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 (CO 2 RR). The investigation of the CO 2 RR of APGNCs with a surface single-atom difference remains challenging. Herein, the successive addition of a surface sulfur atom (μ 4 -S) on Au 60 was concurrently realized via a modified ligand exchange. The additional μ 4 -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, Au 60 S 6 exhibited high activity and CO selectivity over 95% within the entire test potentials, which decreased with the introduction of a μ 4 -S. DFT simulations indicate that the d-band center of the gold active site upshifts toward the Fermi level with the addition of a μ 4 -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.