Boosting Electrochemical Nitrate Reduction at Low Concentrations Through Simultaneous Electronic States Regulation and Proton Provision

Abstract

AbstractElectrochemically converting nitrate (NO3−) into ammonia (NH3) has emerged as an alternative strategy for NH3 production and effluent treatment. Nevertheless, the electroreduction of dilute NO3− is still challenging due to the competitive adsorption between various aqueous species and NO3−, and unfavorable water dissociation providing *H. Herein, a new tandem strategy is proposed to boost the electrochemical nitrate reduction reaction (NO3RR) performance of Cu nanoparticles supported on single Fe atoms dispersed N‐doped carbon (Cu@Fe1‐NC) at dilute NO3− concentrations (≤100 ppm NO3−‐N). The optimized Cu@Fe1‐NC presents a FENH3 of 97.7% at −0.4 V versus RHE, and a significant NH3 yield of 1953.9 mmol h−1 gCu−1 at 100 ppm NO3−‐N, a record‐high activity for dilute NO3RR. The metal/carbon heterojunctions in Cu@Fe1‐NC enable a spontaneous electron transfer from Cu to carbon substrate, resulting in electron‐deficient Cu. As a result, the electron‐deficient Cu facilitates the adsorption of NO3− compared with the pristine Cu. The adjacent atomic Fe sites efficiently promote water dissociation, providing abundant *H for the hydrogenation of *NOx e at Cu sites. The synergistic effects between Cu and single Fe atom sites simultaneously decrease the energy barrier for NO3− adsorption and hydrogenation, thereby enhancing the overall activity of NO3− reduction.