Coupled Pdδ--Cuδ+ Dipole for Enhanced Aqueous Nitrate Valorization at Ultralow Potentials

Nitrate (NO3-) pollution poses significant threats to water quality and the global nitrogen cycle. The electrochemical NO3- reduction reaction (NO3RR) emerges as a promising solution for NO3- removal and sustainable ammonia (NH3) production. However, it suffers from an insufficient atomic hydrogen (*H) supply and poor nitrite (NO2-) adsorption at low potentials, which results in restrained NO3--to-NH3 conversion and notorious NO2- accumulation. Herein, we propose a dipole strategy that utilizes coupled divergent dual centers (Pdδ--Cuδ+) in binder-free monolithic single-atom alloy electrodes (Pd1Cu) to overcome these challenges at ultralow potentials. In-situ experiments and theoretical simulations reveal that the polarized atomic Pdδ- dramatically enhances *H supply by facilitating water dissociation into *H, which then readily spills over to the adsorption-strengthened NO2- on adjacent Cuδ+, thus promoting rapid deep hydrodeoxygenation at ultralow potentials. Furthermore, the upshifted d-band center inhibits *H self-coupling and reduces the thermodynamic energy barrier for the *NO intermediate hydrogenation. Leveraging these advantages, the coupled Pdδ--Cuδ+ dipole achieved 100% NO3- removal, 100% NH3 selectivity, near-zero NO2- accumulation, 94.4% NH3 Faradaic efficiency, and an NH3 yield rate of 1.98 mM h-1 cm-2 at just -0.2 V vs RHE, outperforming the monometallic counterparts and reported advanced catalysts. The proposed metal-dipole strategy can provide a universal principle for the rational design of electrocatalysts to valorize pollutants into valuable ammonia products.