Large Dipole Moment Enhanced CO2 Adsorption on Copper Surface: Achieving 68.9% Catalytic Ethylene Faradaic Efficiency at 1.0 A cm−2

Abstract

The electrochemical conversion of carbon dioxide (CO₂) into hydrocarbon products emerges as a pivotal sustainable strategy for carbon utilization. Cu-based catalysts are currently prioritized as the most effective means for this process, yet it remains a long-term goal to achieve high product selectivity at elevated current densities. This study delved into exploring the influence of a topological poly(2-aminoazulene) with a substantial dipole moment on modulating the Cu surface dipole field to augment the catalytic activity involved in CO₂ reduction. The resulting Cu/poly(2-aminoazulene) heterojunction showcases a remarkable ethylene Faradaic efficiency of 68.9% even at a substantial current density of 1 A cm⁻². Through in situ Raman and in situ Fourier-transform infrared spectroscopy, poly(2-aminoazulene)-modified Cu electrode exhibits a heightened concentration of intermediates as compared to the bare Cu, proving advantageous for C−C dimerization. Theoretical calculations demonstrate the reduced energy barrier for C−C dimerization, and meanwhile impeding hydrogen evolution reaction on Cu/poly(2-aminoazulene) heterojunction, which are beneficial to CO₂ reduction. The catalyst design in this study, incorporating dipole moment considerations, not only investigates the influence of dipole moment on electrochemical carbon dioxide reduction but also pioneers an innovative strategy to augment catalytic activity by elevating the micro-concentration of reactants on catalyst surfaces.