Highly Selective Electrocatalytic Ammonia Synthesis Enabled by Spatial Separation of Active Hydrogen Capture and Spillover Sites

ABSTRACT Electrochemical nitrate reduction (eNO 3 RR) enables sustainable ammonia (NH 3 ) synthesis and nitrate (NO 3 − ) remediation but is limited by sluggish multi‐step proton−electron transfers and inefficient intermediate conversion. To address these challenges, we strategically manage the generation and utilization of active hydrogen (H * ) by integrating metallic Cu with atomically dispersed Zn−N 4 sites, thereby selectively increasing NH 3 production. In situ x‐ray absorption spectroscopy, in situ infrared, in situ Raman, and combined with theoretical calculations, systematically demonstrate that Zn−N 4 sites facilitate water dissociation to generate and capture H * species. These H * species subsequently spill over to neighboring metallic Cu, which play a crucial role in NO 3 − adsorption and activation. The spatial separation effect between H * capture and utilization sites ensures continuous H * generation and supply, thus enhancing N─H bond coupling for efficient NH 3 synthesis. As a result, the catalyst achieves a maximum NH 3 yield rate of 21.96 mg h −1 cm −2 and a highest Faradaic efficiency (FE) of 97.07% in 0.1 M KNO 3 under alkaline media. The constructed Zn‐NO 3 − battery can deliver an impressive power density of 14.59 mW cm −2 , a NH 3 yield rate of 4.26 mg h −1 cm −2 , and a FE of 93.65%, while consistently operating for over 100 h.