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 N-2 with the assistance of simultaneous electrochlorination, finally achieving 96.81% of N-2 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.