Atomically Precise Gold Nanoclusters as Model Catalysts for Identifying Active Sites for Electroreduction of CO2​.

Accurate identification of active sites is critical for elucidating catalytic reaction mechanisms and developing highly efficient and selective electrocatalysts. Herein, we report the atomic-level identification of active sites using atomically well-defined gold nanoclusters (Au NCs) Au 25 , Au 38 , and Au 144 as model catalysts in the electrochemical CO 2 reduction reaction (CO 2 RR). The studied Au NCs exhibited remarkably high CO 2 RR activity, which increased with increasing NC size. Electrochemical and X-ray photoelectron spectroscopy analyses revealed that the Au NCs were activated by removing one thiolate group from each staple motif at the beginning of CO 2 RR. In addition, density functional theory calculations revealed higher charge densities and upshifts of d -states for dethiolated Au sites. The structure-activity properties of the studied Au NCs confirmed that dethiolated Au sites were the active sites and that CO 2 RR activity was determined by the number of active sites on the cluster surface.