Dual-Site Synergy of Ag/FeOOH Boosts Electrocatalytic Reduction of Nitrate

In nitrate electrochemical reduction reaction (NO3RR), competing side reactions like hydrogen evolution often lead to poor selectivity and subpar kinetics, limiting practical use. Herein, using iron oxyhydroxide nanoarrays grown on a titanium mesh as the substrate, silver nanoparticles were introduced onto the tips of the iron oxyhydroxide nanowires via electrochemical deposition, thereby forming an Ag/FeOOH heterojunction electrocatalyst. At −0.85 V, Ag/FeOOH demonstrates excellent performance, with 97.56% ammonium selectivity, 92.45% nitrate conversion rate, and an ammonium yield of 3.21 mg h−1 cm−2. Furthermore, the Zn-NO3− battery exhibited a power density of 1.28 mW cm−2. Ag/FeOOH’s structure enhances interfacial nitrate adsorption and reduces NO3RR energy barriers, accelerating reaction kinetics. It promotes NO3−-to-NO2− conversion via dual-site synergy, boosting NH4+ yield and advancing electrocatalyst design.