Strained Au skin on Mesoporous Intermetallic AuCu3 Nanocoral for Electrocatalytic Conversion of Nitrate to Ammonia across a Wide Concentration Range

Abstract Electrochemical nitrate reduction reaction (NitRR) uses nitrate from wastewater, offering a hopeful solution for environmental issues and ammonia production. Yet, varying nitrate levels in real wastewater greatly affect NitRR, slowing down its multi‐step process. Herein, a multi‐strategy approach was explored through the design of ordered mesoporous intermetallic AuCu 3 nanocorals with ultrathin Au skin ( meso ‐ i ‐AuCu 3 @ ultra ‐Au) as an efficient and concentration‐versatile catalyst for NitRR. The highly penetrated structure, coupled with the compressive stress exerted on the skin layer, not only facilitates rapid electron/mass transfer, but also effectively modulates the surface electronic structure, addressing the concentration‐dependent challenges encountered in practical NitRR process. As expected, the novel catalyst demonstrates outstanding NitRR activities and Faradaic efficiencies exceeding 95 % across a real and widespread concentration range (10–2000 mM). Notably, its performance at each concentration matched or exceeded that of the best‐known catalyst designed for that concentration. Multiple operando spectroscopies unveiled the catalyst concurrently optimized the adsorption behavior of different intermediates (adsorbed *NO x and *H) while expediting the hydrogenation steps, leading to an efficient overall reduction process. Moreover, the catalyst also displays promising potential for use in ammonia production at industrial‐relevant current densities and in conceptual zinc‐nitrate batteries, serving trifunctional nitrate conversion, ammonia synthesis and power supply.