Effect of temperature on electron beam-driven growth of Pd nanocrystals

How does temperature affect the radiolytic growth of Pd nanocrystals?

Serin Lee, Frances Ross, and Jeung Hun Park from MIT and Princeton University, along with Tommy Watanabe from Proterial Ltd. published work using the Hummingbird Scientific In-situ Liquid Heating TEM sample holder to grow Pd nanocrystals in a liquid heating cell under transmission electron microscopy (TEM). The team combined kinetic analysis of time-lapse videos of the nanocrystal growth at 25 °C and 50 °C with a temperature-dependent radiolysis model to identify growth regimes and their underlying mechanisms.

Videos showing growth of Pd nanocrystals under radiolysis at a) 25 °C and b) 50 °C. Kinetic analysis showing log(r) vs. log(t) for nanocrystal growth at c) 25 °C and d) 50 °C. All nanocrystals tracked nucleated within 1-2 s. Copyright © 2024 Wiley-VCH GmbH

Two growth regimes were distinguished. At early timestamps, growth is surface reaction-limited and increases with temperature. Beyond a transition time, the growth is limited by supply of Pd ions via diffusion and reducing hydrated electrons, leading to reduced temperature dependence once the two are in balance. The observed formation of a branched rough microstructure is typically indicative of this diffusion-limited growth, but forms here during the surface reaction-limited regime. The liquid heating holder, combined with radiolysis calculations, has enabled investigation of the role of temperature in surfactant free nanocrystal synthesis, and will inform future optimization of nanocrystal structure, size, and morphology.

Reference: Serin Lee, Tommy Watanabe, Frances M. Ross, Jeung Hun Park, Small XX (X) 2403969 (2024) DOI: 10.1002/smll.202403969

View All News