Lutetium‐Mediated *OH Adsorption Tuning: Modulating *CH 2 CHO Transformation Pathways for Selective CO 2 Electroreduction to C 2 H 4 or CH 3 CH 2 OH

ABSTRACT Selective electroreduction of CO 2 into C 2 H 4 or C 2 H 5 OH is a high challenge. In this study, we achieved precise regulation of CO 2 RR selectivity by preparing lutetium‐doped CuO nanosheets (Lu/CuONS‐x) with varying Lu contents, where *OH adsorption behavior and intermediate dynamics are tailored by Lu doping. At 7% Lu doping, Lu atoms substitute Cu lattice sites, enhancing linear *OH (*OH L ) adsorption and strengthening the binding of the key intermediate for C 2 products formation. This induces a longer C−O bond in ⁎ CH 2 CH 2 O, facilitating C−O cleavage and achieving a C 2 H 4 Faradaic efficiency (FE) of 68.5% at −1.2 V vs. RHE in a flow cell device. In contrast, 15% Lu doping dominates bridged *OH (*OH B ) adsorption, driving the CH 2 CHO into the CH 3 CHO intermediate, yielding a C 2 H 5 OH FE of 52.2%. Density functional theory calculations confirm Lu doping upshifts the d‐band center of the catalyst, reduces C−C coupling energy barriers, and modulates formation energies of reaction intermediates. The formation energy of *CH 2 CH 2 O (−0.26 eV) is favored for C 2 H 4 generated on Lu/CuONS‐7%, while *CH 3 CHO (−1.28 eV) is preferred for C 2 H 5 OH generated on Lu/CuONS‐15%. Both catalysts effectively suppress H 2 evolution and maintain stable performance for 24 h, providing critical insights into tuning *OH adsorption for selective C 2 product synthesis.