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Revelation of graphene-Au for direct write deposition and characterization.

Bhandari S, Deepa M, Joshi AG, Saxena AP, Srivastava AK - Nanoscale Res Lett (2011)

Bottom Line: Graphene nanosheets were prepared using a modified Hummer's method, and Au-graphene nanocomposites were fabricated by in situ reduction of a gold salt.Scanning helium ion microscopy (HIM) technique was employed to demonstrate direct write deposition on graphene by lettering with gaps down to 7 nm within the chamber of the microscope.Bare graphene and graphene-gold nanocomposites were further characterized in terms of their composition and optical and electrical properties.

View Article: PubMed Central - HTML - PubMed

Affiliation: National Physical Laboratory, Council of Scientific and Industrial Research, Dr, K,S, Krishnan Road, New Delhi, 110 012, India. aks@nplindia.ernet.in.

ABSTRACT
Graphene nanosheets were prepared using a modified Hummer's method, and Au-graphene nanocomposites were fabricated by in situ reduction of a gold salt. The as-produced graphene was characterized by X-ray photoelectron spectroscopy, ultraviolet-visible spectroscopy, scanning electron microscopy, and high-resolution transmission electron microscopy (HR-TEM). In particular, the HR-TEM demonstrated the layered crystallites of graphene with fringe spacing of about 0.32 nm in individual sheets and the ultrafine facetted structure of about 20 to 50 nm of Au particles in graphene composite. Scanning helium ion microscopy (HIM) technique was employed to demonstrate direct write deposition on graphene by lettering with gaps down to 7 nm within the chamber of the microscope. Bare graphene and graphene-gold nanocomposites were further characterized in terms of their composition and optical and electrical properties.

No MeSH data available.


UV-Vis absorption spectra of pure acid-functionalized graphene and Au-graphene nanocomposites. In toluene containing different concentrations of functionalized graphene. Inset shows the magnified view of surface plasmon absorption peaks.
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Figure 1: UV-Vis absorption spectra of pure acid-functionalized graphene and Au-graphene nanocomposites. In toluene containing different concentrations of functionalized graphene. Inset shows the magnified view of surface plasmon absorption peaks.

Mentions: The successful synthesis of graphene and Au nanoparticles decorated graphene was confirmed by ultraviolet-visible (UV-Vis) spectroscopy (Figure 1). The UV-Vis spectrum of graphene in toluene shows two absorption peaks, one at 240 nm corresponding to π-π* transitions of aromatic C-C bonds and the other at 300 nm which is attributable to n→π* transitions of C=O bonds [23]. When Au nanoparticles were decorated onto the graphene, a broad peak in the visible range was observed corresponding to the surface plasmon absorption of Au nanoparticles. In order to study the effect of graphene concentration in the synthesis of Au nanoparticles, we have also synthesized and recorded UV-Vis spectra at three different concentrations of functionalized graphene in the bath. As concentration of graphene was increased, the peak shows a red shift from 528 nm at 0.1 g l-1 to 545 nm at 0.2 and 0.4 g l-1. The quenching in the peak intensity was also observed which is clearly visible in the inset of Figure 1. This is probably attributable to the increase in Au nanoparticle size that further controls the surface plasmon absorption, with increase in the concentration of functionalized graphene [24]. Also, charge transfer from Au nanoparticles to graphene resulted in a decrease in electron density which eventually contributes to the red shift of the surface plasmon absorption [23]. It is highly probable that this charge transfer is playing role in the stability of this nanocomposite.


Revelation of graphene-Au for direct write deposition and characterization.

Bhandari S, Deepa M, Joshi AG, Saxena AP, Srivastava AK - Nanoscale Res Lett (2011)

UV-Vis absorption spectra of pure acid-functionalized graphene and Au-graphene nanocomposites. In toluene containing different concentrations of functionalized graphene. Inset shows the magnified view of surface plasmon absorption peaks.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211841&req=5

Figure 1: UV-Vis absorption spectra of pure acid-functionalized graphene and Au-graphene nanocomposites. In toluene containing different concentrations of functionalized graphene. Inset shows the magnified view of surface plasmon absorption peaks.
Mentions: The successful synthesis of graphene and Au nanoparticles decorated graphene was confirmed by ultraviolet-visible (UV-Vis) spectroscopy (Figure 1). The UV-Vis spectrum of graphene in toluene shows two absorption peaks, one at 240 nm corresponding to π-π* transitions of aromatic C-C bonds and the other at 300 nm which is attributable to n→π* transitions of C=O bonds [23]. When Au nanoparticles were decorated onto the graphene, a broad peak in the visible range was observed corresponding to the surface plasmon absorption of Au nanoparticles. In order to study the effect of graphene concentration in the synthesis of Au nanoparticles, we have also synthesized and recorded UV-Vis spectra at three different concentrations of functionalized graphene in the bath. As concentration of graphene was increased, the peak shows a red shift from 528 nm at 0.1 g l-1 to 545 nm at 0.2 and 0.4 g l-1. The quenching in the peak intensity was also observed which is clearly visible in the inset of Figure 1. This is probably attributable to the increase in Au nanoparticle size that further controls the surface plasmon absorption, with increase in the concentration of functionalized graphene [24]. Also, charge transfer from Au nanoparticles to graphene resulted in a decrease in electron density which eventually contributes to the red shift of the surface plasmon absorption [23]. It is highly probable that this charge transfer is playing role in the stability of this nanocomposite.

Bottom Line: Graphene nanosheets were prepared using a modified Hummer's method, and Au-graphene nanocomposites were fabricated by in situ reduction of a gold salt.Scanning helium ion microscopy (HIM) technique was employed to demonstrate direct write deposition on graphene by lettering with gaps down to 7 nm within the chamber of the microscope.Bare graphene and graphene-gold nanocomposites were further characterized in terms of their composition and optical and electrical properties.

View Article: PubMed Central - HTML - PubMed

Affiliation: National Physical Laboratory, Council of Scientific and Industrial Research, Dr, K,S, Krishnan Road, New Delhi, 110 012, India. aks@nplindia.ernet.in.

ABSTRACT
Graphene nanosheets were prepared using a modified Hummer's method, and Au-graphene nanocomposites were fabricated by in situ reduction of a gold salt. The as-produced graphene was characterized by X-ray photoelectron spectroscopy, ultraviolet-visible spectroscopy, scanning electron microscopy, and high-resolution transmission electron microscopy (HR-TEM). In particular, the HR-TEM demonstrated the layered crystallites of graphene with fringe spacing of about 0.32 nm in individual sheets and the ultrafine facetted structure of about 20 to 50 nm of Au particles in graphene composite. Scanning helium ion microscopy (HIM) technique was employed to demonstrate direct write deposition on graphene by lettering with gaps down to 7 nm within the chamber of the microscope. Bare graphene and graphene-gold nanocomposites were further characterized in terms of their composition and optical and electrical properties.

No MeSH data available.