Influence of Graphene Oxide/Ag Nanoparticle Composites on the Fluorescence Properties of Organic Dyes

Graphene oxide/ Ag nanoparticle (AgGO) composite materials have been proposed for surface enhanced Raman scattering (SERS) detection of fluorescent dye molecules. In this study we examine the role of the different components of the Ag nanoparticle (NP) decorated graphene oxide (GO) composite on the fluorescence quenching properties of three fluorescent dyes; Rhodamine 6G (R6G), Rhodamine B (RhB) and Sulforhodamine 101 (SR101), with emission spanning from approximately 550 nm to 750 nm. The influence of the dye emission properties, spectrum and quantum yield, on the SERS detection on GO and AgGO substrates has been characterized. The AgGO substrate yields large increases in the measured average Raman signal-to-noise ratios for all three dyes, with the greatest enhancements observed for R6G and SR101. Distinct differences in the way in which each dye is influenced by the individual components of the AgGO composite is observed using time-resolved photoluminescence. The fluorescence quenching efficiency on bare GO is largest for R6G, while the fluorescence lifetime of SR101 is most strongly influenced by the adsorption of the Ag NPs. The SERS enhancement on the AgGO composite benefits most from the fluorescence quenching for R6G, while the localized field enhancement due to the Ag NPs is a more significant factor in the increased Raman scattering signal for SR101.