances made in our laboratory on nitrogen fixation to synthesize ammonia at ambient conditions. Specifically, our lab is pursuing a lithium-mediated approach to ammonia synthesis and understood the reaction network that controls the reductive chemistry. The coupling of kinetics and transport has a significant influence on the rates of ammonia synthesis, providing a means to improve selectivity of nitrogen fixation. We have developed non-aqueous gas-diffusion electrodes which lead to high rates of ammonia synthesis at ambient conditions, overcoming transport limitations that would otherwise exist. Understanding of the solid electrolyte interphase through cryogenic transmission electron microscopy has provided unprecedented insight into the atomic structure of the reactive interphase. These findings will be discussed in the context of a broader range of electrosynthetic transformations which could lead to local and on-demand production of critical chemicals and materials.