Tuning Asymmetric S-Bridged Cu─Co Dual Sites at Atomic-Level for Efficient Ammonia Electrosynthesis

Electrochemical nitrate reduction reaction (NO₃RR) for ammonia production holds immense promise as an environmentally benign strategy. Nevertheless, the process faces inherent limitations by sluggish kinetics of the eight-electron transfer and multiple competing reactions. Here, an asymmetric S-bridged Cu, Co dual-atom (Cu─S─Co) catalyst (CuCo-SNC) is creatively reported by leveraging the abundant disulfide bond capture and chelation capabilities of wool keratin. Benefiting from the charge regulation effect between the metal sites and S-bridged atoms, the CuCo-SNC catalyst exhibits an optimal Faradaic efficiency of 97.8% at −0.3 V (vs RHE) and a remarkable NH₃ yield rate of 0.88 mmol h⁻¹ cm⁻² at −0.6 V (vs RHE). The assembled Zn-NO₃⁻ battery shows a power density of 7.99 mW cm⁻² and exceptional cycling stability. Furthermore, in situ characterization and theoretical analysis reveal that the S-bridge breaks the electron balance between Cu and Co, effectively modulating the charge state of the Cu─Co site, which boosts electrons transfer from Cu to Co site through the S-bridge, thereby promoting the efficient conversion of nitrate ions (NO₃⁻) at Co─Cu bimetallic sites. This asymmetric dual atom catalyst provides a novel perspective for the development of advanced electrocatalytic technologies in ammonia synthesis.