Pd nanoparticle formation in ionic liquid thin films monitored by in situ vibrational spectroscopy

Beitrag in einer Fachzeitschrift
(Originalarbeit)


Details zur Publikation

Autor(en): Mehl S, Toghan A, Bauer T, Brummel O, Taccardi N, Wasserscheid P, Libuda J
Zeitschrift: Langmuir
Jahr der Veröffentlichung: 2015
Band: 31
Heftnummer: 44
Seitenbereich: 12126-12139
ISSN: 1520-5827


Abstract


Ionic liquids (ILs) are flexible reaction media and solvents for the synthesis of metal nanoparticles (NPs). Here, we describe a new preparation method for metallic NPs in nanometer thick films of ultraclean ILs in an ultrahigh vacuum (UHV) environment. CO-covered Pd NPs are formed by simultaneous and by sequential physical vapor deposition (PVD) of the IL and the metal in the presence of low partial pressures of CO. The film thickness and the particle size can be controlled by the deposition parameters. We followed the formation of the NPs and their thermal behavior by time-resolved IR reflection absorption spectroscopy (TP-IRAS) and by temperature-programmed IRAS (TR-IRAS). Codeposition of Pd and [CCIm][OTf] in CO at 100 K leads to the growth of homogeneous multilayer films of CO-covered Pd aggregates in an IL matrix. The size of these NPs can be controlled by the metal fraction in the co-deposit. With increasing metal fraction, the size of the Pd NPs also increases. At very low metal content, small Pd carbonyl-like species are formed, which bind CO in on-top geometry only. Upon annealing, the [OTf] anion coadsorbs at the NP surface and partially displaces CO. Co-adsorption of CO and IL is indicated by a strong red-shift of the CO stretching bands. While the weakly bound on-top CO is mainly replaced below the melting transition of the IL, coadsorbate shells with bridge-bonded CO and IL are stable well above the melting point. Larger three-dimensional Pd NPs can be prepared by PVD of Pd onto a solid [CCIm][OTf] film at 100 K. Upon annealing, on-top CO desorbs from these NPs below 200 K. Upon melting of the IL film, the CO-covered Pd NPs immerse into the IL and again form a stable coadsorbate shell that consists of bridge-bonded CO and the IL.



FAU-Autoren / FAU-Herausgeber

Bauer, Tanja
Professur für Physikalische Chemie
Brummel, Olaf Dr.
Professur für Physikalische Chemie
Libuda, Jörg Prof. Dr.
Professur für Physikalische Chemie
Mehl, Sascha
Professur für Physikalische Chemie
Taccardi, Nicola Dr.
Lehrstuhl für Chemische Reaktionstechnik
Wasserscheid, Peter Prof. Dr.
Lehrstuhl für Chemische Reaktionstechnik


Zitierweisen

APA:
Mehl, S., Toghan, A., Bauer, T., Brummel, O., Taccardi, N., Wasserscheid, P., & Libuda, J. (2015). Pd nanoparticle formation in ionic liquid thin films monitored by in situ vibrational spectroscopy. Langmuir, 31(44), 12126-12139. https://dx.doi.org/10.1021/acs.langmuir.5b03386

MLA:
Mehl, Sascha, et al. "Pd nanoparticle formation in ionic liquid thin films monitored by in situ vibrational spectroscopy." Langmuir 31.44 (2015): 12126-12139.

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Zuletzt aktualisiert 2018-24-11 um 20:50