Controlled silver-shell growth on gold nanorods studied by in situ liquid cell TEM techniques

Beitrag bei einer Tagung
(Konferenzbeitrag)


Details zur Publikation

Autorinnen und Autoren: Hutzler A, Branscheid R, Schmutzler T, Jank M, Frey L, Spiecker E
Jahr der Veröffentlichung: 2017
Tagungsband: Microscopy Conference 2017 (MC 2017) - Proceedings
Seitenbereich: 600 - 601
Sprache: Englisch


Abstract

Liquid cell transmission electron microscopy (LCTEM) enables the observation of dynamic processes at
the place of the event in real time that is in situ. An early concept of this method has already been
suggested in 1944 by Abrams and McBain [1] and could be realized nearly 60 years later in 2003 by
Williamson et al. [2]. Since that, much effort has been put into characterizing various reactions in
material, biological, and electrochemical systems.

Anisotropic core-shell nanostructures are highly attractive for plasmonic applications like e.g. sensors,
light guiding or labeling, because their plasmon resonance frequency can be variably adjusted over a
wide spectral range via a simple variation of the shell thickness as already shown by Becker et al. [3].
Here we apply LCTEM to induce and to investigate the growth of silver-shell from aqueous silver nitrate
(AgNO3) solution on cetrimonium bromide (CTAB) stabilized gold nanorods. For this purpose, a new,
simplified liquid cell design is utilized, which is not only capable being used for conventional, but also for
analytic TEM techniques like energy dispersive x-ray spectroscopy (EDXS) and electron tomography. To
achieve that, the fluid is enclosed between a structured silicon nitride membrane and a second few layer
graphene membrane, leaving one side of the cell plane, as shown elsewhere [4]. For the experiments, a
conventional TEM specimen holder is used together with a Philips CM 30 and a FEI Titan³ Themis, both
operated at 300 kV.

It could be shown that silver bromide (AgBr) is forming, which components are originating from CTAB
and AgNO3. AgBr is subsequently being reduced by solvated electrons acting as reducing agent. These
free electrons are generated intrinsically by electron beam irradiation of the aqueous solution. The silver
atoms can then nucleate and crystallize at different nucleation centers. One possible nucleation center is
the surface of the present gold nanorods, where an epitaxial, defect free growth of a silver shell can be
observed (cf. Fig. 1 and Fig. 2). The whole process is slowed down compared to bulk reactions because
of the confinement of the solution to a narrow channel and thus because of a higher liquid viscosity
hindering diffusion. Nevertheless, the growth rate of silver perpendicular to the longitudinal direction of
the nanorods is considerably higher compared to the growth rate in the parallel direction. Furthermore, a
dose dependent and reversible layer-by-layer dissolution of AgBr particles, acting as silver sources, is
observable (cf. Fig. 3). Here, the reduction, and thus the annihilation of solvated silver ions at higher
electron dose rate conditions shifting the solubility product to nonequilibrium state, so that AgBr dissolves
to restore this equilibrium. In contrast to this process, counter reactions prevail at lower dose conditions.
Here, the formation of silver ions is favored until the solubility is being exceeded and crystallization of
AgBr takes place.

The experiments done within this study show that this new liquid cell design is appropriate for solving
material scientific issues. In particular, the planar surface of the liquid cell as well as the large viewing
areas allow for improved performance of analytical TEM techniques like EDXS and electron tomography
making the cell architecture capable of more comprehensive investigations into complex material
systems.


FAU-Autorinnen und Autoren / FAU-Herausgeberinnen und Herausgeber

Branscheid, Robert
Lehrstuhl für Werkstoffwissenschaften (Mikro- und Nanostrukturforschung)
Frey, Lothar Prof. Dr.
Lehrstuhl für Elektronische Bauelemente
Hutzler, Andreas Dr.-Ing.
Lehrstuhl für Elektronische Bauelemente
Schmutzler, Tilo
Professur für Nanomaterialcharakterisierung (Streumethoden)
Spiecker, Erdmann Prof. Dr.
Lehrstuhl für Werkstoffwissenschaften (Mikro- und Nanostrukturforschung)


Zusätzliche Organisationseinheit(en)
Graduiertenkolleg 1896/2 In situ Mikroskopie mit Elektronen, Röntgenstrahlen und Rastersonden
Interdisziplinäres Zentrum, Center for Nanoanalysis and Electron Microscopy (CENEM)
Lehrstuhl für Werkstoffwissenschaften (Mikro- und Nanostrukturforschung)


Einrichtungen weiterer Autorinnen und Autoren

Fraunhofer-Institut für Integrierte Systeme und Bauelementetechnologie (IISB)


Zitierweisen

APA:
Hutzler, A., Branscheid, R., Schmutzler, T., Jank, M., Frey, L., & Spiecker, E. (2017). Controlled silver-shell growth on gold nanorods studied by in situ liquid cell TEM techniques. In Microscopy Conference 2017 (MC 2017) - Proceedings (pp. 600 - 601). Lausanne, CH.

MLA:
Hutzler, Andreas, et al. "Controlled silver-shell growth on gold nanorods studied by in situ liquid cell TEM techniques." Proceedings of the Microscopy Conference 2017, Lausanne 2017. 600 - 601.

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