Synergistic FeGe dual sites in Fe₁₃Ge₈ Intermetallics boost nitrate reduction to Ammonia

The electrocatalytic nitrate reduction reaction (NO₃RR) provides a promising route for simultaneous nitrate (NO₃^-) removal and sustainable ammonia (NH₃) production. However, this process is limited by complex reaction pathways and sluggish kinetics. Herein, carbon-supported Fe₁₃Ge₈ intermetallic compounds (i.e. Fe₁₃Ge₈/C) are synthesized via a high-temperature annealing strategy. The obtained Fe₁₃Ge₈/C catalyst exhibits an NH₃ yield rate of 5.8 mg·h^-1·cm^-2 and a Faradaic efficiency (FE) of 93% at -0.7 V in 1.0 M potassium hydroxide (KOH), outperforming carbon-supported iron nanoparticles (i.e. Fe/C) and most of the reported noble-metal-free NO₃RR electrocatalysts. Density functional theory (DFT) calculations reveal that Fe sites in Fe₁₃Ge₈ effectively facilitate the adsorption and activation of NO₃^-. Meanwhile, Ge sites promote water (H₂O) dissociation and active hydrogen (*H) generation, thereby continuously supplying abundant *H for subsequent hydrogenation steps. The synergistic interaction between Fe and Ge dual sites in Fe₁₃Ge₈ significantly reduces the energy barrier of the rate-determining step in NO₃RR.