Metallic Hydrogen in Atomically Precise Gold Nanoclusters

Journal Article · Wed May 17 04:00:00 EDT 2017 · Chemistry of Materials

DOI:https://doi.org/10.1021/acs.chemmater.7b00776· OSTI ID:1479679

Hu, Guoxiang ^[1]; Tang, Qing ^[1]; Lee, Dongil ^[2]; Wu, Zili ^[3]; Jiang, De-en ^[1]

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1. Department of Chemistry, University of California, Riverside, California 92521, United States
2. Department of Chemistry, Yonsei University, Seoul 120-749, Korea
3. Chemical Sciences Division and Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States

Hydrogen–metal interaction is the foundation of many technologies and processes, but how hydrogen behaves in atomically precise gold nanoclusters remains unknown even though they have been used in hydrogenation catalysis and water splitting. Herein, we investigate how hydrogen interacts with [Au25(SR)18]q clusters and mono-atom-doped bimetallic [M1Au24(SR)18]q clusters (M = Pt, Pd, Ag, Cu, Hg, or Cd) from first principles. We find that hydrogen behaves as a metal in these clusters and contributes its 1s electron to the superatomic free-electron count. This opposite behavior compared to that of the hydride in Cu and Ag clusters allows the small hydrogen to interstitially dope the gold clusters and tune their superatomic electronic structure. The doping energetics shows that when an eight-electron superatom is formed after H doping, the binding energy of H is much stronger, while binding of H with an already eight-electron superatom is much weaker. Indeed, frontier orbitals and the HOMO–LUMO gaps of [Au25H1(SR)18]0, [Au25H2(SR)18]+, [PtAu24H2(SR)18]0, [PdAu24H2(SR)18]0, [AgAu24H(SR)18]0, and [CuAu24H(SR)18]0 all have very similar features, because they are all eight-electron superatoms. By calculating the Gibbs free energies of hydrogen adsorption, we predict that PtAu24(SR)18, PdAu24(SR)18, and center-doped CuAu24(SR)18 can be good electrocatalysts for the hydrogen evolution reaction.

• Research Organization: Lawrence Berkeley National Laboratory-National Energy Research Scientific Computing Center
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
• DOE Contract Number: AC02-05CH11231
• OSTI ID: 1479679
• Journal Information: Chemistry of Materials, Journal Name: Chemistry of Materials Journal Issue: 11 Vol. 29; ISSN 0897-4756
• Country of Publication: United States
• Language: English