Electrochemically upcycling wastewater nitrogen such as nitrate (NO3 –) and nitrite (NO2 –) into an ammonia fertilizer is a promising yet challenging research topic in resource recovery and wastewater treatment. This study presents an electrified membrane made of a CuO@Cu foam and a polytetrafluoroethylene (PTFE) membrane for reducing NO3 – to ammonia (NH3) and upcycling NH3 into (NH4)2SO4, a liquid fertilizer for ready-use. A paired electrolysis process without external acid/base consumption was achieved under a partial current density of 63.8 ± 4.4 mA·cm–2 on the cathodic membrane, which removed 99.9% NO3 – in the feed (150 mM NO3 –) after a 5 h operation with an NH3 recovery rate of 99.5%. A recovery rate and energy consumption of 3100 ± 91 g-(NH4)2SO4·m–2·d–1 and 21.8 ± 3.8 kWh·kg–1-(NH4)2SO4, respectively, almost outcompete the industrial ammonia production cost in the Haber–Bosch process. Density functional theory (DFT) calculations unraveled that the in situ electrochemical conversion of Cu2+ into Cu1+ provides highly dynamic active species for NO3 – reduction to NH3. This electrified membrane process was demonstrated to achieve synergistic nitrate decontamination and nutrient recovery with durable catalytic activity and stability.

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