Title: Pt ₈ cluster on alumina under a pressure of hydrogen: Support-dependent reconstruction from first-principles global optimization

Abstract

Alumina supported Pt nano clusters under hydrogen environment play a crucial role for many heterogeneous catalysis applications. As such, we conducted grand canonical genetic algorithm (GCGA) simulations for supported Pt ₈ clusters in hydrogen gas environment to study the intra-cluster, cluster-support, and cluster-adsorbate interactions. Two alumina surfaces, α-Al ₂O ₃(0001) and $γ$-Al ₂O ₃(100), and two conditions T=600°C, p _H2 = 0.1bar and T=25°C, p _H2 = 1.0 bar were considered corresponding to low and high hydrogen chemical potential $μ$ _H, respectively. The low free energy ensemble of Pt ₈ is decorated by a medium (2–12 H), resp. high (20–30 H), number of hydrogen atoms under equilibrium at low $μ$ _H, respectively, high $μ$ _H, and undergoes different morphology transformations on the two surfaces. On α-Al2O3(0001), Pt8 is mostly 3D but very fluxional in structure at low μH and converts to open one-layer 2D structures with minimal fluxionality at high μH, whereas on $γ$-Al ₂O ₃(100), the exact opposite occurs, and Pt ₈ clusters present one-layer 2D shapes at low $μ$ _H and switch into compact 3D shapes under high $μ$ _H, during which the Pt ₈ cluster preserves moderate fluxionality. Further analysis reveals similar Pt–Pt bond length increase whenmore » switching from low $μ$ _H to high $μ$ _H on both surfaces, though morphology transformations are different. Electronic structure analysis shows the existence of bonding interactions between Pt and Lewis acidic Al ³⁺ sites along with the Pt – O interaction, which implies the necessity to include Al neighbors to discuss the electronic structure of small Pt clusters.« less

Authors:

Sun, Geng  ^[1];

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• Search DOE PAGES for ORCID "0000-0003-2123-7464"
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Alexandrova, Anastassia N.  ^[2];

• Search DOE PAGES for author "Alexandrova, Anastassia N."
• Search DOE PAGES for ORCID "0000-0002-3003-1911"
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Sautet, Philippe  ^[2]

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• Search DOE PAGES for ORCID "0000-0002-8444-3348"
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+ Show Author Affiliations

1. Univ. of California, Los Angeles, CA (United States)
2. Univ. of California, Los Angeles, CA (United States); California NanoSystems Inst., Los Angeles, CA (United States)

Publication Date:

2019-11-20

Research Org.:

Univ. of California, Los Angeles, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). National Energy Research Scientific Computing Center (NERSC)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Chemical Sciences, Geosciences & Biosciences Division; USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Scientific User Facilities Division

OSTI Identifier:

1594248

Grant/Contract Number:  

SC0019152; DEAC02-05CH11231; AC02- 06CH11357

Resource Type:

Accepted Manuscript

Journal Name:

Journal of Chemical Physics

Additional Journal Information:

Journal Volume: 151; Journal Issue: 19; Journal ID: ISSN 0021-9606

Publisher:

American Institute of Physics (AIP)

Country of Publication:

United States

Language:

English

Subject:

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Global optimization; Pt cluster; alumina; cluster fluxionality