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Characterization of nephelium mutabile blume-like structure of carbon nanotubes
prepared from palm oil by CVD method
M. Maryam, M. S. Shamsudin, and M. Rusop
Citation: AIP Conference Proceedings 1877, 030007 (2017);
View online: https://doi.org/10.1063/1.4999863
View Table of Contents: http://aip.scitation.org/toc/apc/1877/1
Published by the American Institute of Physics
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Characterization Of Nephelium Mutabile Blume-Like
Structure Of Carbon Nanotubes Prepared From Palm Oil
By CVD Method
M.Maryam 1, 2, a), M. S. Shamsudin1,3 and M. Rusop2
1
Faculty of Applied Sciences, Universiti Teknologi MARA (Perak),
Kampus Tapah 35400 Tapah Road, Perak, MALAYSIA.
2
NANO-SciTech Centre, Institute Of Science,
Universiti Teknologi MARA, 40450 Shah Alam, Selangor, MALAYSIA.
3
Faculty of Engineering and the Environment, University of Southampton Malaysia Campus (USMC), 79200
Nusajaya, Johor, MALAYSIA.
a)
maryammohd86@gmail.com
Abstract. A new structure of carbon nanotube was produced from the Single furnace Aerosol-assisted Catalytic CVD
(SFAACVD) method using Palm Oil (PO) as the precursor and Ferrocene (Fe) as the catalyst. A nephelium mutabile
blume (rambutan)-like structure of CNTs was found from the black substance collected from the Alumina boat substrate
placed inside the furnace. Temperature of furnace which was heated at 600 oC – 800 oC plays an important role in
determining the formation of structure. The formation rambutan-like structure of CNTs was optimized at 700 oC and the
samples collected were characterized by Field Emission Scanning Electron Microscope (FE-SEM) to obtain the surface
morphologies. Raman Spectroscopy (RS) and Thermogravimetric Analysis (TGA) were then used to further study the
Raman Spectra and purity of samples.
Keywords: CVD, Carbon Nanotubes, Palm Oil
INTRODUCTION
Carbon Nanotubes were found to be very useful in many applications such as energy conversion devices because
unlike the conventional graphite phase, carbon nanostructures possess metallic or semiconductor properties that can
induce catalysis by participating directly in the charge transfer process. Furthermore, the electrochemical properties
of these materials facilitate modulation of their charge transfer properties and aid in the design of catalysts for
hydrogenation, sensors, and fuel cells [1]. Various types of carbon nanostructures were succesfully synthesized in
the form of nanotubes [2], nanocones [3], nanofibers[4], nanoballs[5], nanowires[6] and many more. Methods such
as arc discharge [7], chemical vapor deposition or spray pyrolysis [8], laser ablation and many more were done to
produce these nanotubes. However, in this experiment CVD method was chosen due to it being the most
inexpensive method and have higher probability of producing carbon nanotubes (CNTs) in large scale [9]. It was
also found that variety of carbon nanotubes were formed using metal catalysts and therefore Fe was chosen to be the
metal catalyst [7].
This paper will report on carbon nanotubes which were successfully synthesized using the aerosol-assisted
catalytic CVD technique using palm oil as the precursor, Ferrocene, Fe as the catalyst and Nitrogen, Ni as the carrier
gas. Previous reports and studies done by fellow researchers on CNTs from palm oil shows that by using this natural
bio-hydrocarbon source, not only can we reduce the production cost; it can also be the green alternative for
industrial scale production of CNTs. Fe as a catalyst also have a higher rate in producing higher quality and larger
scale of CNTs. [10-15].
4th International Conference on the Advancement of Materials and Nanotechnology (ICAMN IV 2016)
AIP Conf. Proc. 1877, 030007-1–030007-7; doi: 10.1063/1.4999863
Published by AIP Publishing. 978-0-7354-1557-7/$30.00
030007-1
EXPERIMENTAL PROCEDURE
CNTs were formed by aerosol-assisted catalytic CVD system. This method was based on the pyrolysis of liquid
aerosols containing palm oil as the precursor into a single stage furnace equipped with a quartz tube. Ferrocene was
weighed onto an alumina boat as the substrate. The catalyst was then put in the middle of the furnace and nitrogen
gas was flowed through the tube into a bubbler connected to the fume hood. The precursor source was heated at
50oC using Topas into the reaction furnace of temperature 600 to 1000o C for 1 hour depositing CNTs under
continuous flow of Nitrogen as the carrier gas. Black substance was collected from the wall of quartz tube and
alumina substrate. The powder like sample collected was then characterized by the field emission scanning electron
microscope, FESEM (ZEISS Supra 40VP) operated at 5kV to evaluate the morphologies and diameter of the
sample. Raman spectra was obtained using micro-Raman spectroscopy (Horiba Jobin Yvon-DU420A-OE-325) with
Ar+ ion of wavelength 514.5nm and Thermogravimetric, TGA (Perkin Elmer Pyris 1 TGA) analysis was done to
determine the decomposition temperature and impurities of sample.
