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

Electrochemical nitrogen oxide ions reduction reaction (NOx−RR) shows great opportunity for ammonia production under ambient conditions. Yet, performing NOx−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 La1.5Sr0.5Ni0.5Fe0.5O4 perovskite oxide for the NOx−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 NOx−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 NH3 production rate at 20 A. This catalyst's unique acid‐operability streamlines downstream ammonia utilization for direct ammonium salt production and upstream integration with NOx sources. Techno‐economic and lifecycle assessments reveal substantial economic advantages for this ammonia production strategy, even when coupled with a plasma‐based NOx production system, presenting a sustainable complement to the conventional Haber‐Bosch process.