Structural Analysis and Electrochemical Properties of Bimetallic Palladium–Platinum Aerogels Prepared by a Two‐Step Gelation Process

Medientyp: E-Artikel

Titel: Structural Analysis and Electrochemical Properties of Bimetallic Palladium–Platinum Aerogels Prepared by a Two‐Step Gelation Process

Beteiligte: Oezaslan, Mehtap [VerfasserIn]; Herrmann, Anne-Kristin [VerfasserIn]; Werheid, Matthias [VerfasserIn]; Frenkel, Anatoly [VerfasserIn]; Nachtegaal, Maarten [VerfasserIn]; Dosche, Carsten [VerfasserIn]; Laugier Bonnaud, Celine [VerfasserIn]; Ceren Yilmaz, Hale [VerfasserIn]; Kühn, Laura [VerfasserIn]; Rhiel, Erhard [VerfasserIn]; Gaponik, Nikolai [VerfasserIn]; Eychmüller, Alexander [VerfasserIn]; Schmidt, Thomas Justus [VerfasserIn]

Erschienen: Weinheim : Wiley VCH Verlag, [2018]

Sprache: Englisch

DOI: 10.1002/cctc.201600667

RVK-Notation: VA 1120 : Zeitschriften

Schlagwörter: bimetallisches Aerogel ; Chemie und Pharmazie ; zweistufiges Gelierverfahren ; two-step gelation process ; high-resolution scanning transmission electron microscopy ; chemical homogeneity ; hochauflösende Rastertransmissionselektronenmikroskopie ; science-chemistry ; pharmacology ; Pd-Pt ; chemische Homogenität ; bimetallic aerogel

Entstehung:

Anmerkungen: Hinweis: Link zum Artikel, der zuerst in der Zeitschrift "ChemCatChem" in der Wiley Online Library erschienen ist. URL: https://doi.org/10.1002/cctc.201600667 DOI: 10.1002/cctc.201600667
Quelle: ChemCatChem (2017), 9(5), S. 798-808. E-ISSN 1867-3899. DOI: 10.1002/cctc.201600667

Beschreibung: Multi-metallic aerogels have emerged as a promising unsupported, high surface area-based metal material for different applications in heterogeneous catalysis and electrochemistry. The fabrication of these multi-metallic aerogels is based on a complex gelation process which is characterized by controlled aggregation of metallic nanoparticles to form a macroscopic network structure in aqueous solution. However, achieving structural homogeneity of the multi-metallic aerogels in terms of diameter of the nanochains and chemical composition at the nano- as well as at the macro-scale is still a great challenge. In this paper, we show the characterization of two Pd-Pt aerogels prepared by the two-step gelation method. The structural homogeneity and chemical distribution of both metals (Pd and Pt) inside the aerogels were analyzed using high-resolution (scanning) transmission microscopy (HR(S)TEM), energy-dispersive X-ray spectroscopy (EDX), extended X-ray absorption fine structure (EXAFS) spectroscopy, and cyclic voltammetry. Based on the microscopic and spectroscopic results, 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 strongly varied between the Pd-rich and Pt-rich aerogels. For instance, the Pd-rich aerogels showed larger clusters with a size range from few nanometers up to several tens of nanometers, while the dimension of the clusters of the Pt-rich aerogels varies from the sub-nanometers to a few nanometers. The presence of the metal clusters strongly influenced the electrochemical robustness of these Pd-Pt aerogels. Electrochemical durability investigations revealed that the aerogels with a high content of Pd are less stable due to the gradual dissolution of the less noble metal in particular inside the Pd-rich domains. A better chemical and structural homogeneity might improve the life-time of the Pd-Pt aerogels under electrochemical conditions. In this work, we provide a better understanding about the structure and chemical distribution of the bimetallic aerogel framework prepared by the two step gelation process.

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