NH3 synthesis from 1.0 vol% nitric oxide gas via direct electrocatalytic reduction

Abstract Ammonia is a promising zero-carbon energy carrier; however, its conventional production is energy-intensive and dependent on fossil fuels. The electrochemical reduction of nitric oxide offers a sustainable alternative for ammonia synthesis while simultaneously mitigating nitrogen oxide pollutants. In this study, a solid polymer electrolyte cell equipped with an anion-exchange membrane was employed to improve nitric oxide mass-transfer and suppress the competing hydrogen evolution reaction by establishing a localized alkaline environment. Using a copper catalyst supported on carbon, ammonia was successfully produced with a Faraday efficiency of 22%. The introduction of platinum as a secondary metal further enhanced the catalytic performance. Under continuous electrolysis at a current density of −50 mA cm−2, the bimetallic copper–platinum catalyst achieved an ammonia formation rate of 2.2 mg h−1 cm−2, a Faraday efficiency of 34%, and a nitric oxide-to-ammonia conversion of 23%. These results demonstrated an effective strategy for continuous ammonia electrosynthesis from dilute nitric oxide streams and suggested a promising approach for utilizing low-concentration nitrogen oxide sources.