Dissecting Critical Factors for Electrochemical CO2 Reduction on Atomically Precise Au Nanoclusters

• Published in: Angewandte Chemie (International ed.) 2022-11, Vol.61 (47), p.e202211771-n/a
• Main Authors: Li, Site, Nagarajan, Anantha Venkataraman, Du, Xiangsha, Li, Yingwei, Liu, Zhongyu, Kauffman, Douglas R., Mpourmpakis, Giannis, Jin, Rongchao
• Format: Article
• Language: English
• Subjects: Atomically Precise Gold Nanoclusters; Carbon dioxide; Catalytic activity; Chemical reduction; CO2 Reduction; Density functional theory; Electrocatalysis; Electrocatalysts; Electrochemistry; Free energy; Heat of formation; INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Intermediates; Isomer Effects; Isomers; Nanoclusters; Selectivity; Size Effects
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.202211771

This work investigates the critical factors impacting electrochemical CO2 reduction reaction (CO2RR) using atomically precise Au nanoclusters (NCs) as electrocatalysts. First, the influence of size on CO2RR is studied by precisely controlling NC size in the 1–2.5 nm regime. We find that the electrocatalytic CO partial current density increases for smaller NCs, but the CO Faradaic efficiency (FE) is not directly associated with the NC size. This indicates that the surface‐to‐volume ratio, i.e. the population of active sites, is the dominant factor for determining the catalytic activity, but the selectivity is not directly impacted by size. Second, we compare the CO2RR performance of Au38 isomers (Au38Q and Au38T) to reveal that structural rearrangement of identical size NCs can lead to significant changes in both CO2RR activity and selectivity. Au38Q shows higher activity and selectivity towards CO than Au38T, and density functional theory (DFT) calculations reveal that the average formation energy of the key *COOH intermediate on the proposed active sites is significantly lower on Au38Q than Au38T. These results demonstrate how the structural isomerism can impact stabilization of reaction intermediates as well as the overall CO2RR performance of identical size Au NCs. Overall, this work provides important structure–property relationships for tailoring the NCs for CO2RR. The key factors in nanocluster (NCs)‐catalyzed electrochemical CO2 reduction (CO2RR) are studied by comparing Au NCs with different sizes as well as Au38 isomer. Overall, the smaller size enables a higher activity due to the higher surface‐to‐volume ratio, while the isomerism of the same‐sized NCs can lead to significant changes in both activity and selectivity due to the difference in average formation energy of the key *COOH intermediate.