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Nucleation & growth of nanomaterials in liquid phase

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Liquid-phase syntheses are very versatile methods to fabricate complex nanomaterials with controlled size, shape and atomic structure. However, because of the lack of efficient tool to visualize nano-object dynamics in liquids, the theories on the nucleation and growth mechanisms remain mostly speculative and sometime contradictory. For a long time, this bottleneck has favored the use of empirical approaches to improve synthesis protocols. To address this fundamental issue, the MPQ Lab has been the first laboratory in France to exploit liquid-cell TEM with the view to provide in situ insights on the formation mechanisms of anisotropic gold nanoparticles and bimetallic nanostructures. Remarkably, this technique allows distinguishing kinetic effects that depends on the growth speed and thermodynamic effects dictated by the stability of nanomaterials within its environment. Therefore, we can take a fresh look at many strategies employed by colloidal chemists to control the size and shape of nanostructures, including seed-mediated synthesis, functionalization methods, kinetically-controlled growth, but also chemical etching and galvanic replacement. These mechanistic information open up the unique opportunity to confirm existing theory or to reveal surprising growth processes, so that we can gain control over the fabrication of nanomaterials and design more sophisticated nano-architectures.

Top : Schematic and cross-section view of a liquid cell exploited to study the dynamics of nano-objects in liquid by TEM (© Protochips). Down : Growth of a gold nanoplate in methanol.

Project :
PLASMAG Project (SEAM Labex)

Main publications :

Exploring the Formation of Symmetric Gold Nanostars by Liquid-Cell Transmission Electron Microscopy
Nabeel Ahmad, Guillaume Wang, Jaysen Nelayah, Christian Ricolleau, and Damien Alloyeau
Nano Lett. 17 (7), 4194–4201 (2017)

Driving Reversible Redox Reactions at Solid / Liquid Interfaces with the Electron Beam of a Transmission Electron Microscope
N. Ahmad, G. Wang, J. Nelayah, C. Ricolleau, D. Alloyeau
Journal of Microscopy DOI : 10.1111/jmi.12568 (2017)

Growth of dendritic nanostructures by liquid-cell transmission electron microscopy : a reflection of the electron-irradiation history
N. Ahmad, Y. Bouar, C. Ricolleau, D. Alloyeau
Advanced Structural and Chemical Imaging (2016), 2 (1), 9-19

Unravelling Kinetic and Thermodynamic Effects on the Growth of Gold Nanoplates by Liquid Transmission Electron Microscopy
Damien Alloyeau, Walid Dachraoui, Yasir Javed, Hannen Belkahla, Guillaume Wang, Hélène Lecoq, Souad Ammar, Ovidiu Ersen, Andreas Wisnet, Florence Gazeau, and Christian Ricolleau
Nano Letters 15, 2574−2581 (2015)