Interfacial Tailoring of Graphene-Cu Heterostructure Boosts CO₂ Electroreduction Toward Ethylene

Electrochemical CO₂ reduction to multicarbon (C₂₊) products remains limited by sluggish CO₂ activation, inefficient C─C coupling, and competition from the hydrogen evolution reaction. Herein, we report a graphene-copper heterostructure catalyst (Gr@Cu) that significantly enhances ethylene production through rational interfacial electronic modulation. The optimized Gr@Cu_0.8 catalyst achieved a Faradaic efficiency of ~55% for ethylene (C₂H₄) at -0.87 V versus RHE. Density functional theory calculations reveal that interfacial charge transfer at the Gr@Cu interface lowers the energy barriers for both the CO₂ activation and *CO dimerization, thus promoting the key C─C coupling step. Frontier orbital and d-band center analyses further demonstrate that the heterostructure elevates the Cu d-band center and improves orbital coupling with reaction intermediates, facilitating electron transfer and intermediate adsorption. This work elucidates the structure-activity relationship of graphene-metal heterointerfaces and provides mechanistic guidelines for designing advanced electrocatalysts toward efficient and selective CO₂-to-C₂₊ conversion.