Thermally Promoted Cation Exchange at the Solid State in the Transmission Electron Microscope: How It Actually Works

Alberto Casu, Miquel Lopez, Claudio Melis, Davide Deiana, Hongbo Li, Luciano Colombo, Andrea Falqui

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

Cation exchange offers a strong postsynthetic tool for nanoparticles that are unachievable via direct synthesis, but its velocity makes observing the onset of the reaction in the liquid state almost impossible. After successfully proving that cation exchange reactions can be triggered, performed, and followed live at the solid state by an in situ transmission electron microscopy approach, we studied the deep mechanisms ruling the onset of cation exchange reactions, i.e., the adsorption, penetration, and diffusion of cations in the host matrices of two crystal phases of CdSe. Exploiting an in situ scanning transmission electron microscopy approach with a latest generation heating holder, we were able to trigger, freeze, and image the initial stages of cation exchange with much higher detail. Also, we found a connection between the crystal structure of CdSe, the starting temperature, and the route of the cation exchange reaction. All the experimental results were further reviewed by molecular dynamics simulations of the whole cation exchange reaction divided in subsequent steps. The simulations highlighted how the cation exchange mechanism and the activation energies change with the host crystal structures. Furthermore, the simulative results strongly corroborated the activation temperatures and the cation exchange rates obtained experimentally, providing a deeper understanding of its phenomenology and mechanism at the atomic scale.
Original languageEnglish (US)
JournalACS Nano
DOIs
StatePublished - Aug 28 2023

Bibliographical note

KAUST Repository Item: Exported on 2023-08-31
Acknowledgements: Video_S1 was produced by Heno Hwang, scientific illustrator at KAUST, who is gratefully acknowledged. Dr. Alessandro Genovese from Kaust Core Laboratories, who participated to the initial in situ STEM experiments, is also very thankfully acknowledged. We acknowledge financial support from the King Abdullah University of Science and Technology (KAUST) baseline funding from Professor Andrea Falqui until the end of 2020. Since the beginning of 2021 we gratefully acknowledge financial support from the University of Milan, and from CRUI (Conferenza dei Rettori delle Università Italiane) to cover the open access fees.

ASJC Scopus subject areas

  • General Physics and Astronomy
  • General Materials Science
  • General Engineering

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