CHARACTERIZATION BY ELECTRON MICROSCOPY OF HYBRIDS
BETWEEN GOLD NANORODS AND CARBON NANOSTRUCTURES
CAIRES, Anderson. J. (1); ALVES, D. C. B (1); VAZ, R. P. (2); FERLAUTO, A. S (1) and
LADEIRA, L. O (1).
(1) Nanomaterials Laboratory, Physics Department – Federal University of Minas
Gerais. (2) Department of Microbiology, Institute of Biological Sciences – Federal
University of Minas Gerais.
E-mail: caires@fisica.ufmg.br
Introduction
Carbon nanostructures such as carbon nanotubes, graphene, and graphene oxide
have emerged in recent years as promising materials for several important applications
due to their physical and chemical properties. Plasmonic nanostructures, such as gold
nanorods, have been widely applied in different fields because of their excellent
optical properties and broad applications. This is due to the phenomenon of localized
surface plasmon resonance of noble metal nanoparticles, which are electromagnetic
modes associated with the oscillation of electrons on their surface due to their
nanoscale dimensions, and influence these metallic nanostructures to behave as
"nanoantennas", amplifying electromagnetic fields around its surface [1]. This leads to
important effects, including the effect SERS (Surface-enhanced Raman spectroscopy), a
highly sensitive technique that is applied to the study of molecules at very low
concentrations or even to single molecules, which has aroused interest in its use for
biosensing [2]. The combination of graphene oxide or carbon nanotubes with gold
nanorods forms a material which combines the chemical properties of the carbon
nanostructures with the electromagnetic enhancement of gold nanorods [3]. In this
work, we report a simple and easy process of hybrid formation between carbon
nanotube or graphene oxide with gold nanorods in situ in their caracterization by
Transmission Electron Microscopy (TEM) and Scanning Electron Microscope (SEM).
Methods
The synthesis of hybrids nanomaterials was accomplished through the
photochemical synthesis of gold nanorods by ultraviolet irradiation. The growth of gold
nanorods occur in regions actively functionalized of multi-wall carbon nanotubes or
graphene oxide forming a hybrid nanomaterial that we use for forming a thin film. The
optical characterization was carried out by UV-VIS-NIR spectroscopy with a 3600
shimadzu spectrophotometer using 10mm path length quartz cuvettes. TEM
characterizations were performed on a TEM TECNAI G2-20, using an accelerating
voltage of 200 kV in Microscopy Center of UFMG. Samples were prepared by drop-
casting from the dispersion onto a TEM grid (200 mesh, Hole carbon). Thin film
characterization was performed in Scanning electron microscope FEI FEG - Quanta 200.
Results
The images of transmission electron microscopy (TEM) shown in Figure 1, depicts
the graphene oxide/Gold Nanorods hybrid obtained by photochemical synthesis. In the
figure 1a, the gold nanorods are supported by graphene oxide sheets, as shown in
figure 1b.
Figura 1 - TEM images of hybrid Gold nanorods-graphene oxide.
Discussion
We have developed a new method for the synthesis of hybrids between carbon
nanostructures and gold nanorods. The process was carried through the
photochemical synthesis of gold nanorods by irradiation ultraviolet light and their
growth in regions actively functionalized. The synthesis shows excellent distribution
and homogeneity of nanorods as characterized by images of transmission electron
microscopy (TEM).
[1] Kyle C. Bantz et al, Phys. Chem. Chem. Phys., 2011,13, 11551-11567.
[2] Huanjun Chen et al, Chem. Soc. Rev., 2013,42, 2679-2724.
[3] Chengzhou Zhu et al, Nanoscale, 2013,5, 10765-10775.
We acknowledge support from CNPq and UFMG Microscopy Center