Graphene oxide (GO) was prepared by oxidation of
graphite under acidic conditions, [6] and subsequent reduction
to form graphene (G) in the presence of ionic liquids
in water. [7] The Raman spectra of both G prepared with
1-ethyl-3-methylimidazolium tetrafluoroborate (EMImBF 4 ,
G–EMImBF 4 , see Figure 1) and GO exhibit G-mode and
D-mode peaks, [7] which arise from the vibration of sp 2 -
hybridized carbon atoms in a 2D hexagonal lattice with
dangling bonds in disordered plane terminations, respec-
tively. [8] The high energy G-mode peak of G–EMImBF 4
(1561 cm ?1 ) is more intense and blue-shifted relative to that
of GO (1602 cm ?1 ), thus implying that the disorder of the
graphene rings is suppressed during reduction. The XRD
pattern of GO contains an intense 001 peak that corresponds
to a d spacing of approximately 0.8 nm, [7] which is in
accordance with the layer-to-layer distance estimated from
AFM observations. [7] In contrast, the XRD pattern of
G–EMImBF 4 contains a broad 002 graphitic diffraction
peak, as well as many additional weak diffraction peaks,
hence suggesting the intercalation of EMImBF 4 molecules
into the G. [9] FT-IR measurements on G–EMImBF 4 also
indicate the lack of a carbonyl stretching band (1750 cm ?1 ),
whereas C ? H stretching (2940 cm ?1 ) and deformation
(1410 cm ?1 ) bands in addition to a new band at 1670 cm ?1
appear. The latter band arises from the vibration of the
intercalated imidazolium framework. [7] Thermogravimetric
analysis (TGA) indicates that G–EMImBF 4 contains approx-
imately 22 wt% organic compounds, according to the weight
loss in the temperature range 200–5008 8C. [7]
Graphene oxide (GO) was prepared by oxidation ofgraphite under acidic conditions, [6] and subsequent reductionto form graphene (G) in the presence of ionic liquidsin water. [7] The Raman spectra of both G prepared with1-ethyl-3-methylimidazolium tetrafluoroborate (EMImBF 4 ,G–EMImBF 4 , see Figure 1) and GO exhibit G-mode andD-mode peaks, [7] which arise from the vibration of sp 2 -hybridized carbon atoms in a 2D hexagonal lattice withdangling bonds in disordered plane terminations, respec-tively. [8] The high energy G-mode peak of G–EMImBF 4(1561 cm ?1 ) is more intense and blue-shifted relative to thatof GO (1602 cm ?1 ), thus implying that the disorder of thegraphene rings is suppressed during reduction. The XRDpattern of GO contains an intense 001 peak that correspondsto a d spacing of approximately 0.8 nm, [7] which is inaccordance with the layer-to-layer distance estimated fromAFM observations. [7] In contrast, the XRD pattern ofG–EMImBF 4 contains a broad 002 graphitic diffractionpeak, as well as many additional weak diffraction peaks,hence suggesting the intercalation of EMImBF 4 moleculesinto the G. [9] FT-IR measurements on G–EMImBF 4 alsoindicate the lack of a carbonyl stretching band (1750 cm ?1 ),whereas C ? H stretching (2940 cm ?1 ) and deformation(1410 cm ?1 ) bands in addition to a new band at 1670 cm ?1appear. The latter band arises from the vibration of theintercalated imidazolium framework. [7] Thermogravimetricanalysis (TGA) indicates that G–EMImBF 4 contains approx-imately 22 wt% organic compounds, according to the weightloss in the temperature range 200–5008 8C. [7]
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