Synergistic Electrocatalytic N2 Reduction over Asymmetric Heteronuclear Dual Ru-Fe Sites.

The scaling relationship limit poses a significant challenge in single-atom catalysts (SACs) for reactions involving multi-intermediate interactions, such as the electrocatalytic nitrogen reduction reaction (eNRR) for ammonia synthesis. To overcome this limitation, a heteronuclear dual Ru-Fe sites on N,S-codoped Ti3C2Tx nanosheet (referred to as Fe1-N^S-Ru1/Ti3C2Tx) with precisely designed asymmetric coordination for eNRR is developed. Advanced characterizations verify the unique asymmetric coordination structure where Ru and Fe atoms are individually coordinated to N and S atoms, respectively, with the two metal centers interconnected via bridging N and S atoms. This catalyst achieves remarkable eNRR performance with an NH3 yield rate of 32.8 µg h-1 mg-1 cat at -0.55 V and 47.1% Faradaic efficiency at -0.25 V, surpassing its homonuclear analogues by 3.2- and 2.3-fold in activity and ≈3.0-fold in selectivity. Experimental and theoretical studies reveal a synergistic mechanism, in which Ru sites effectively dissociate H2O to supply protons while the adjacent Fe sites selectively activate N2, effectively decoupling proton supply from N2 activation but also benefiting the formation of key intermediate *NNH. Additionally, the electronic interaction between Ru and Fe sites also lowers the energy barrier of the rate-determining step, thereby significantly enhancing catalytic activity and selectivity.