Engineering Cu + /Cu 0 Interfaces With Lanthanum Doping for Efficient CO 2 ‐to‐C 2+ Conversion

Copper‐based catalysts offer promise for CO 2 ‐to‐C 2+ conversion but suffer from instability of Cu + species, which are active sites critical for enabling C−C coupling. In this work, we synthesized Lanthanum (La)‐doped Cu x O (La‐Cu x O) catalysts with varying La/Cu ratios to investigate how the interplay between doping‐induced electronic effects and grain boundary (GB)‐driven stabilization affects deep CO 2 reduction to C 2+ . Combined density functional theory calculations and in situ spectroscopic characterization reveal that the unique 4f orbital configuration and strong Lewis acidity facilitate charge transfer of La, stabilizing Cu + during CO 2 reduction reaction (CO 2 RR), while simultaneously inducing lattice distortion to increase GB density. This modulation preserves Cu + /Cu 0 interfaces while enhancing *CO dimerization kinetics. Furthermore, La doping boosts *CO coverage at GB‐rich regions and lowers the C−C coupling barrier. The optimized La‐Cu x O‐2 catalyst (La/Cu = 0.224) achieves a 45.2% C 2 H 4 Faradaic efficiency (FE) and 75.4% C 2+ FE at −0.8 V RHE , with partial current densities of 87.5 and 146.7 mA cm −2 , respectively, surpassing undoped Cu x O. Remarkably, it retains more than 90% initial activity after 24 h operation, demonstrating exceptional stability. This work provides a rational strategy for stabilizing Cu + and tailoring pathways via rare‐earth doping.