Title: Structural Analysis and Electrochemical Properties of Bimetallic Palladium-Platinum Aerogels Prepared by a Two-Step Gelation Process

Abstract

Multimetallic aerogels have emerged as promising unsupported and high-surface-area metal materials for different applications in heterogeneous catalysis and electrochemistry, which are fabricated using a gelation process characterized by the controlled aggregation of metallic nanoparticles to form a macroscopic network structure in aqueous solution. However, the achievement of the structural homogeneity of the multimetallic aerogels in terms of the diameter of the nanochains and the chemical composition at the nano- and the macro-scale is still a great challenge. In this paper, we investigated two Pd-Pt aerogels prepared by the two-step gelation method. The structural homogeneity and chemical distribution of both metals inside the aerogels were analyzed by using high-resolution (scanning) transmission microscopy, energy-dispersive X-ray spectroscopy, extended X-ray absorption fine structure spectroscopy and cyclic voltammetry. The Pd-Pt aerogels show the presence of Pd/Pt-rich domains inside the long-range framework. It is evident that the initial monometallic features dominate over alloying during the gelation process. Although the same synthetic approach for Pd-Pt aerogels with different atomic ratios was used, we observed that the sizes of these monometallic domains varied strongly between the Pd-rich and Pt-rich aerogels. The presence of such metal clusters influenced the electrochemical robustness of the Pd-Pt aerogels dramatically. Further, electrochemical durabilitymore » investigations revealed that the aerogels with a high content of Pd are less stable because of the gradual dissolution of the less noble metal particularly inside the Pd-rich domains. A chemical and structural homogeneity might improve the lifetime of the Pd-Pt aerogels under electrochemical conditions. In this work, we provide a better understanding of the structure and chemical distribution of the bimetallic aerogel framework prepared by the two-step gelation process.« less

Authors:

Oezaslan, Mehtap ^[1]; Herrmann, Anne-Kristin ^[2]; Werheid, Matthias ^[2]; Frenkel, Anatoly I. ^[3]; Nachtegaal, Maarten ^[4]; Dosche, Carsten ^[5]; Laugier Bonnaud, Céline ^[4]; Yilmaz, Hale Ceren ^[4]; Kühn, Laura ^[2]; Rhiel, Erhard ^[6]; Gaponik, Nikolai ^[2]; Eychmüller, Alexander ^[2]; Schmidt, Thomas Justus ^[7]

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+ Show Author Affiliations

1. Paul Scherrer Inst. (PSI), Villigen (Switzerland); Carl von Ossietzky Univ., Oldenburg (Germany)
2. Technische Univ. Dresden (Germany)
3. Stony Brook Univ., NY (United States)
4. Paul Scherrer Inst. (PSI), Villigen (Switzerland)
5. Carl von Ossietzky Univ., Oldenburg (Germany)
6. Carl von Ossietzky University of Oldenburg (Germany)
7. Paul Scherrer Inst. (PSI), Villigen (Switzerland); Eidgenoessische Technische Hochschule (ETH), Zurich (Switzerland)

Publication Date:

Fri Oct 07 00:00:00 EDT 2016

Research Org.:

Univ. of Illinois at Urbana-Champaign, IL (United States)

Sponsoring Org.:

USDOE Office of Science (SC); German Research Foundation (DFG); Swiss National Science Foundation (SNF); European Research Council (ERC); Bundesministerium für Bildung, Wissenschaft, Forschung und Technologie (BMBF)

OSTI Identifier:

1533126

Grant/Contract Number:  

FG02-03ER15476

Resource Type:

Accepted Manuscript

Journal Name:

ChemCatChem

Additional Journal Information:

Journal Volume: 9; Journal Issue: 5; Journal ID: ISSN 1867-3880

Publisher:

ChemPubSoc Europe

Country of Publication:

United States

Language:

English

Subject:

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; chemistry; electrochemistry; gels; palladium; platinum; self-assembly