1. International Conference on Advanced Materials, Science and Engineering, July 01-04, 2012, Colombo, Sri Lanka
*Corresponding Author’s E-mail: charithabey@slintec.lk, jeewa@kln.ac.lk
Proc. of Int. Conf. Ad. Mater. Sci. & Eng. (ICAMSE), July 01-04, 2012, Colombo, Sri Lanka
Preparation of Titania Intercalated Graphite Oxide
CI Abeywarnaa*
, AR Kumarasinghea
, KDG Fernandoa
, NM Fonsekaa
, WAPJ Premaratnea,b*
a
Sri Lanka Institute of Nano Technology
Lot 14, Zone 1, Biyagama Export Processing Zone, Walgama, Malwana, Sri Lanka
b
Department of Chemistry, University of Kelaniya, Kelaniya, Sri Lanka
ABSTRACT
Sri Lanka is blessed with deposits of vein graphite consisting of a high crystallinity and high purity (>99.5 %) of
graphite found anywhere in the world. Graphite being a lamellar structure that is both electrically and thermally
highly conductive, allows it to be a versatile material for use in hybrid materials and nanocomposites. Graphite
oxide (GO) which has a lamellar structure and is derived from graphite is a promising material for the synthesis of
hybrid materials and nano-composites. Hybrid materials are known to possess exceptional properties compared to
individual material involved in the hybrid structure. Here we report the intercalation of TiO2 nano particles in the d-
spacing of the lamellar structure of exfoliated GO and the measurements of photocatalytic activity of nano TiO2
intercalated GO hybrid material using methyl orange. Hummers’ method is used to oxidize vein graphite to produce
GO and was exfoliated using sonication. Exfoliated GO was then used in-situ/in-solution to intercalate with nano
TiO2 synthesized using titanium oxysulfate. The degradation of methyl orange in the presence of hybrid material
was studied and compared with that of nano-TiO2. Raw materials, intermediate products, and the hybrid material
was analyzed using x-ray diffraction, thermal gravimetric analysis, scanning electron microscopy, and Fourier
transform infrared spectroscopy to observe material characteristics and physical/chemical properties. UV/VIS
spectroscopy was used to measure the effectiveness of the photocatalytic activity in the degradation of methyl
orange of the hybrid material versus lone nano TiO2.
Key words: graphite oxide, titania, nanocomposites, photocatalysis
Ι. Introduction
Over the past years, nano titanium dioxide (TiO2) has attracted attention for its use in photocatalysis [1], solar cells
[2], gas sensors [3], and opto-electronic devices [4] amongst many other areas. Recently, great efforts have been
made to produce carbon/TiO2 composites. Researchers had formed carbon nanotube (CNT)/TiO2 [5] and C60/TiO2
[6] nanocomposite and shown significant enhancement in photocatalytic efficiency in comparison with nano TiO2
alone. According to the researchers several causes of the superior photocatalytic properties of the carbon/TiO2
nanocomposite are due to higher surface area of the composite enabling enhances adsorption of reactants, the
formation of carbon/TiO2 heterojunctions reducing the electron-hole recombination effect, an apparent shift in the
Fermi energy levels enabling the utilization of longer wavelength photons, and the absorption of photon energy by
the bare carbon surfaces which injects electrons into the conduction band of TiO2, triggering a formation of reacting
radicals [5].
Graphite oxide (GO) is a lamellar structure much like its precursor graphite, yet consisting of a larger d-spacing.
This is due to strong oxidation which covalently attaches oxygen containing groups such as carboxyl, hydroxyl and
epoxide [7]. This insertion of oxygen containing groups makes the d-spacing of graphite of 0.335 nm reach values
as high as 1.0 nm depending on the degree of oxidation [8]. Furthermore these oxygen containing groups makes GO
hydrophilic, compared to graphite which is heavily hydrophobic. This makes GO more accessible in the in-situ/in-
solution formation of the nanocomposite.
