Achieving efficient and stable electrochemical nitrate removal by in-situ reconstruction of Cu2O/Cu electroactive nanocatalysts on Cu foam

Efficient and stable electrocatalysts are essential for electrochemical denitrification of nitrate contamination in water. Herein, a cost-effective Cu2O/Cu NRs/CF cathode bearing abundant Cu active sites and electron-rich Cu2O sites with good atomic H* provision performance is reported to exhibit rapid nitrate reduction kinetics (0.04815 min−1) and no nitrite accumulation. Benefiting from the enhanced mass transfer and sufficient H* provision, the rapid adsorption of *NO3, fast reduction of *NO2 to *NO, and highly selective *NO to *NOH transformation played critical roles in the electrochemical nitrate reduction process. Although ammonia was the main final nitrate reduction product, the electrocatalytic system we designed could effectively oxidize ammonia into N2 with the assistance of simultaneous electrochlorination, finally achieving 96.81% of N2 selectivity. Significantly, the long-term stability and low energy consumption to treat actual nitrate-contaminated wastewater make the Cu2O/Cu NRs/CF electrode promising for practical applications.