Unveiling Structure-Activity Relationship With Structurally Defined and Stabilized Cu-Based Molecular Hybrid Electrocatalysts in CO2 Electroreduction.

Deciphering the structure-activity relationship on Cu-based electrocatalysts is critical to rationally optimize their performances in CO2 to multicarbon (C2+) conversion, which nonetheless remains highly challenging due to their ill-defined and electrochemically unstable structures. Herein, this study explores Cu-based molecular hybrids with defined structures to establish structure-activity relationships in CO2-C2+ electrocatalysis, where a Ni(II) phthalocyanine anchored on Cu2O nanocubes via 2-(3-thienyl)ethoxy groups outperforms its Co(II) analog and unmodified prototype in C2+ synthesis (78.3% selectivity, 330 mA.cm-2), rivaling top catalysts. Structural analysis revealed the functional 2-(3-thienyl)ethoxy anchors pose superior Cu2O affinity to retain the Cu(I) structure and the grafted metal phthalocyanines during catalysis. Such stabilized and well-defined catalyst structures enable the structure-activity relationship unveiled by in situ spectroscopies and theoretical calculations. The results show that the synergy between the molecular metal centers and surface Cu atoms fine-tunes the energy barriers for both CO transfer and *OCCO hydrogenation, which are minimized by the optimal Cu-S-Ni coordination endowing abundant Cu(I)Cu(0)-paired active sites with an electron-rich Ni center. This work demonstrates the essential role of metal-ligand cooperativity in C-C coupling and successfully bridges mechanistic insights with catalyst design for efficient CO2-C2+ conversion.