Promoted Electrochemical\nAmmonia Synthesis from Nitrate\nat the Ag–Cu Biphasic Interface

Electrochemical nitrate reduction (NO<sub>3</sub><sup>–</sup>R) presents a promising pathway for carbon-neutral\nammonia (NH<sub>3</sub>) synthesis. Enhancing NH<sub>3</sub> selectivity\nthrough\na tandem process can be achieved by combining Cu with a secondary\nmetal, which allows for an adjustable binding energy between the bimetallic\ncatalyst and key nitrogen intermediates. Herein, we developed a biphasic\nAg–Cu heterostructure with a controllable elemental composition,\nwhich significantly improved NH<sub>3</sub> production through tandem\nNO<sub>3</sub><sup>–</sup>R. In-situ infrared spectroscopy\nand finite element simulations revealed that Ag serves as the active\nsite for converting NO<sub>3</sub><sup>–</sup> to NO<sub>2</sub><sup>–</sup>, leading to a high localized concentration of\nNO<sub>2</sub><sup>–</sup>, which is subsequently reduced to\nNH<sub>3</sub> on adjacent Cu sites. Density functional theory calculations\nfurther confirmed the critical role of the Ag–Cu biphasic interface\nin promoting tandem NH<sub>3</sub> production. This work offers valuable\ninsights into the tandem NO<sub>3</sub><sup>–</sup>R pathway\nin bimetallic heterostructures, providing a foundation for optimizing\ncatalysts and advancing large-scale sustainable NH<sub>3</sub> synthesis.