RESULTS AND DISCUSSION
FESEM Images
Figure 1 shows the resulting images of samples collected from AASFCVD method at different deposition
temperature of (a) 600 oC, (b) 650 oC, (c) 700 oC, (d) 750 oC and (e) 800 oC. Carbon nanotubes were present at
temperature (a) - (e). Apparently, amorphous carbon was mostly found at temperature 600 oC and rambutan-like
structure of CNTs were found at deposition temperature of 650, 700, 750 and 800 oC with average diameter of
~17.69 nm, ~26.10 nm, ~30.0 nm and ~32.74 nm respectively.
(a)
(b)
(d)
(c)
(e)
FIGURE 1. FESEM images of CNTs from palm oil using aerosol-assisted single furnace catalytic CVD method at deposition
temperature (a) 600 oC, (b) 650 oC, (c) 700 oC, (d) 750 oC, and (e) 800 oC at magnification of 50.0 k X.
030007-2
The average diameter of CNTs produced from this method is ~26.63 nm with smallest diameter at lowest
temperature of 650 oC and biggest diameter at highest deposition temeperature of 800 oC. Based on the observation
from the FESEM images of the samples, it can be said that lower deposition temperature under 650 oC were
insufficient to pyrolyse the precursor and catalyst resulting in low production of CNTs with incomplete formation.
Only few bundles of shorter length CNTs and some a-C were present with bigger diameter. However, as the
deposition temperature increases, the diameter of CNTs also increases.
Raman Spectroscopy Analysis
Raman spectroscopy was done to study the mechanism influence by quality of CNTs/PVA. The Raman spectra
were taken at the same spot for each sample. Table 1 represents the raman peak position, FWHM and intensity ratios
of samples at deposition temperature of 600 to 800 oC and Table 2 represents the radial breathing mode (RBM)
peaks at temperature 750 and 800 oC. The peaks intensity as seen in Fig. 2(a) ranging from ~1349.1-1377.8 cm-1
represented the disordered D line and peaks ranging from ~1579.2-1603.7 cm-1 represented the graphitic G line. The
G’ peak at 2700 cm-1 were also observed in all samples. Small changes in the Raman shift, intensity and FWHM
were observed with the nanotubes produced at different deposition temperature indicating differences in quality of
samples. The ID/IG ratio were calculated to estimate the variation of CNTs quality with precursor temperature.
TABLE 1. Raman peak position, FWHM and intensity ratios of CNTs from aerosol-assisted single furnace
catalytic CVD at temperature 600 to 800 oC.
Samples
600°C
650°C
700°C
750°C
800°C
Peak Position
(cm-1)
FWHM (cm-1)
G
D
G’
G
D
G’
G
D
G’
G
D
G’
1603.7
1368.4
2708.7
1579.2
1349.1
2860.0
1588.7
1363.5
2704.8
1589.2
1377.8
2719.1
95.0
100.0
77.0
61.7
83.6
48.7
37.6
55.0
72.7
126.9
134.1
105.7
G
1600.0
93.4
D
G’
1365.7
2695.5
187.4
106.3
Peak
Integrated
Intensity Ratio of D,
G Bands, ID/IG Ratio
0.91
0.88
0.69
0.92
1.06
TABLE 2. Radial breathing mode (RBM peaks) and SWNTs diameter at temperature 750 and 800 oC by aerosol-assisted single
furnace catalytic cvd.
Samples
RBM peaks, ω (cm-1)
SWNTs diameter (nm)a
800
238.66
1.13
750
232.40
292.84
400.20
1.07
0.85
0.62
d = 248 (cm-1 nm)/ω(cm-1)
030007-3
The results showed a clear trend of decreasing ID/IG ratio as the temperature increased with ratio of 0.91 at
temperature 600 oC, 0.88 at temperature 650 oC and lowest at temperature 700 oC with ratio 0.69. However, the ratio
increased a bit at temperature 750 oC and 800 oC with 0.92 and 1.06 respectively. Smaller ratio (<1.0) indicates that
the CNT sample had a narrower distribution of defects while larger ratio shows broader distribution of defects. This
showed that the quality of CNTs increased as the temperature increased and decreased above temperature 750 oC
indicating that the best quality was obtained at 700 oC. These results correlated with the width of G’ peak at
temperature of 600-800 °C with FWHM values of 77.0, 48.7, 72.7, 105.7, and 106.3 cm-1 which showed a trend of
increasing FWHM values at lower deposition temperature and decreasing FWHM values as the deposition
temperature increased.
