Oxygen Electrocatalysis by [Au25(SR)18]: Charge, Doping, and Ligand Removal Effect

Considering the promising prospects of Au25(SR)18 q and its alloy clusters in numerous fundamental catalysis research studies derived from their well-defined structures, developing a deep understanding of the structure–property correlation becomes significantly urgent. Herein, we explored a prototyp...

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Veröffentlicht in:ACS catalysis 2021-07, Vol.11 (13), p.7957-7969
Hauptverfasser: Sun, Fang, Deng, Chaofang, Tian, Shufang, Tang, Qing
Format: Artikel
Sprache:eng
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Zusammenfassung:Considering the promising prospects of Au25(SR)18 q and its alloy clusters in numerous fundamental catalysis research studies derived from their well-defined structures, developing a deep understanding of the structure–property correlation becomes significantly urgent. Herein, we explored a prototype [Au25(SR)18] q cluster, monoatom-doped bimetallic [MAu24(SR)18] q clusters (M = Pt, Pd, Ag, Cu, Hg, or Cd), and their singly deligated M-exposure and S-exposure systems as electrocatalysts toward O2 reduction reaction (ORR) at the acidic medium. Theoretical simulations reveal that the fully ligand-protected clusters prefer H2O2 formation through the two-electron (2e–) mechanism, whereas the dethiolated clusters prefer to proceed via the four-electron (4e–) pathway for H2O production. Among them, a single Hg substitution at the staple site, namely, fully ligated [HgAu24(SCH3)18]0–O and dethiolated [HgAu24(SCH3)17]0–O with an exterior −SCH3 removal has great potential to realize high-efficiency 2e– and 4e– ORR, with an ultralow overpotential of 0.08 and 0.43 V, respectively. The correlation between adsorption of oxygenated intermediates and Bader charge as well as active metal d-band center sheds light on the underlying origin of selectivity and activity. Besides, the analysis of projected density of states suggests that monoatom doping has a mild modification to the s-bands of Au, but the removal of the −SR ligand can obviously amend the electronic structure of Au-s states. Particularly, in contrast to the strong d-electron effect in Au25 q and other doped MAu24 q clusters, the s-electron effect from the staple-doped Hg atom shows great promise in optimizing the intermediate adsorption and functions as a distinguished electrocatalyst for O2 reduction. These insights provide useful guidelines for the design of high-efficiency metal nanocluster electrocatalysts by implementing late-transition metal or p-block metal with a strong s- or p-electron effect to achieve superior ORR activity.
ISSN:2155-5435
2155-5435
DOI:10.1021/acscatal.1c01030