(384f) Direct Electrosynthesis of Ammonia from Nitrate Via Catalyst Design and Electrolyzer Engineering

Electrochemically converting nitrate ions, a widely distributed nitrogen source in industrial wastewater and polluted groundwater, into ammonia represents a sustainable route for both ammonia fuel synthesis and wastewater treatment. However, the reaction environments in current lab-scale tests are still far from practical conditions for generating ammonia from real wastewater. Here, we first report a high-performance Ru-dispersed Cu nanowire catalyst that delivers an industrial-relevant nitrate reduction current of 1 A cm–2 while maintaining a high NH3 Faradaic efficiency of 93%. This high nitrate-reduction catalytic activity enables over a 99% nitrate conversion into ammonia while still maintaining an over 90% Faradaic efficiency. Next, we design and fabricate a practical membrane electrode assembly (MEA) electrolyzer to perform nitrate reduction reaction. By transferring our catalyst into the MEA electrolyzer, we directly synthesis ammonia from the nitrate-containing influent without the need of additional salt or strong alkaline solution. Overall, we demonstrated an efficient and direct ammonia synthesis via both catalyst design and electrolyzer engineering.