Subnanometer thermodynamic overlayers on bimetallic nanoparticles

Abstract

Nanoparticle properties are governed by their surfaces, yet their atomic-scale surface structures remain challenging to predict. Here, we report that bimetallic nanoparticles can form a thermodynamically controlled "shell-dimer" architecture in which one metal forms an overlayer only a few atomic layers thick on another. Using Au-Rh as a model system, atomic-resolution imaging and molecular dynamics show that an ultrathin Au overlayer forms on Rh, stabilized by competition among surface, interfacial, and strain energies. Anisotropic strain limits its growth to the subnanometer scale, and changes in surface chemistry can destabilize the overlayer altogether. Across a range of bimetallic nanoparticles, we found that overlayer formation is associated with elemental immiscibility and lattice mismatch. These findings provide a basis for understanding and controlling surface structures in multimetallic nanoparticles.

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BibTeX RIS

BibTeX

@misc{mccandler2026subnanometer,
  title = {{Subnanometer thermodynamic overlayers on bimetallic nanoparticles}},
  author = {Caitlin A. McCandler and Xianzhuo Lao and Jie Liu and Huipu Liu and Kristin A. Persson and Peng-Cheng Chen},
  howpublished = {arXiv},
  year = {2026},
  month = sep,
  doi = {10.48550/arxiv.2609.29971},
  eprint = {2609.29971},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2609.29971},
  note = {CC BY 4.0},
}

RIS

TY  - UNPB
TI  - Subnanometer thermodynamic overlayers on bimetallic nanoparticles
AU  - Caitlin A. McCandler
AU  - Xianzhuo Lao
AU  - Jie Liu
AU  - Huipu Liu
AU  - Kristin A. Persson
AU  - Peng-Cheng Chen
PY  - 2026
DA  - 2026/09/24
PB  - arXiv
DO  - 10.48550/arxiv.2609.29971
UR  - https://arxiv.org/abs/2609.29971
AB  - Nanoparticle properties are governed by their surfaces, yet their atomic-scale surface structures remain challenging to predict. Here, we report that bimetallic nanoparticles can form a thermodynamically controlled "shell-dimer" architecture in which one metal forms an overlayer only a few atomic layers thick on another. Using Au-Rh as a model system, atomic-resolution imaging and molecular dynamics show that an ultrathin Au overlayer forms on Rh, stabilized by competition among surface, interfacial, and strain energies. Anisotropic strain limits its growth to the subnanometer scale, and changes in surface chemistry can destabilize the overlayer altogether. Across a range of bimetallic nanoparticles, we found that overlayer formation is associated with elemental immiscibility and lattice mismatch. These findings provide a basis for understanding and controlling surface structures in multimetallic nanoparticles.
ER  -

Abstract

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