Manipulating the C─C Coupling Pathway via Switchable Dual-Ligand Mediation in Copper(I) Nanoclusters for Selective CO2 Electroreduction to Ethylene/Ethanol.

Atomically precise nanoclusters (Cu NCs) offer an unmatched view of how active-site chemistry steers CO2 electroreduction, yet fine control over competing C2 products remains elusive. Here we introduce a switchable dual-ligand strategy that decorates an identical Cu13H10 core with tailored thiolate (-SR) and phosphine (-PR3) ligands, creating three isostructural catalysts (NC1 to NC3) whose surface electronics diverge by design. A single-step change in electron-withdrawing ligand flips selectivity from C2H4 (Faradaic efficiency, FEC2H4 ≈ 33 %) to EtOH (FEEtOH ≈ 31 %) without sacrificing ≥ -0.2 A·cm-2 current density. In situ ATR-SEIRAS and DFT reveal that -SR ligands accelerate *COCHO → *CCO dehydration toward C2H4, whereas electron-withdrawing -PR3 ligands stabilize *COCH2O route to EtOH. These insights deliver a clear design rule: modulate Cuẟ+ sites through ligand induction to program C─C coupling pathways on demand.