Hydrogen bond interactions on a dual-core copper catalyst promote the activation of low-concentration CO2 and the generation of ethylene

Abstract

The electroreduction of low-concentration carbon dioxide to ethylene is highly attractive, as it enables the utilization of dilute CO₂ in flue gas while producing high-value-added chemicals. However, the inherent difficulty of activating CO₂ at low concentrations has limited both the catalytic activity and ethylene selectivity of existing copper-based electrocatalysts. In principle, precise regulation of the coordination microenvironment in copper-based complex catalysts could substantially lower the energy barriers associated with CO₂ activation and C–C coupling, thereby enhancing CO₂-to-C₂H₄ conversion; nevertheless, this strategy remains largely unexplored. Here, we perform theoretical calculations on CO₂-to-C₂H₄ conversion over binuclear copper coordination complexes, [Cu₂(OH)₂L₂]-X (L = 1,10-phenanthroline or 2,2′-bipyridine; X = external anion), featuring OH⁻ bridging ligands. We demonstrate that the oxygen atoms of the OH⁻ ligands surrounding the binuclear copper centers form hydrogen bonds with the hydrogen atom of the *COOH intermediate, significantly lowering the energy barrier for CO₂ activation. Moreover, the adjacent Cu⋯Cu sites effectively promote C–C coupling, facilitating ethylene formation. Electrochemical CO₂ reduction tests reveal that the [Cu₂(OH)₂L₂]-X complexes exhibit outstanding catalytic activity and C₂H₄ selectivity, achieving faradaic efficiencies of up to 62.5% and 58.8%, respectively. This work offers a new design paradigm for highly efficient copper-based complex catalysts for the electroreduction of CO₂ to multicarbon products.