Abstract
We describe a comparison study on 3D ensembles of graphene oxide (GO) and metal nanoparticles (silver nanoparticles (AgNPs), gold nanoparticles (GNPs), and gold nanorods (GNRs)) for surface-enhanced Raman scattering (SERS) application. For the first time, GNRs were successfully assembled on the surfaces of GO by means of electrostatic interactions without adding any surfactant. The SERS properties of GO/AgNPs, GO/GNPs, and GO/GNRs were compared using 2-mercaptopyridine (2-Mpy) as probing molecule. We found that GO/AgNPs and GO/GNPs substrates are not suitable for detecting 2-Mpy due to the very strongπ-πstacking interaction between the 2-Mpy molecules andsp2carbon structure of GO. Conversely, the GO/GNRs substrates show ultrahigh SERS activity and sensitivity of 2-Mpy with the detection limit as low as ~10-15 M, which is ~2-3 orders of magnitude higher than that of the corresponding GNRs.
Highlights
Design and construction of novel assembly architectures with individual nanoparticles (NPs) promote the practical application of NPs into functional nano/microdevices [1,2,3,4,5]
For individual noble-metal NPs, due to collective oscillation of conduction band electrons, when they are irradiated at the wavelength of their localized surface plasmon resonance (LSPR) peak, greatly enhanced electric (E) field area will produce in special surface confined locations such as the tips of gold nanorods (GNRs) and gold nanostars [14, 15]
Before the self-assembly, the GNRs were purified by twice centrifugation at 9600 rpm for 15 min to remove the excess CTAB molecules during the synthesis of GNRs
Summary
Design and construction of novel assembly architectures with individual nanoparticles (NPs) promote the practical application of NPs into functional nano/microdevices [1,2,3,4,5]. Ensembles of noble-metal NPs (gold and silver), due to their unique plasmon resonance, have attracted increasing attention in optical waveguides [7], photothermal therapy [8, 9], surface-enhanced Raman scattering (SERS) [10, 11], and so on. Coupled with the ability to tailor the optical properties of each dimer and the unique ability of the nanosheets to conform to complex topographies while maintaining the geometry and integrity of the dimers, the novel nanosheets promise SERS application. Those methods are complex and time-consuming and of high cost. Their SERS properties were compared using 2-mercaptopyridine (2-Mpy) as probing molecule
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