Ligand-Modulated Cu Reconstruction to Steer the Hydride/Hydroxyl Pathway of Electrocatalytic CO2 Reduction

Reconstructing metal-organic complexes effectively generates hybrid nanocatalysts for electrocatalytic CO2 reduction (eCO2R), but the role of metal-ligand interactions in shaping these hybrids and their influence on the electronic states of the reduced Cu species remain unclear. Herein, we impregnate Cu(II) acetate (Cu(OAc)2) into two Zirconium-based metal organic frameworks (MOFs) with different ligands to in situ construct Cu-based nanocatalysts for eCO2R. We show that Cu-ligand interactions crucially determine the transformation of Cu(OAc)2 during electrolysis, with biphenyl linkers forming agglomerated Cu2O particles and bipyridine linkers yielding highly dispersed Cu crystallites. This ligand-modulated Cu reconstruction diverges eCO2R towards C2 and C1 pathways, with agglomerated Cu2O particles producing C2+ products and smaller Cu crystallites achieving a maximum CH4 Faradaic efficiency (FE) of 60.3% ± 0.5% at 600 mA/cm2. In situ IR and Raman spectra unveil that larger Cu2O particles accumulate Cu-OH, increasing local alkalinity and *CO coverage, which favors asymmetric C-C coupling to yield C2+ products. Conversely, smaller Cu crystallites undergo rapid consumption of OH- and Cu-OH, decreasing alkalinity and promoting metal hydride (M-H) formation and sequential hydrogenation of *CO toward CH4 production. This study signifies the exploitation of metal-organic filler-host interactions to manipulate catalyst reconstruction for tailoring local environment towards selective eCO2R.