Regulating and Directionally Controlling Electron Emission from Gold Nanorods with Silica Coatings

Fabio Medeghini, Jacob Pettine, Sean M. Meyer, Catherine J. Murphy, David J. Nesbitt

Research output: Contribution to journalArticlepeer-review

Abstract

Dielectric coatings offer a versatile means of manipulating hot carrier emission from nanoplasmonic systems for emerging nanocatalysis and photocathode applications, with uniform coatings acting as regulators and nonuniform coatings providing directional photocurrent control. However, the mechanisms for electron emission through dense and mesoporous silica (SiO2) coatings require further examination. Here, we present a systematic investigation of photoemission from single gold nanorods as a function of dense versus mesoporous silica coating thicknesses. Studies with dense coatings on gold nanostructures clarify the short (∼1 nm) attenuation length responsible for severely reduced transmission through the silica conduction band. By contrast, mesoporous silica is much more transmissive, and a simple geometric model quantitatively recapitulates the electron escape probability through nanoscopic porous channels. Finally, photoelectron velocity map imaging (VMI) studies of nanorods with coating defects verify that photoemission occurs preferentially through the thinner regions, illustrating new opportunities for designing photocurrent distributions on the nanoscale.

Original languageEnglish (US)
Pages (from-to)644-651
Number of pages8
JournalNano letters
Volume22
Issue number2
DOIs
StatePublished - Jan 26 2022

Keywords

  • gold nanorods
  • hot electrons
  • mesoporous silica
  • photoemission spectroscopy
  • single particle

ASJC Scopus subject areas

  • Bioengineering
  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanical Engineering

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