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Creators/Authors contains: "Nagarajan, Anantha Venkataraman"

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  1. Atomically precise, thiolate-protected gold nanoclusters (TPNCs) exhibit remarkable catalytic performance for the electrochemical reduction of carbon dioxide (CO 2 R) to CO. The origin of their high CO 2 R activity and selectivity has been attributed to partial ligand removal from the thiolate-covered surfaces of TPNCs to expose catalytically active sulfur atoms. Recently, heterometal doped (alloy) TPNCs have been shown to exhibit enhanced CO 2 R activity and selectivity compared to their monometallic counterparts. However, systematic studies on the effect of doping (metal type and location on TPNC) on active site exposure and CO 2 R activity are missing in literature. Herein, we apply Density Functional Theory calculations to investigate the effect of heterometal (Pt, Pd, Hg and Cd) doping of Au 25 (SR) 18 TPNC on the active site exposure and CO 2 R activity and selectivity. We reveal that doping significantly modifies relevant TPNC electronic properties, such as electron affinity, while also altering partial ligand removal and carboxyl (*COOH) intermediate formation energies. Furthermore, we demonstrate that changing the dopant ( e.g. Hg) position can change the selectivity of the TPNC towards CO (g) or H 2(g) formation, highlighting the importance of dopant locations in TPNC-based CO 2 R. Most notably, we report a universal ( i.e. capturing different dopant types and positions) linear trend between the ligand removal energy and i) the *COOH formation energy, as well as, ii) the hydrogen (*H) formation energy on the different alloy TPNCs. Thus, utilizing the ligand removal energy as a descriptor for CO 2 RR activity and selectivity, our work opens new avenues for accelerated computational screening of different alloy TPNCs for electrocatalytic CO 2 R applications. 
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  2. Abstract

    This work investigates the critical factors impacting electrochemical CO2reduction 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 Au38isomers (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.

     
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  3. Abstract

    This work investigates the critical factors impacting electrochemical CO2reduction 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 Au38isomers (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.

     
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  4. null (Ed.)