Oxygen‐Bridge‐Mediated NiO/WO ₃ Heterostructure for Highly Efficient Electrocatalytic Nitrate‐to‐Ammonia Conversion

ABSTRACT Electrocatalytic NO 3 − ‐to‐NH 3 conversion offers a sustainable route for NH 3 production, yet its efficiency and selectivity are limited by the requirements of strong NO 3 − adsorption, efficient intermediates hydrogenation, and suppressed hydrogen evolution reaction (HER). Tungsten‐based oxides strongly adsorb NO x intermediates but show poor hydrogenation capability, whereas Ni‐based oxides efficiently dissociate H 2 O to promote hydrogenation yet often induce excessive HER. Herein, we construct an oxygen‐bridged NiO/WO 3 heterostructure to reconcile these functions via interfacial electronic modulation. Spectroscopic analyses reveal pronounced electron transfer across the W–O–Ni interface, generating electron‐enriched W(VI) and electron‐deficient Ni(II) species. These dual active sites optimize NO x adsorption on W sites while regulating proton availability at Ni sites, enabling stepwise hydrogenation with suppressed HER. The NiO/WO 3 heterostructure achieves Faradaic efficiency of 96.1 ± 3.4% and NH 3 yield rate of 9.2 mg h −1 cm −2 at −0.5 V vs. RHE, outperforming individual WO 3 and NiO. In‐situ infrared spectroscopy confirms moderated NO x adsorption‐desorption and weakened hydrogen adsorption, while density functional theory calculations confirms that oxygen‐bridged interfacial bonding optimizes NO x binding and attenuates HER. Furthermore, a NiO/WO 3 ‐based Zn–NO 3 − battery delivers a power density of 27.1 mW cm −2 . This work establishes an oxygen‐bridge‐mediated heterostructures enable precise dual‐site electronic regulation for selective NO 3 − ‐to‐NH 3 electrocatalysis.