In this study, the synthesis of GO/TiO2 nanocomposite was carried out at low temperature using GO formed
from ground vein graphite and titanium oxysulfate (TiO(SO4)) as reactants. It is critical to maintain low temperature
synthesis temperature due to the sensitivity of GO to temperatures above 80 °C. The product was then compared for
photocatalytic activity with nano TiO2 commercially available.
ΙΙ. Experimental Procedures
Vein graphite from Bogala (Bogala Graphite, Sri Lanka) was initially ground down to a finer powder using a
Planetary Micro Mill PULVERISETTE 7 premium line nano-grinder for 15 minutes at 1000 rpm in the wet-grinding
mode. The wet-ground vein graphite was then dried in an oven for 12 h. The dried graphite was then packaged in
an air tight container for storage.

2. International Conference on Advanced Materials, Science and Engineering, July 01-04, 2012, Colombo, Sri Lanka
Hummers’ method was used to oxidize vein graphite to produce GO [9]. While maintaining solution
temperature at 0 °C and stirring moderately, 230 mL of concentrated H2SO4 (UniChem, 98% purity) and 10 g of
ground vein graphite was combined. 30 g of KMnO4 was slowly added while maintaining solution temperature
below 20 °C. This mixture was then continued to stir at 35 °C for 2 h. 460 mL of distilled-deionized water (DDW,
made on site) was then added while maintaining 35 °C. 15 minutes later the reaction was terminated by adding 1.5
L of DDW and 25 mL of 30% H2O2. 5mL of 1:10 HCl was added then filtered and washed. Remaining GO slurry
was washed with DIW multiple times until solution pH reached neutral. Then the solution was dried at 60 °C for 18
h. The resulting paper-like dried GO was contained in an air tight container for storage.
Dried GO sheets were then cut and ground by hand into smaller flakes. 1 g of the GO flakes was sonicated in a
NaOH (Fluka Analytical, 99% purity) solution of 0.2 M to get a 2 g/L mixture, while maintaining mixture
temperature at 50 °C. Sonication was continued for 30 minutes. A 180 mL, 1.25 M H2SO4 solution was added to
4.8 g of TOS (Sigma-Aldrich, 29% assay) and that mixture was immediately added to the sonicating GO solution.
Sonication was continued for 15 minutes and was moved to a stirrer and temperature was monitored at 50 °C for 2 h
while stirring. The resulting mixture was then filtered and washed repeatedly until the solution pH reached neutral.
Then the dark precipitate was dried at 60 °C for 18 h. The GO/TiO2 nanocomposite flakes were stored in a cool dry
dark place in an air tight container.
The GO/TiO2 nanocomposite produced was then ground by hand into smaller flakes. These ground flakes and
TiO2 (anatase nano powder – Sigma-Aldrich, <25 nm, 99.7% metals basis) were subjected to UV light irradiation of
methyl orange (MO) as a target to measure photocatalytic performance. 250 mg of both nanocomposite and TiO2
were mixed with two 20 mL solution of 20 mg/L of MO. Each sample, along with a control was subjected to 15
minute intervals of UV exposure. Between each 15 minute exposure, 5 mL of the MO solution was extracted,
centrifuged for 30 minutes at 9000 rpm and the suspended fluid was then measured for absorbance using UV/Vis
spectrophotometry (Shimadzu UV-3600). The absorbance peak (At) at 483 nm was obtained for each sample and
degradation (Dt) was calculated according to the following, where A0 is bare MO absorbance peak value at 483 nm.
( )⁄ (1)
ΙΙΙ. Results
Among the types of graphite available, vein graphite was chosen over flake expanded graphite due to its high purity
and high crystallinity. The vein graphite samples from Bogala also showed a larger d-spacing derived from x-ray
diffraction (XRD – Bruker D8 Focus) analysis. Thermal gravimetric analysis (TGA – TA Instruments SDT Q600)
also shows the stability of vein graphite with a much higher critical decomposition temperature.
