N-O pair synergy in N2-Cu-O2 units for highly effective ethylene electroproduction

While copper complexes intrinsically provide Cu sites for electrocatalytic CO 2 reduction (ECR), their efficacy toward multicarbon products (C 2+ ) remains fundamentally limited by the operational instability of reactive Cu valence states and the inability to synchronously optimize *CO intermediate generation and C-C coupling within symmetric coordination environments. Herein, we judiciously design a single-crystal N, O co-coordinated copper complex (Cu(ICA) 2 ) featuring asymmetric N 2 -Cu-O 2 centers that precisely modulate the electronic structure and local adsorption environment. The Cu-N bonds stabilize partially reduced Cu δ⁺ sites while weakening Cu-O interactions, thus balancing structural integrity with catalytic reactivity. This asymmetric dual-site coordination concurrently hosts distinct *CO intermediates (atop-adsorbed *CO at Cu sites and bridge-adsorbed *CO at Cu-N sites), enabling cooperative C-C coupling into C 2 products. The catalyst achieves a record 69.2 % Faradaic efficiency for C 2 products at 400 mA cm −2 and 57.4 % for C 2 H 4 at 500 mA cm −2 in 1.0 M KOH, rivaling the state-of-the-art Cu-based complexes. In situ characterization and DFT calculations mechanistically corroborate that bridge-adsorbed *CO at Cu-N sites drives energetically favorable hydrogenation and C-C coupling pathways. This work establishes a coordination-asymmetry design principle for constructing robust molecular catalysts capable of efficient CO 2 -to-C 2+ conversion.