Chemistry Reference
In-Depth Information
electron transfer from the PyBS to the graphene. Accordingly, we also
observe the transient absorption around 520 nm which we assign to the
graphene radical anion. The decay of the radical cation formed in the
presence of graphene was fast as evidenced from the appearance of
a short-lived component (900 ns) in the decay profile (Fig. 11(b)).
However, the decay of the transient absorption of pure PyBS monitored
at 470 nm (see inset of Fig. 11(b)) shows a long-lived triplet with a
lifetime of 6.17 microseconds. The transient absorption at 520 nm decays
simultaneously with that of the pyrene radical cation indicating that it is
due to the graphene radical anion.
6. DECORATION OF GRAPHENE WITH METAL NANOPARTICLES
Graphene can be decorated with nanoparticles of metals such as Au and
Pt [4,5]. Decoration can be carried out in a single step by the simple
polyol reduction method using chloroplatinic acid (H
2
PtCl
6
), silver
nitrate (AgNO
3
), chloroauric acid (HAuCl
4
) and tetra-chloropalladic
acid (H
2
PdCl
4
) as the metal precursors. On coating with the metal
nanoparticles, there are significant changes in the Raman spectrum of
graphene, exhibiting shifts in the G-band as well as the other bands
(Fig. 12) with variation in the relative intensities of D and 2D bands [4].
Fig. 12. Raman spectra of EG, EG-Ag (Diameter of silver nanoparticles ~ 4 nm), EG-Pt
(Diameter of platinum nanoparticles ~10 nm) and EG-Au (Diameter of gold nanoparticles
~14 nm).
