Highly Stable Perovskite Oxides for Electrocatalytic Acidic NOx⁻ Reduction Streamlining Ammonia Synthesis from Air

Electrochemical nitrogen oxide ions reduction reaction (NO x − RR) shows great opportunity for ammonia production under ambient conditions. Yet, performing NO x − RR in strong acidic conditions remains challenging due to the corrosion effect on the catalyst and competing hydrogen evolution reactions. Here, we demonstrate a stable La 1.5 Sr 0.5 Ni 0.5 Fe 0.5 O 4 perovskite oxide for the NO x − RR at pH 0, achieving a Faradaic efficiency for ammonia of approaching 100 % at a current density of 2 A cm −2 in a H‐type cell. At industrially relevant current density, the NO x − RR system shows stable cell voltage and Faradaic efficiency for >350 h in membrane electrode assembly (MEA) at pH 0. By integrating the catalyst in a stacked MEA with a series connection, we have successfully obtained a record‐breaking 2.578 g h −1 NH 3 production rate at 20 A. This catalyst‘s unique acid‐operability streamlines downstream ammonia utilization for direct ammonium salt production and upstream integration with NO x sources. Techno‐economic and lifecycle assessments reveal substantial economic advantages for this ammonia production strategy, even when coupled with a plasma‐based NO x production system, presenting a sustainable complement to the conventional Haber–Bosch process.