Electrochemical Ammonia Synthesis
Ammonia is a valuable product which is important for fertilizer production. It is also a liquid near atmospheric pressure, and thus is a promising carbon-free fuel. The direct electrochemical synthesis of ammonia from water and nitrogen is a major challenge because it suffers from strong kinetic competition from hydrogen evolution. Conn Center research in this area is focused on novel approaches to increase the selectivity for ammonia in the electrochemical nitrogen reduction reaction.
Carbon neutral liquid fuels are a highly desirable product for storing intermittent renewable electricity such as wind and solar. Their high volumetric energy density makes them promising for intensive portable energy applications such as transportation. Hydrocarbon synthesis from CO2 requires either an industrial feedstock from continued usage of fossil fuels, or an impractical reliance on the highly dilute (~400 ppm) CO2 concentration in the air. Ammonia, NH3, however, is carbon-free and liquid at relatively low pressure and temperature, and can be synthesized directly from N2 which makes up the majority of the atmosphere. Ammonia also is of major agricultural importance for producing fertilizer. Electrochemical synthesis of NH3 from N2 and H2O, however, has thus far been hindered by low selectivity due to the challenge of breaking the nitrogen triple bond at rates that are competitive with hydrogen evolution. Conn Center research in this area is exploring the effects of incorporating a nitrogen plasma in an electrochemical process to promote the formation of NH3.