G
D
G'
800
Raman Intensity (a.u.)
750
700
650
600
0
500
1000
1500
2000
2500
3000
-1
Raman shift (cm )
(a)
RBM Peaks
800
Raman Intensity (a.u.)
750
700
650
600
100
200
300
400
500
-1
Raman shift (cm )
(b)
FIGURE 2. Microraman spectra of CNTs from palm oil using aerosol-assisted single furnace catalytic CVD method at
different deposition temperature of 600-800 oC with increment rate of 50 oC for (a) multiple first order and second order peaks;
D,G & G‘ and (b) multiple low frequency peaks associated with radial breathing mode (RBM) appeared at deposition
temperature of 750 and 800 oC
The radial breathing mode (RBM) peaks were detected at temperature 800 oC as seen in Fig. 2(b), ranging from
~232.40 cm-1 to 400.20 cm-1 indicating the presence of SWCNT which are represented in Table 2 along with the
calculated diameter of single wall carbon nanotubes (SWCNTs) at deposition temperature of 750 and 800 oC. The
diameter of SWNTs were calculated using d=248(cm-1nm)/ ω (cm-1) corresponding to the tubes diameter in the
range of 0.62 to 1.13 nm. The higher rate of palm oil vaporization at higher temperature promote higher amount of
carbon atoms which accumulates for bigger nanotubes diameter therefore vanishing the RBM peak. Therefore, to
produce rambutan-like structure of CNTs with narrow diameter, larger volume and good quality, the suitable
deposition temperature would be 700 °C.
030007-4
TGA Analysis
To further study the purity of samples, TGA analysis was done and the curves and data are tabulated as below:
TABLE 3. TGA data of CNTs at 600 to 800 oC
Samples
(oC)
Initial weight
loss (%)
Residual weight
loss (%)
600
1.2
90.8
8.0
650
1.0
65.7
33.3
700
1.3
62.8
35.9
6.9
58.8
34.3
2.2
84.1
13.7
750
800
Purity of CNTs
(%)
105
100
95
600
Weight %
90
85
800
80
75
70
650
65
700
60
750
55
0
200
400
600
800
1000
o
Temperature ( C)
FIGURE 3. TGA curves of CNTs from palm oil using aerosol-assisted single furnace catalytic CVD method at deposition
temperature of 600 – 800 oC
Table 3 represented the data calculated from the TGA curve as seen in Figure 3. TGA curve shown in Fig. 3
showed an initial weight loss at temperature around ~89.0 oC to ~450.2 oC which may be caused by the
decomposition of residual hydrocarbon impurities. Significant weight loss were estimated around temperature range
of ~450 to ~680 oC due to the decomposition of CNTs. Remaining percentage of weight loss consists of the Fe
catalyst and nonvolatile elements [14, 15]. It can be said that the highest purity of CNTs is at temperature of 700 oC
with total of 35.9 %.
030007-5
CONCLUSION
It can be concluded that by using the aerosol-assisted souble furnace CVD method, rambutan-like structure of
carbon nanotubes were successfully synthesized at various deposition temperature ranging from 600-800 oC with
increment of 50 oC. As seen from the FESEM image, the CNTs produced were at the smallest diameter and
uniformed distribution at temperature 700 oC. At lower temperature of 600 oC, the temperature was not enough to
completely synthesized the CNTs resulting in shorter length of CNTs with high impurities and abundant amorphous
carbon. However, at higher temperature (650-800 oC), CNTs were present with increased in temperature.The
microraman spectra study further supported these results which showed the presence of single wall, multi wall CNTs
with highest crystallinity and purity of CNTs yield at optimized deposition temperature of 700 oC and average
diameter of ~26.10 nm within the bundles. It also had the lowest I D/IG ratio of 0.69 representing good quality and
high crystallinity of CNTs. This is due to the optimized temperature of CNTs synthesis where the temperature is
high enough to produce a reaction between the catalyst and precursor without damaging the structure compared to a
higher temperature. Lower temperature however produce more amorphous carbon than CNTs.
ACKNOWLEDGMENTS
The authors would like to thank Universiti Teknologi MARA and also Malaysia Ministry of Higher Education
for their support and funding.
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030007-6
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030007-7
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