After vein graphite was chosen as the raw material for the carbon backbone of the nanocomposite, vein graphite
was ground down to a finer powder using a Marlven Zetasizer Nano ZS. Three 7 g samples of vein graphite were
ground for 5, 10, and 15 minute intervals and was analyzed using scanning electron microscopy (SEM – Hitachi
SU6600) to observe the particle size reduction. By 5 minute grinding time, there appeared to be particles under 10
microns. But with more grinding time the percentile of particles in the <10 micron range increased dramatically.
The number count of particles of >40 microns particle size was reduced as well. The XRD analysis of the ground
vein graphite showed better stacking of the particles in their preferred orientation from the increase in peak
intensities with higher grinding time. This phenomenon is directly due to the reduction of particle size enabling
better packing of particles in the XRD sample cell.
Figure 1 shows the XRD patterns for GO/TiO2 nanocomposite, GO, and vein graphite. Graphite shows typical
high crystallinity at the (002) plane at 26.5 2θ degrees. For GO this (002) plane is shifted to the left to a value of
9.84 2θ degrees, indicating the expansion of the d-spacing. For the GO/TiO2 nanocomposite, the d-spacing has been
reduced due to the shift of the (002) peak towards the right to a value of 11.48 2θ degrees. This shift of d-spacing
being reduced was theorized as the reduction of oxygen containing groups of GO by the TiO2 being present in the
nanocomposite which is confirmed due to the presence of the (100) peak being present. The absence of prominent
TABLE I
Summary of XRD and TGA analysis of the four types of graphite
Type of
Graphite
d –
spacing
(Å)
Decomposition
Start
(°C) Temperature
Critical
Decomposition
(°C) Temperature
Vein 3.364 500 830
Flake 8213 3.360 450 700
Flake 3442 3.356 500 700
Expanded 3.352 510 780

3. International Conference on Advanced Materials, Science and Engineering, July 01-04, 2012, Colombo, Sri Lanka
0 10 20 30 40 50 60 70
(002)
(002)
(002)(002)(002)
(100)
(c)
(b)
(a)Intensity(a.u.)
2 degrees
GO/TiO2
GO
Vein Graphite
TiO2 peaks in the nanocomposite is due to the low percent composition of TiO2 in the hybrid. Using TGA results
(1.98% reminder incombustible at 1000 °C) combined with the energy dispersive x-ray spectroscopy (EDX) results
taken on the remainder of the TGA analysis (in Table II), it was calculated that TiO2 percent composition is
approximately 1% of the whole composite. Therefore the TiO2 peaks are not prominent on the XRD pattern.
Fig. 1 XRD patterns of GO/TiO2, GO, and vein graphite
TABLE II
Summary of the EDX analysis on the remainder of the TGA analysis
Element
Line
Net
Counts
Net Counts
Error
Weight % Weight %
Error
C K 975 +/- 76 39.66 +/- 1.55
O K 366 +/- 40 22.49 +/- 1.23
Ti K 8491 +/- 252 37.81 +/- 0.53
Ti L 174 +/- 84 --- ---
Total --- 100.00 ---
Fourier transform infrared spectroscopy (FTIR) yield a strong peak at 1580 cm-1
for vein graphite. There were
multiple peaks for GO at 1580 cm-1
, 1680 cm-1
, 3400 cm-1
, 1100 cm-1
, and 1400 cm-1
indicating the presence of the
oxygen containing groups added during oxidation. The GO/TiO2 nanocomposite showed few extra peaks with small
intensity in the Raman spectra at 640 cm-1
, 510 cm-1
, and 400 cm-1
.
SEM images in Figure 2 (a) and (b) show vein graphite and GO/TiO2 composite surface respectively. The
unground vein graphite particles show a wide range of particle sizes from 10-50 microns. The growth of TiO2 can
be seen on the composite surface with particle sizes ranging from 100-500 nm.
Fig. 2 SEM images of (a) vein graphite and (b) GO/TiO2 nanocomposite.
