Sulfur Mediated Interfacial Proton-Directed Transfer Boosts Electrocatalytic Nitric Oxide Reduction to Ammonia over Dual-Site Catalysts.

Electrocatalytic nitric oxide reduction reaction (NORR) for ammonia (NH) synthesis represents a sustainable strategy that simultaneously realizes the nitrogen cycle and resource integration. The key issue hindering the NORR efficiency is accelerating proton (*H) transfer to facilitate NO hydrogenation while inhibiting the hydrogen evolution reaction (HER). Herein, we demonstrate an interface-engineered sulfur-mediated Cu@Co electrocatalyst (S-Cu@Co/C) that boosts NORR performance through dual modulation of electronic structure and proton transfer on active sites. A comprehensive program of experimental and theoretical calculations was employed to discover that sulfur incorporation induces electron redistribution in the Cu-Co interface, creating electron-rich sulfur and electron-deficient metals. This electronic configuration synergistically enhances NO adsorption on Cu sites and promotes water dissociation on Co sites. More critically, sulfur could direct the rapid transfer of *H from Co to Cu sites, thereby accelerating the NO hydrogenation and suppressing HER. Consequently, S-Cu@Co/C achieves an NH yield rate of 655.3 µmol h cm in a flow cell and a Faradaic efficiency of 92.4% in an H-cell. Remarkably, the catalyst could maintain continuous electrolysis tests and steady NH yield up to 100 h. This work provides innovative insights into the fabrication of efficient electrocatalysts via heteroatom-mediated interfacial engineering strategies.