Unravelling Kinetic and Thermodynamic Effects on the Growth of Gold Nanoplates by Liquid Transmission Electron Microscopy

Alloyeau, Damine, Walid Dachraoui, Yasir Javed, Hannen Belkahla, Guillaume Wang, Hélène Lecoq, Christian Ricolleau, et al., 2015
gold nanoplate material properties observed using in situ TEM
Image courtesy of Nano Letters

Abstract

The growth of colloidal nanoparticles is simultaneously driven by kinetic and thermodynamic effects that are difficult to distinguish. We have exploited in situ scanning transmission electron microscopy in liquid to study the growth of Au nanoplates by radiolysis and unravel the mechanisms influencing their formation and shape. The electron dose provides a straightforward control of the growth rate that allows quantifying the kinetic effects on the planar nanoparticles formation. Indeed, we demonstrate that the surface-reaction rate per unit area has the same dose-rate dependent behavior than the concentration of reducing agents in the liquid cell. Interestingly, we also determine a critical supply rate of gold monomers for nanoparticle faceting, corresponding to three layers per second, above which the formation of nanoplates is not possible because the growth is then dominated by kinetic effects. At lower electron dose, the growth is driven by thermodynamic and the formation and shape of nanoplates are directly related to the twin-planes formed during the growth.

Impact Statement

Mechanistic and kinetic study that examines the effect of electron dose on the growth and faceting of 2D and 3D gold nanoparticles in situ using LC-STEM.