Morphological changes of silica shells deposited on gold nanorods: implications for nanoscale photocatalysts

Milan Adelt, Donald A. MacLaren, David J. S. Birch, Yu Chen

Research output: Contribution to journalArticlepeer-review

Abstract

Gold nanorods (GNRs) support strong localized surface plasmon resonances that can be exploited to enhance the fluorescence or catalytic properties of adjacent molecules. Coating GNRs with silica is frequently used to functionalize their surfaces, but full encapsulation limits the ability to control the spatial distribution of molecules and their related reactivity. For example, locating molecules near the ends of GNRs would enable their strong longitudinal plasmon resonance to be exploited, but such selectivity is challenging. So far, studies of anisotropic coating have been limited and the mechanism of the adsorption onto GNRs remains unclear. Here, we systematically investigated the anisotropic coating of the ends of GNRs with silica and the influence of growth conditions on the formation of silica shells. Three types of nanostructures have been observed and their origins are described: fully encapsulated core-shell GNRs, GNRs with only one end coated with silica, and dumbbell-like GNRs (dGNRs) with both ends coated. The study was performed at around room temperature, where the solubility and micellization of the surfactant cetyltrimethylammonium bromide (CTAB) can be tuned to affect the morphology, stability and density of resulting silica shells. Optimized parameters, in combination with an appropriate GNR aspect ratio, are shown to significantly improve the growth yield of dGNRs, which become the dominant product. A protocol for a high yield synthesis of dGNRs was developed, with a maximum yield exceeding 90 %. This study advances our understanding of the growth mechanism of anisotropic coating of GNRs and sheds light on the optimization of site-selective coating processes. The development of anisotropic GNR-based nanostructures for fluorescence/scattering amplifiers will be important in applications such as metal-enhanced fluorescence, surface-enhanced Raman scattering or plasmon-enhanced catalysis.
Original languageEnglish
Pages (from-to)7730-7738
Number of pages9
JournalACS Applied Nano Materials
Volume4
Issue number8
DOIs
Publication statusPublished - 28 Jul 2021

Keywords

  • gold nanorods
  • silica coating
  • morphology of silica shells
  • anisotropic coating
  • formation of silica shells
  • nanoscale photocatalysts

Fingerprint

Dive into the research topics of 'Morphological changes of silica shells deposited on gold nanorods: implications for nanoscale photocatalysts'. Together they form a unique fingerprint.

Cite this