Dual‐Orbital Synergy and Alkali Metal Modulation: Harnessing Cu–Gd d – f Coupling for Enhanced CO 2 Reduction with Regulated Hydrogenation Selectivity

Abstract The rational design of Cu‐based catalysts with tailored electronic structures and optimized reaction pathways is critical for achieving efficient CO 2 ‐to‐multicarbon conversion. Here, a dual‐orbital synergy and alkali metal modulation strategy is reported by constructing Ba/Gd‐Cu 2 O polyhedrons. The optimized catalyst achieves a remarkable C 2 Faradaic efficiency (FE) of 78.6% with a partial current density of 402.3 mA cm −2 at −1.20 V versus RHE in a flow cell, demonstrating exceptional ethanol selectivity (48.2% FE) and stability over 30 h. The in situ spectroscopic studies and theoretical analysis reveal that Gd doping reshapes the Cu d ‐band electronic structure, lowering the energy barrier for * CO‐ * COH coupling through d – f orbital hybridization, while Ba atoms suppress local proton concentration to favor * OCCOH and * OC 2 H 5 stabilization and ethanol pathway progression. This work provides a dual‐functional design principle for synergistically enhancing C─C coupling kinetics and product selectivity in CO 2 electrolysis.