High-Nuclearity Copper Molecular Catalysts for Electrocatalytic CO-to-Acetate Conversion

Ligand-modified metal nanoclusters (NCs) have emerged as candidate materials for catalysis owing to their well-defined yet tunable structure and their metal centers' high nuclearity. We posited that NC-based catalytic behavior will depend on ligand properties, the accessibility of active sites, and their atomic configuration. We synthesized a series of Cu NC-based catalysts, tuned local hydrophobicity through ligand adjustment, balanced the ligand coverage and active site exposure, and found that we were, in this way, able to engender efficient electrosynthesis of acetate via CO electroreduction. Computation and operando spectroscopy show that asymmetric Cu-Cu sites, which determine the CO binding strength, impact the bifurcation step after C-C coupling. The best of these catalysts, Cu₁₃Nap, achieved an acetate Faradaic efficiency (FE) of 86% and an energy efficiency of 29% in a 5 bar system, exceeding the single C₂₊ FE of <50% previously achieved by NC-based catalysts.