Highly Stable Perovskite Oxides for Electrocatalytic Acidic NO_x⁻ 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_1.5Sr_0.5Ni_0.5Fe_0.5O₄ 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 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 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.