Stabilizing Cu+ species by Al-doping with enhanced *CO coverage for highly efficient electrochemical CO2 reduction to C2+ products†

Abstract

Copper-based oxide catalysts have garnered significant attention due to their remarkable capacity for selectively producing multicarbon (C₂₊) compounds in CO₂ reduction driven by renewable electricity. However, the Cu⁺ species in catalysts remain trapped in the self-reduction to Cu⁰ at the high applied reducing potentials. Herein, we report that Cu₃Al layered double hydroxides (Cu₃Al-LDHs) exhibit a remarkable electrochemical conversion of CO₂ to C₂₊, with a C₂₊ partial current density of 252 mA cm⁻² and a corresponding faradaic efficiency (FE) of 84.5%. In sharp contrast, the Cu₂(OH)₂CO₃ without Al (Cu-LDHs) showed an FE_C2+ of only 37.5% under the same conditions. In situ XRD measurements demonstrated that Cu₃Al-LDH underwent cathode reconstruction into Cu₂O, while Cu-LDHs transformed into metallic Cu during the CO₂RR process. In situ Raman spectroscopy indicated the introduction of Al facilitates the adsorption and dimerization of *CO. Density functional theory calculations revealed that the incorporation of Al effectively modulates the electronic structure of Cu and enhances the adsorption strength of *CO. Moreover, it exhibited a low energy barrier for the formation of *OCCO intermediates, thereby demonstrating remarkable selectivity towards C₂₊ products.