High‐Yield Ammonia Production from Al‐Nitrate Battery via Anodic Al&NO 3 − Spontaneous Reaction Driven Cathodic Nitrate Reduction Reaction

Abstract The electrocatalytic nitrate reduction reaction (NIRR) offers a sustainable alternative for ammonia (NH 3 ) synthesis, addressing the limitations of the energy‐intensive Haber‐Bosch process. This study introduces a novel aluminum‐nitrate (Al‐NO 3 − ) battery system that integrates anodic Al and NO 3 − (Al&NO 3 − ) spontaneous reactions with cathodic NO 3 − reduction, enabling simultaneous NH 3 production and electricity generation. The CuNi alloy films, synthesized via pulse laser confined bombardment (PLCB) technology, serve as efficient NIRR cathodes with tandem catalytic sites, delivering an NH 3 production rate of ≈58.04 mg h −1 cm −2 with a Faradaic efficiency (FE) of 99.40% at −1.3 V vs. Hg/HgO. The Al‐NO 3 − battery system, incorporating NO 3 − in both anodic and cathodic electrolytes, suppresses hydrogen evolution at the anode, and achieves an apparent FE exceeding 100% due to NO 3 − consumption for NH 3 production through both cathodic NIRR and the spontaneous anodic Al&NO 3 − reaction. Extended stability studies indicated continuous operation exceeding 50 h, with peak apparent FE reaching ≈183.60%. This system demonstrates a high NH 3 yield of over 10.0 mg h −1 cm −2 at a current density of 40 mA cm −2 . The findings highlight the potential of Al&NO 3 − spontaneous reactions to drive cathodic NO 3 − reduction, offering a sustainable pathway for NH 3 synthesis from NO 3 − ‐rich wastewater while generating electrical energy.