Cu 1 -Fe Dual Sites for Superior Neutral Ammonia Electrosynthesis from Nitrate.

The electrochemical nitrate reduction reaction (NO 3 RR) is able to convert nitrate (NO 3 - ) into reusable ammonia (NH 3 ), offering a green treatment and resource utilization strategy of nitrate wastewater and ammonia synthesis. The conversion of NO 3 - to NH 3 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 3 from NO 3 - . Herein, we constructed a Cu 1 -Fe dual-site catalyst by anchoring Cu single atoms on amorphous iron oxide shell of nanoscale zero-valent iron (nZVI) for the electrochemical NO 3 RR, achieving an impressive NO 3 - removal efficiency of 94.8 % and NH 3 selectivity of 99.2 % under neutral pH and nitrate concentration of 50 mg L -1 NO 3 - -N conditions, greatly surpassing the performance of nZVI counterpart. This superior performance can be attributed to the synergistic effect of enhanced NO 3 - 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 3 from NO 3 - , and presents an environmentally sustainable approach for neutral nitrate wastewater treatment.