Efficient Electrochemical Nitrate Reduction to Ammonia on Novel Catalyst Ruthenium-Dispersed Copper Nanowires

The Haber-Bosch process currently dominates global ammonia production while consisting of 2% of global energy use and 1.4% of carbon dioxide emissions. Electrochemically converting nitrate ions, a widely distributed nitrogen source in industrial wastewater and polluted groundwater, into ammonia represents a sustainable route for both wastewater treatment and ammonia generation. However, this electrochemical reduction process is currently hindered by low catalytic activities, especially under low nitrate concentrations. This poster reports a high-performance ruthenium dispersed copper nanowire catalyst that delivers an industrially relevant nitrate reduction current of 1 A cm² while maintaining a high NH₃ Faradaic efficiency of 93%. More importantly, this high nitrate reduction catalytic activity enables over a 99% nitrate conversion into ammonia, converting from an industrial wastewater level of 2,000 ppm NO₃ to a drinkable water level <50 ppm NO₃, while still maintaining an over 90% Faradaic efficiency. Coupling the nitrate reduction effluent stream with an air stripping process, we can obtain high purity solid NH₄Cl and liquid NH₃ solution products, which suggests a practical approach to convert wastewater nitrate into valuable ammonia products. Density functional theory calculations reveal that the highly dispersed Ru atoms provide active nitrate reduction sites and the surrounding Cu sites can suppress the main side reaction, the hydrogen evolution reaction.