Cu-Fe Dual Sites for Superior Neutral Ammonia Electrosynthesis from Nitrate.

The electrochemical nitrate reduction reaction (NORR) is able to convert nitrate (NO ) into reusable ammonia (NH), offering a green treatment and resource utilization strategy of nitrate wastewater and ammonia synthesis. The conversion of NO to NH undergoes water dissociation to generate active hydrogen atoms and nitrogen-containing intermediates hydrogenation tandemly. The two relay processes compete for the same active sites, especially under pH-neutral condition, resulting in the suboptimal efficiency and selectivity in the electrosynthesis of NH from NO . Herein, we constructed a Cu-Fe dual-site catalyst by anchoring Cu single atoms on amorphous iron oxide shell of nanoscale zero-valent iron (nZVI) for the electrochemical NORR, achieving an impressive NO removal efficiency of 94.8 % and NH selectivity of 99.2 % under neutral pH and nitrate concentration of 50 mg L NO -N conditions, greatly surpassing the performance of nZVI counterpart. This superior performance can be attributed to the synergistic effect of enhanced NO adsorption on Fe sites and strengthened water activation on single-atom Cu sites, decreasing the energy barrier for the rate-determining step of *NO-to-*NOH. This work develops a novel strategy of fabricating dual-site catalysts to enhance the electrosynthesis of NH from NO , and presents an environmentally sustainable approach for neutral nitrate wastewater treatment.