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

• Published in: Angewandte Chemie International Edition Vol. 60; no. 26; pp. 14563 - 14570
• Main Authors: Seong, Hoeun, Efremov, Vladimir, Park, Gibeom, Kim, Hyunwoo, Yoo, Jong Suk, Lee, Dongil
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 21.06.2021
• Edition: International ed. in English
• Subjects: Carbon dioxide; Catalysts; Charge density; Chemical reduction; cluster compounds; CO2 reduction; Density functional theory; Electrocatalysts; Electrochemistry; Gold; heterogeneous catalysis; Nanoclusters; Photoelectron spectroscopy; Photoelectrons; reaction mechanism; Reaction mechanisms; S ligands; reaction mechanisms; cluster compounds; heterogeneous catalysis; reduction; S ligands
• ISSN: 1433-7851; 1521-3773; 1521-3773
• DOI: 10.1002/anie.202102887

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) Au25, Au38, and Au144 as model catalysts in the electrochemical CO2 reduction reaction (CO2RR). The studied Au NCs exhibited remarkably high CO2RR 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 CO2RR. 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 CO2RR activity was determined by the number of active sites on the cluster surface. Active sites for the electroreduction of CO2 to CO were experimentally identified for the first time using atomically well‐defined Au nanoclusters. The partially dethiolated Au site bridging S and Au atoms in the staple motif exhibits higher charge density and upshift of d‐states, which promote the catalytic process by stabilizing the reaction intermediate.