Fabrication of Ultrahigh‐Loading Dual Copper Sites in Nitrogen‐Doped Porous Carbons Boosting Electroreduction of CO₂ to C₂H₄ Under Neutral Conditions

Abstract Synthesis of high‐loading atomic‐level dispersed catalysts for highly efficient electrochemical CO₂ reduction reaction (eCO₂RR) to ethylene (C₂H₄) in neutral electrolyte remain challenging tasks. To address common aggregation issues, a host‐guest strategy is employed, by using a metal‐azolate framework (MAF‐4) with nanocages as the host and a dinuclear Cu(I) complex as the guest, to form precursors for pyrolysis into a series of nitrogen‐doped porous carbons (NPCs) with varying loadings of dual copper sites, namely NPC_MAF‐4‐Cu₂‐21 (21.2 wt%), NPC_MAF‐4‐Cu₂‐11 (10.6 wt%), and NPC_MAF‐4‐Cu₂‐7 (6.9 wt%). Interestingly, as the loading of dual copper sites increased from 6.9 to 21.2 wt%, the partial current density for eCO₂RR to yield C₂H₄ also gradually increased from 38.7 to 93.6 mA cm⁻². In a 0.1 m KHCO₃ electrolyte, at −1.4 V versus reversible hydrogen electrode (vs. RHE), NPC_MAF‐4‐Cu₂‐21 exhibits the excellent performance with a Faradaic efficiency of 52% and a current density of 180 mA cm⁻². Such performance can be attributed to the presence of ultrahigh‐loading dual copper sites, which promotes C─C coupling and the formation of C₂ products. The findings demonstrate the confinement effect of MAF‐4 with nanocages is conducive to the preparation of high‐loading atomic‐level catalysts.