Anomalous Growth Rate of Ag Nanocrystals Revealed by in situ STEM

Abstract

In situ microscopy of colloidal nanocrystal growth offers a unique opportunity to acquire direct and straightforward data for assessing classical growth models. Here, we observe the growth trajectories of individual Ag nanoparticles in solution using in situ scanning transmission electron microscopy. For the first time, we provide experimental evidence of growth rates of Ag nanoparticles in the presence of Pt in solution that are significantly faster than predicted by Lifshitz-Slyozov-Wagner theory. We attribute these observed anomalous growth rates to the synergistic effects of the catalytic properties of Pt and the electron beam itself. Transiently reduced Pt atoms serve as active sites for Ag ions to grow, thereby playing a key role in controlling the growth kinetics. Electron beam illumination greatly increases the local concentration of free radicals, thereby strongly influencing particle growth rate and the resulting particle morphology. Through a systematic investigation, we demonstrate the feasibility of utilizing these synergistic effects for controlling the growth rates and particle morphologies at the nanoscale. Our findings not only expand the current scope of crystal growth theory, but may also lead to a broader scientific application of nanocrystal synthesis.

Liquid cell transmission electron microscopy and its applications

“…Abellan et al [93] visualized how, by adding a capping agent tri-n-octylphosphine (TOP) to the solution, precise size control of the grown Pd nanoparticle to sub-3 nm can be achieved. Ge et al [94] showed anomalously fast growth rates of Ag nanoparticles when the growth took place adjacent to Pt, providing experimental proof of the catalytic effect of Pt on the growth of nanomaterials. A future avenue for such in situ TEM experiments could be to use the liquid flow lines into the liquid cell to inject different reactants at sequential stages, allowing the controlled growth of more complex nanostructures.…”

In situ liquid transmission electron microscopy reveals self-assembly-driven nucleation in radiolytic synthesis of iron oxide nanoparticles in organic media

“…In fact, it has already been observed that the electron dose may provide a direct control of the formation kinetics and the morphology of Au, Ag, Pt and mixed oxides from aqueous solutions. [68][69][70][71][72][73][74] First, we used the conventional TEM mode to provide a high electron dose, since the observation area is continuously irradiated. With a beam current of 150 pA, the electron dose is about 9400 e − nm −2 s −1 .…”

Importance of Monitoring the Synthesis of Light‐Interacting Nanoparticles – A Review on In Situ, Ex Situ, and Online Time‐Resolved Studies

“…For metal nanoparticles, the literature contains a considerable number of studies for the synthesis of Au, [61,63,175,195,239,[242][243][244] Ag, [227,241,[245][246][247][248][249] and Pt nanoparticles [104,225,[250][251][252] with in situ/online analytics (refer to Table 2 for more studies). However, for Mg and Al, only ex situ kinetic studies have been reported in batch.…”

“…[267] It provides interesting capabilities for the visual study of material transformations and particle growth. [239,247,248,249,256,260,268] Most of the studies with in situ TEM listed in Table 2 reported a total reaction time ranging from seconds to a few minutes when using a liquid-TEM cell (e.g., ≈25 s to ≈7 min) in contrast to studies with conventional batch reactors which report longer reaction times normally until completion is reached. An example of such a study was reported by Zheng et al [104] for the synthesis of platinum nanoparticles.…”