Tailoring surface charge distribution via lattice Cl-doping on Cu₂O nanocubes for high-selectivity CO₂-to-C₂₊ electroreduction via asymmetric C–C coupling

Despite utilization of state-of-the-art Cu-based catalysts, achieving high selectivity and stability in multicarbon (C2₊) compounds production through electrocatalytic CO₂ reduction reaction (CO₂RR) remains a critical and challenging objective. Here we employ lattice chlorine-doped Cu₂O nanocubes (Cl_d-Cu₂O NCs) with well-defined {100} facets as a model catalyst to demonstrate that halogen doping can serve as a versatile and effective strategy for modulating surface charge distribution, thereby enhancing asymmetric C−C coupling toward high-selectivity C₂₊ products in CO₂RR. Compared to Cl-free Cu₂O NC_s, Cl_d-Cu₂O NCs exhibit a greatly enhanced C₂₊ Faraday efficiency, i.e., ~85% at −1.1 V (versus the reversible hydrogen electrode). Additionally, the Cl_d-Cu₂O NCs demonstrate significantly enhanced long-term durability, attributed to better preservation of the cubic morphology and more stable Cu^δ+ states. In-situ electrochemical studies reveal that Cl_d-Cu₂O NCs facilitate the formation of the key asymmetric *COH and *OCCOH intermediates, ultimately leading to higher C₂₊ products. Density functional theory (DFT) calculations confirm that the introduced Cl-dopants disrupt the charge balance of the Cu₂O(100) surface, enriching the Cl-adjacent Cu atoms with more electrons compared to those near O atoms. This unbalanced charge distribution significantly reduces the free energy of the rate-determining step for asymmetric C−C coupling from the *CO to *OCCOH on Cl-doped Cu₂O(100) surface, requiring only 1.04 eV, in contrast to 1.50 eV on pristine Cu₂O(100) surface. This study provides valuable insights into the surface charge modulation of Cu₂O catalysts via halogen doping for enhancing asymmetric C−C coupling and C₂₊ production in CO₂RR. © Science China Press and Springer-Verlag Berlin Heidelberg 2025