Au nanoparticle monolayers covered with sol-gel oxide thin films: Optical and morphological study

Enrico Della Gaspera, Matthias Karg, Julia Baldauf, Jacek Jaroslaw Jasieniak, Gianluigi Maggioni, Alessandro Martucci

Research output: Contribution to journalArticleResearchpeer-review

24 Citations (Scopus)

Abstract

In this work, we provide a detailed study of the influence of thermal annealing on submonolayer Au nanoparticle deposited on functionalized surfaces as standalone films and those that are coated with sol-gel NiO and TiO 2 thin films. The systems are characterized through the use of UV-vis absorption, X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), and spectroscopic ellipsometry. The surface plasmon resonance peak of the Au nanoparticles was found to red-shift and increase in intensity with increasing surface coverage, an observation that is directly correlated to the complex refractive index properties of Au nanoparticle layers. The standalone Au nanoparticles sinter at 200 degrees, and a relationship between the optical properties and the annealing temperature is presented. When overcoated with sol-gel metal oxide films (NiO, TiO 2), the optical properties of the Au nanoparticles are strongly affected by the metal oxide, resulting in an intense red shift and broadening of the plasmon band; moreover, the temperature-driven sintering is strongly limited by the metal oxide layer. Optical sensing tests for ethanol vapor are presented as one possible application, showing reversible sensing dynamics and confirming the effect of Au nanoparticles in increasing the sensitivity and in providing a wavelength dependent response, thus confirming the potential use of such materials as optical probes.
Original languageEnglish
Pages (from-to)13739 - 13747
Number of pages9
JournalLangmuir
Volume27
Issue number22
DOIs
Publication statusPublished - 2011
Externally publishedYes

Cite this