Sintering Mechanism of Core@Shell Metal@Metal-Oxide Nanoparticles

Forskningsoutput: KonferensbidragKonferensabstractPeer review

Sammanfattning

Adding metal-oxide shell layers is a promising route for improving the performance of metal nanoparticles (NPs) in various applications. However, despite the rapidly growing interest and a significant amount of experimental work on metal@metal-oxide NPs, computational modeling is relatively scarce, particularly on the sintering mechanism, which plays a crucial role in both the synthesis and performance of NPs. It is well known that the primary sintering mechanisms are surface diffusion and grain boundary diffusion in crystalline materials (Zachariah, 1999) and viscous flow in amorphous clusters (Eggersdorfer, 2011). Therefore, the sintering mechanism of metal@metal-oxide NPs gives rise to fundamental scientific questions as they generally exhibit crystalline cores with amorphous shells. Here, we present atomic diffusion and sintering dynamics of metal@metal-oxide NPs investigated using molecular dynamics based on the ReaxFF potentials.
We have investigated three metal@metal-oxide core@shell NPs as model systems: Ni@NiO, Cu@CuO, and Fe@Fe2O3, all of which are actively studied for various catalytic applications. Sintering MD simulations of two core@shell clusters are analysed using an atom- tracking approach together with crystallinity and mean square displacement (MSD) analysis. The main sintering mechanisms are found to be surface and grain-boundary- like diffusion, similar to that of crystalline NPs (Figure 1). Intriguingly, atomic trajectory tracing (Figure 2) reveals that surface diffusion is highly localized and that it is mainly the surface atoms near the contact region that actively participate in the sintering. In other words, contrary to the common understanding of freely moving high mobility surface atoms (Jose-Yacaman, 2005), atoms located away from the contact region remain distant during the early stage of the sintering process.
We expect the sintering mechanism observed in metal@metal-oxide core@shell NPs here to be particularly relevant for small metal nanoclusters as they usually have a thin surface oxide layer. It can also open up promising new directions in designing aerosol NPs via sintering.
Originalspråkengelska
StatusPublished - 2021 sep. 3
EvenemangEuropean Aerosol Conference 2021 - Online
Varaktighet: 2021 aug. 302021 sep. 3
https://eac2021.co.uk

Konferens

KonferensEuropean Aerosol Conference 2021
Förkortad titelEAC21
Period2021/08/302021/09/03
Internetadress

Ämnesklassifikation (UKÄ)

  • Den kondenserade materiens fysik
  • Nanoteknik

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