“Molecular Tug‐of‐War” on Cu 0 ‐Fe δ+ Steps for N═O Bond Breaking with Active Hydrogen Feeding Toward Efficient NH 3 Electrosynthesis

ABSTRACT Copper (Cu) is among the most active monometallic catalysts for the electrosynthesis of ammonia (NH 3 ) from nitrite (NO 2 − ) and nitrate (NO 3 − ), yet its performance is fundamentally hampered by inefficient N═O bond cleavage and sluggish hydrogenation kinetics. In this work, these limitations are overcome by constructing a terraced Fe(OH) x /Cu heterostructure that features step‐like interfacial motifs consisting of Cu 0 and Fe δ+ sites. This unique architecture functions as a “molecular tug‐of‐war” catalyst while also enabling efficient active hydrogen (*H) supply. At these step‐edges, Cu 0 and Fe δ+ sites within a DFT‐supported model are proposed to operate synergistically to adsorb and activate *NO intermediate, where the N atom binds to Cu 0 and an O atom anchors on the Lewis acidic Fe δ+ , collectively straining the N═O bond and promoting its cleavage. Concurrently, the Fe δ+ enhances water dissociation to generate active hydrogen, thereby accelerating hydrogenation of nitrogen‐containing intermediates. This cooperative mechanism achieves a high Faradaic efficiency (FE) of 99.2% and an exceptional NH 3 production rate of 49.8 mg h −1 cm −2 . This work establishes a cooperative bond‐breaking and hydrogen‐feeding strategy as a novel paradigm for bifunctional catalyst design, offering new strategic insights into the catalytic valorization of nitrogenous wastes.