Efficient Electrochemical Conversion of Nitric Oxide to Ammonia Using a Porous Nickel Catalyst in a Membrane Electrode Assembly Electrolyzer

The electrochemical synthesis of ammonia presents a promising pathway to decarbonize and electrify the production of the world’s second-largest commodity chemical. Among potential reactants, NOx gases stand out due to their favorable thermodynamics, advantageous kinetics, and availability from both combustion emissions and nitrogen-fixation processes, such as plasma-induced atmospheric nitrogen oxidation. However, the typically low concentrations of NOx in these sources poses significant challenges for electrochemical performance, particularly due to limitations in reactant mass transport. In this work, we report on the use of a porous nickel catalyst in a membrane electrode assembly (MEA) electrolyzer to enable the direct use of a dilute nitric oxide (NO) feed. The rational optimization of reactant mass transport enabled achieving a NO-to-NH3 single pass conversion of 93%, a faradaic efficiency for ammonia of 92% and an ammonium production rate of 557 μmol/h·cm2.