Figure 3 shows the UV/Vis spectrum peaks at 483 nm for MO after being exposed to UV light for 30 minutes
with GO/TiO2 composite and TiO2. The control is also shown in the figure for comparison. Similarly at 15, 30, 45,
(a) (b)

4. International Conference on Advanced Materials, Science and Engineering, July 01-04, 2012, Colombo, Sri Lanka
and 60 minute intervals data was gathered and the peak absorbance value at 483 nm was recorded from the UV/Vis
spectrum and plotted degradation % versus time in Figure 4 using equation (1). Since the control does not degrade
that data was removed from the degradation % figure.
Fig. 3 UV/Vis spectrum of MO doped with GO/TiO2,
TiO2, along with control
Fig. 4 Degradation % versus time derived from UV/Vis
analysis
ΙV. Conclusion
The GO/TiO2 nanocomposite was successfully synthesized at low temperature using GO and TOS as initial
reactants. GO was successfully formed using Sri Lankan vein graphite using Hummers’ method. GO was initially
exfoliated using sonication under an OH-
environment. TOS was hydrolyzed in an H+
environment and both
solutions merged for in-situ/in-solution intercalation while sonicating.
The synthesized nanocomposite exhibits much higher efficiency in degrading MO compared to the same weight
of nano-TiO2 alone. At 60 minutes the nanocomposite has degraded >95% of MO while nano-TiO2 has only
degraded 46%. The important factor being that for the same weight of GO/TiO2, there is only 1% equivalent weight
of TiO2; and that the addition of that 1% TiO2 to the lamellar structure of GO enhances the UV aided degradation of
organic material using photocatalysis by a factor of greater than 2. There is an initial acceleration in degradation for
the nanocomposite compared to the TiO2 alone which is very slow to respond to UV degradation.
V. References
[1] M. R. Hoffmann, S. T. Martin, W. Choi, et al. Environmental applications of semiconductor photocatalysis, Chem Rev, 95
(1995) 69-96.
[2] M. Adachi, Y. Murata, J. Takao, et al. Highly efficient dyesensitized solar cells with a titania thin-film electrode composed
of a network structure of single-crystal-like TiO2 nanowires made by the “oriented attachment” mechanism, Jour Am Chem
Soc, 126 (2004) 14943-14949.
[3] K. Zakrzewska, Mixed oxides as gas sensors, Thin Solid Films, 391 (2001) 229-238.
[4] K. Kalyanasundaram, M. Grätzel, Applications of functionalized transition metal complexes in photonic and optoelectronic
devices, Coord Chem Rev, 177 (1998) 347-414.
[5] B. Gao, G. Z. Chen, G. P. Li, Carbon nanotubes/titanium dioxide (CNTs/TiO2) nanocomposites prepared by conventional
and novel surfactant wrapping sol-gel methods exhibiting enhanced photocatalytic activity, Appl Catal B: Environ, 89
(2009) 503-509.
[6] J. Lin, R. Zong, M. Zhou, et al. Photoelectric catalytic degradation of methylene blue by C60-modified TiO2 nanotube array,
Appl Catal B: Environ, 89 (2009) 425-431.
[7] C. Hontoria, A. J. Lopez, J. D. Lopez, et al. Study of oxygen containing groups in a series of graphite oxides: Physical and
chemical characterization, Carbon, 33 (1995) 1585-1592.
[8] H. K. Jeong, Y. P. Lee, R. J. W. E. Lahaye, Evidence of graphitic AB stacking order of graphite oxides, Jour Am Chem Soc,
130 (2008) 1362-1366.
[9] W. S. Hummers, R. E. Offeman, Preparation of graphitic oxide, Jour Am Chem Soc, 80 (1958) 1339-1340.
300 350 400 450 500 550 600
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
(c)
(b)
(a)
Absorbance(a.u.)
Wavelength (nm)
GO/TiO2
TiO2
Control
0 15 30 45 60
0
20
40
60
80
100
GO/TiO2
TiO2
Degradation(%)
Time (min)