Spatial Confinement Enhancement and Orbital Modification of Copper-Aluminum Alloy Encapsulated within Carbon Nanofibers for Ampere-Level Carbon Dioxide Reduction Reaction

Electrochemically converting carbon dioxide (CO 2 ) into valuable multicarbon products by electrocatalysis, such as ethylene and ethanol, has drawn attention recently because it can decrease CO 2 in the atmosphere effectively and create economic value. Copper is the only catalyst capable of producing multicarbon products but still shows poor selectivity under a high current density. To resolve this problem, in this study, we developed a copper-aluminum alloy enclosed inside the carbon nanofiber. Carbon nanofibers with a larger diameter provide good carbon dioxide permeability, conductivity, and a well-defined spatial confined environment, concentrating CO * intermediates. Copper-aluminum alloy can regulate the 3d orbitals of the active sites, enhancing the overall catalytic activity. X-ray absorption spectroscopy and resonant inelastic X-ray scattering enable us to observe the alteration in 3d orbitals of copper by aluminum, confirming aluminum changing the electronic structure and improving the copper for carbon dioxide reduction reactions. Our developed electrocatalyst achieves the Faradaic efficiency of 73.05% toward C 2+ products under the operating current density of 1200 mA/cm2 and the partial current density of 876.6 mA/cm 2 . It overperforms the pristine copper, whose C 2+ Faradaic efficiency is 70.29% under the operating current density of 200 mA/cm 2 and the partial current density of 140.58 mA/cm 2 . We hope our results can provide insightful information for industrial development of carbon dioxide reduction reaction, aiming to reduce carbon dioxide emissions and contribute to the well-being of our planet. Figure 1