Lateral Asymmetric Fe-Mn Dual-Atomic Sites for Efficient Nitrate Reduction^†

The development of efficient electrocatalysts for the reduction of nitrate (NO₃^-) to ammonia (NH₃) offers a sustainable alternative to the energy-intensive Haber–Bosch process, positioning this approach as a key focus in low-carbon and environmental research. However, practical implementation of the nitrate reduction reaction (NO₃^-RR) remains challenging due to the complexity of proton-coupled electron transfer and the sluggish kinetics arising from diverse reaction intermediates. In this work, we present an asymmetric Fe/Mn diatomic catalyst anchored on a metal–organic framework (MOF)-derived carbon skeleton, which exhibits outstanding catalytic performance for NH₃ synthesis, achieving a Faradaic efficiency of 98.7% at −0.4 V vs. RHE. Through combined in situ X-ray absorption spectroscopy (XAS) and density functional theory (DFT) calculations, we reveal that in the asymmetric Fe-Mn/SNC structure, strong electronic coupling between Fe and Mn active sites, together with synergistic modulation by S and N atoms, effectively optimizes the electronic structure, enhances structural stability, and ensures optimal atomic dispersion. The proposed transverse coordination-asymmetric heteronuclear diatomic cooperation mechanism provides a novel design strategy for advancing nitrate reduction and electrocatalytic ammonia synthesis.