Electrochemical nitrate-to-ammonia reduction over atomic Fe-dopants incorporated in CoS2

Electrochemical reduction of NO3− to NH3 (NO3RR) offers a promising way to mitigate harmful nitrate and produce valuable NH3 simultaneously. However, the sluggish NO3RR reaction kinetics and competitive H2 evolution reaction (HER) greatly limit NO3−-to-NH3 conversion efficiency. Herein, we discover that atomic Fe-dopants incorporated in CoS2 (Fe-CoS2) can effectively catalyze NO3RR in neutral solution, showing a maximum NH3-Faradaic efficiency of 97.5% with an NH3 yield rate of 10.8 mg h−1 cm−2 at −0.6 V vs. RHE, together with an excellent catalytic stability. The XAS characterizations validate an atomic-level dispersion of Fe-dopants in CoS2. Theoretical computations combined with in situ FITR/EPR spectroscopic analyses unravel that atomic Fe-dopants can accelerate the NO3RR hydrogenation process and restrict the competing HER, resulting in high NO3RR activity and selectivity of Fe-CoS2.