Constructing Asymmetric Sn-Cu-C Interface via Defective Carbon Trapped Atomic Clusters for Efficient Neutral Nitrate Reduction.

Abstract

Multi-atom cluster (MACs) catalysts have recently attracted significant research interest for their potential to catalyze multi-electron reactions through cooperative interactions among adjacent active sites. However, the controllable synthesis of MACs and the electrocatalytic mechanism understanding of their synergistic effects remain challenging. Herein, we develop a defect engineering strategy to anchor bimetallic SnCu atomic clusters at defective graphene (SnCu-DG) via carbon defect-mediated atomic trapping, wherein edge defects act as confined reactors for cluster nucleation. Taking nitrate reduction as an example, the SnCu-DG catalyst achieves a high NH₃ Faradaic efficiency (99.5%) at neutral electrolyte condition, accompanied by a record intrinsic activity of 2.61 × 10^-17 mmol h^-1 site_Cu ^-1, surpassing Cu-DG and SnCu-G counterparts by 16.0- and 7.8-fold, respectively. X-ray adsorption spectra and theoretical calculations reveal the electrons transfer between Cu and carbon defect sites while Sn incorporation intensifies asymmetric charge polarization across the Sn-Cu-C interface. This dual modulation collaboratively optimizes the catalytic microenvironment, simultaneously enhancing *NO₂ ^- adsorption, accelerating water dissociation kinetics, and breaking the intrinsic linear scaling between intermediate adsorption and hydrogenation.