Promoted Electrochemical Ammonia Synthesis from Nitrate at the Ag–Cu Biphasic Interface

Electrochemical nitrate reduction (NO3–R) presents a promising pathway for carbon-neutral ammonia (NH3) synthesis. Enhancing NH3 selectivity through a tandem process can be achieved by combining Cu with a secondary metal, which allows for an adjustable binding energy between the bimetallic catalyst and key nitrogen intermediates. Herein, we developed a biphasic Ag–Cu heterostructure with a controllable elemental composition, which significantly improved NH3 production through tandem NO3–R. In-situ infrared spectroscopy and finite element simulations revealed that Ag serves as the active site for converting NO3– to NO2–, leading to a high localized concentration of NO2–, which is subsequently reduced to NH3 on adjacent Cu sites. Density functional theory calculations further confirmed the critical role of the Ag–Cu biphasic interface in promoting tandem NH3 production. This work offers valuable insights into the tandem NO3–R pathway in bimetallic heterostructures, providing a foundation for optimizing catalysts and advancing large-scale sustainable NH3 synthesis.