Poisoning Electrocatalytic CO₂ Conversion to CO by Adding a μ₄-S Atom on Au₆₀ Nanocluster

Atomically precise gold nanoclusters (APGNCs) have received considerable concern in electrocatalytic carbon dioxide reduction reaction (CO2RR). The investigation of the CO2RR of APGNCs with a surface single-atom difference remains challenging. Herein, the successive addition of a surface sulfur atom (μ4-S) on Au60 was concurrently realized via a modified ligand exchange. The additional μ4-S makes the outer three kernel gold atoms in situ transform into staple gold atoms without altering other parts, endowing them with optimal model catalysts. Notably, Au60S6 exhibited high activity and CO selectivity over 95% within the entire test potentials, which decreased with the introduction of a μ4-S. DFT simulations indicate that the d-band center of the gold active site upshifts toward the Fermi level with the addition of a μ4-S, which strengthens the adsorption of intermediates, raises the energy barriers for CO desorption. This work provides an unprecedented paradigm for understanding structure–property relationships at the level of a surface single atom.