Bicarbonate‐Stabilized Cu ₂ O/Cu Heterointerfaces Enable Efficient Ethylene Electrosynthesis From Carbon Capture Solutions

Abstract The direct electrochemical conversion of carbon capture solutions into multi‐carbon (C ₂₊ ) products offers a sustainable alternative to decarbonize chemical manufacturing, bypassing energy‐intensive CO ₂ regeneration and purification steps in conventional CO ₂ conversion technologies. However, it faces persistent challenges in selectivity and operational stability. Here, this study demonstrates that bicarbonate, an inherent component of carbon capture media, stabilizes Cu ₂ O/Cu heterointerfaces in laminate oxide‐derived Cu (LOD‐Cu) catalysts, enabling long‐term ethylene (C ₂ H ₄ ) production. In a zero‐gap membrane electrode assembly (MEA) electrolyzer, bicarbonate electrolytes support a C ₂ H ₄ Faradaic efficiency of ≈54% at 200 mA cm ⁻² over 80 h of continuous operation. In situ spectroscopic analysis reveals that bicarbonate mitigates the full reduction of Cu ₂ O, preserving interfacial motifs that are critical for C─C coupling. This work uncovers bicarbonate's role in stabilizing Cu ₂ O/Cu heterointerfaces, thereby preserving catalytically active motifs and enabling efficient, durable C ₂ H ₄ production. It provides a practical strategy for integrating carbon capture with renewable C ₂ H ₄ chemical synthesis.