Coupling of Nitrate Electroreduction to Ammonia with Sulfide Electrooxidation to Sulfur for High‐Efficiency Wastewater Treatment and Resource Recovery

Abstract Electrochemical nitrate reduction to ammonia (NO 3 RR) offers a sustainable alternative to conventional ammonia synthesis. However, its practical efficiency is hindered by the high energy consumption associated with the sluggish anodic oxygen evolution reaction (OER). Replacing OER with favorable sulfide oxidation reaction (SOR) significantly lowers cell voltage while converting nitrate and sulfide pollutants into valuable ammonia and sulfur. In this study, amorphous NiP x and CoS x catalysts are electrodeposited on nickel foam (NF) as high‐performance cathode and anode, respectively. The NiP x /NF cathode achieves an impressive NH 3 yield rate of 0.332 mmol h −1 cm −2 with 95.4% Faradaic efficiency (FE) at −0.2 V versus RHE, while the CoS x /NF anode demonstrates a low SOR overpotential of 0.376 V versus RHE at 100 mA cm −2 . The coupled NO 3 RR || SOR system demonstrates a 1.538 V reduction in cell voltage at 10 mA cm −2 compared to a conventional NO 3 RR || OER system, resulting in a 73% reduction in energy consumption for ammonia production. This work not only provides guidance for rationally designing high‐performance NO 3 RR and SOR electrocatalysts, but also paves an efficient route for simultaneous nitrate/sulfide wastewater treatment and resource recovery, demonstrating great application potential.