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 NPCMAF‐4‐Cu2‐21 (21.2 wt%), NPCMAF‐4‐Cu2‐11 (10.6 wt%), and NPCMAF‐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), NPCMAF‐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.