Charge distribution and Fermi level in bimetallic nanoparticles

Nico Holmberg, Kari Laasonen*, Pekka Peljo

*Corresponding author for this work

    Research output: Contribution to journalArticleScientificpeer-review

    30 Citations (Scopus)
    275 Downloads (Pure)

    Abstract

    Upon metal-metal contact, a transfer of electrons will occur between the metals until the Fermi levels in both phases are equal, resulting in a net charge difference across the metal-metal interface. Here, we have examined this contact electrification in bimetallic model systems composed of mixed Au-Ag nanoparticles containing ca. 600 atoms using density functional theory calculations. We present a new model to explain this charge transfer by considering the bimetallic system as a nanocapacitor with a potential difference equal to the work function difference, and with most of the transferred charge located directly at the contact interface. Identical results were obtained by considering surface contacts as well as by employing a continuum model, confirming that this model is general and can be applied to any multimetallic structure regardless of geometry or size (going from nano- to macroscale). Furthermore, the equilibrium Fermi level was found to be strongly dependent on the surface coverage of different metals, enabling the construction of scaling relations. We believe that the charge transfer due to Fermi level equilibration has a profound effect on the catalytic, electrocatalytic and other properties of bimetallic particles. Additionally, bimetallic nanoparticles are expected to have very interesting self-assembly for large superstructures due to the surface charge anisotropy between the two metals.

    Original languageEnglish
    Pages (from-to)2924-2931
    Number of pages8
    JournalPhysical Chemistry Chemical Physics
    Volume18
    Issue number4
    DOIs
    Publication statusPublished - 28 Jan 2016
    MoE publication typeA1 Journal article-refereed

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