Zirui Liu, Jiacheng Jayden Wang, Yifan Li, Chenglong Qiu, Yunhong Liang, Jiacheng Wang
Electrocatalytic synthesis of ammonia (NH3) from nitrate (NO3-) is an effective approach for reducing nitrate pollutants in the environment and a promising method for ammonia synthesis under mild conditions. However, current catalyst synthesis is costly, and their application in real wastewater remains underexplored. Herein, we prepared high-efficiency copper-based single-atom-nanoparticle synergistic sites on carbon felt (CuSA/NP@C) from copper-containing wastewater. Trace Cu2+ in wastewater enables efficient nitrate reduction reaction (NO3RR), and the effect of different Cu2+ concentrations was also investigated. The optimized CuSA/NP@C, with synergy between single atoms and nanoparticles, shows excellent activity: maximum Faraday efficiency of ~100% (at -0.3 V vs. RHE) and NH3 yield of ~10 mg cm-2. Theoretical calculations reveal that Cu single-atoms and nanoparticles synergistically act on the NO3* and H* intermediates to promote nitrate hydrogenation to NH3. A membrane electrode assembly with the CuSA/NP@C cathode achieves NH3 synthesis at an industrial current density of 200 mA cm-2 for over 90 hours. This “treating waste with waste” strategy offers new paths for nitrate wastewater recycling and green NH3 synthesis advancement.