Lateral Coordination Sulfur-Modified Charge Asymmetry Cu–Ru Diatomic Catalyst for Efficient and Stable Electrochemical Nitrate Reduction to Ammonia

Double-atom catalysts (DACs) with asymmetric coordination are crucial for enhancing the benefits of electrochemical reduction of nitrate (NO₃^–) to ammonia (NH₃) and advancing sustainable development; however, the rational design of DACs is still challenging. In this study, we synthesized atomically dispersed catalysts with lateral coordination sulfur-modified Cu–Ru sites (named N₂S₁Cu-RuN₃/SNC). The abundant defects and low-electronegativity heteroatoms in the carbon-based framework endow the asymmetric local structure of N₂S₁Cu-RuN₃at the atomic level, which is confirmed by aberration-corrected electron microscopy and X-ray absorption spectroscopy (XAS). In electrocatalytic nitrate reduction, the N₂S₁Cu-RuN₃/SNC shows a Faraday efficiency of 98.2% at −0.6 V versus reversible hydrogen electrode (RHE). Benefiting from the charge tuning effect between the metal site and the lateral coordination sulfur atoms, the ammonia yield reaches 0.02919 mmol cm^–2h^–1. Additionally, in situ XAS and density functional theory (DFT) calculations reveal that Cu–Ru active sites in the asymmetric N₂S₁Cu-RuN₃/SNC structure exhibit synergistic effects, modulating the adsorption of intermediates, lowering the energy barrier of key reaction steps, and enhancing the selectivity and yield of ammonia. This asymmetric bimetallic atomic catalyst facilitates deeper exploration of the precise synthesis and property modulation of atomic-scale materials.