Unveiling Structure‐Activity Relationship With Structurally Defined and Stabilized Cu‐Based Molecular Hybrid Electrocatalysts in CO 2 Electroreduction

Deciphering the structure‐activity relationship on Cu‐based electrocatalysts is critical to rationally optimize their performances in CO 2 to multicarbon (C 2+ ) 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 CO 2 ‐C 2+ electrocatalysis, where a Ni(II) phthalocyanine anchored on Cu 2 O nanocubes via 2‐(3‐thienyl)ethoxy groups outperforms its Co(II) analog and unmodified prototype in C 2+ synthesis (78.3% selectivity, 330 mA . cm −2 ), rivaling top catalysts. Structural analysis revealed the functional 2‐(3‐thienyl)ethoxy anchors pose superior Cu 2 O 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 CO 2 ‐C 2+ conversion.