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Direct growth of coiled carbon nanofibers without nanocatalyst
Accepted Manuscript Direct growth of coiled carbon nanofibers without nanocatalyst
Amit Thakur, Alakesh Manna, Sushant Samir PII: DOI: Reference:
S0925-9635(16)30541-6 doi: 10.1016/j.diamond.2017.02.011 DIAMAT 6820
To appear in:
Diamond & Related Materials
Received date: Revised date: Accepted date:
28 October 2016 27 January 2017 11 February 2017
Please cite this article as: Amit Thakur, Alakesh Manna, Sushant Samir , Direct growth of coiled carbon nanofibers without nanocatalyst. The address for the corresponding author was captured as affiliation for all authors. Please check if appropriate. Diamat(2017), doi: 10.1016/j.diamond.2017.02.011
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Direct Growth of Coiled Carbon nanofibers without nano catalyst
Article Type: Research Paper Corresponding Author: Mr. Amit Thakur, M.Tech
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Corresponding Author's Institution: UIET, Panjab University, India; email: [email protected]
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Order of Authors: Amit Thakur1, M.Tech; Alakesh Manna2, Ph.D.; Sushant Samir3, Ph.D. Assistant Professor, Mechanical Engineering Department, UIET, Panjab University, India;
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Professor, Mechanical Engineering Department, PEC University of Technology, Chandigarh,
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1
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India; 3Associate Professor, Mechanical Engineering Department, PEC University of Technology, Chandigarh, India; email: [email protected], [email protected]
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Abstract
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The paper presents the coiled carbon nanofibers growth on bulk metals without use of nano catalyst on indigenously developed custom build Chemical Vapour Deposition (CVD) set-up. Transition metal and alloys as substrate were investigated for their effect on morphology during
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growth of carbon nanofibers. The application of Inconel proved as a very good substrate for homogenous coiled nanofibers growth. Effects of variation in temperature and gas flow ratio
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were studied on diameter and helix angle of synthesized carbon nanofibers on Inconel as substrate. Experimental results reveal that the range of diameter of carbon nanofibers was 80-150
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nm. Transmission electron microscopy (TEM) analysis shows stacked-cup type structure with amorphous carbon deposits on carbon nanofibers. As the CVD process is very simple and economical, hence, this process can be effectively used for direct growth of carbon nanofibers. 1. Introduction The attractive properties of carbon and its allotropes have been attracting the metallurgist and scientist for extensive research in the area almost two and half decades. Carbon nanotubes, carbon fibers, diamonds and graphene being the most reported allotropes. Carbon filaments with diameter in nanometers are classified as carbon nanotubes (CNTs) or carbon nanofibers (CNFs).
ACCEPTED MANUSCRIPT From review of literature on synthesis of carbon filaments [1–3], its well understood that the transition metal e.g. iron, nickel, cobalt etc. catalyst plays an important role. Chemical vapour deposition (CVD)
being one of the methods of synthesis has been successfully used for
synthesis of CNFs [4]. The CNFs have many potential applications in the fields of manufacturing of sensors, energy storage, nanocomposites etc. because of their interesting inherent properties [5–11]. CNFs are defined as cylindrical graphitic nanostructures with graphite layer arranged in
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various ways. Different types of CNFs are classified as (i) Ribbon CNFs with layers of graphene
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parallel to fiber axis, (ii) Fishbone CNFs with layers of graphene aligned at an angle with fiber
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axis, ( iii) Cup stacked-up CNFs with truncated cones stacked up in direction of the fiber axis and (iv) Spiral helix CNFs with continuous layer of graphene aligned with axis in helical manner
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[12–19].
Different metals had been investigated by various researchers as catalysts for synthesis of carbon
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fibers, most of them being transition metals like iron (Fe), nickel (Ni), cobalt (Co) [18,20–22]. Regular coiled carbon fibers were reported by decomposition of hydrocarbon in presence of Ni
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plate and powder as explained by Motojima et al. [23]. Authors studied on the morphology of the coiled fibers and claimed that they were regular shaped coiled fibers with pitch of ~ 0.1µm,
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length 2-3 mm and extended length 2.8 time of original length. Motojima et al. also studied the effect of oxides, carbides and Ni single crystal on growth of coiled carbon nano fibers (CCNFs).
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Titanium carbide (TiC) was the only metal carbide which was able to synthesize CCNFs in presence of thiophene. For single crystal Ni, the most favored face for graphite precipitation was
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Ni (100) which yield 10% in growth of CCNFs. The floating catalyst methods was used for synthesis of pure CNFs in presence thiophene compound containing Sulphur [24]. Optimum
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amount of thiophene i.e. 0.05-0.55 wt. % was critical for increase in yield of CCNFs as reported by the authors. Qin et al. [24] reported the use of copper nanocrystals as catalyst for growth of helical CNFs with symmetric growth from decomposition of acetylene (C2H2). Authors explained that the change in shape of copper nanocrystal was the reason for mirror-symmetric growth of the CNFs. There are different reports available on the growth of CNFs on metal catalyst particles but no such works investigated on direct growth of CNFs on bulk metals without use of catalyst or support materials. The growth mechanics of CNFs and CCNFs is explained based on Vapour- Liquid-Solid (VLS) mechanism by Wagner and Ellis [25] and the spatial velocity hodograph for extrusion of helical nanotubes and nanofibers proposed by
ACCEPTED MANUSCRIPT Amelinckx et al.[26]. According to VLS mechanism, dissociated hydrocarbon vapour gets chemisorbed on the surface particle and precipitate-out from one of the faces of the particle in the form of graphic tabular structure after super-saturation. The growth become helical in structure if there is any difference in extrusion velocity at the inner and outer edge of the fiber. The reason for disproportionate rate of extrusion is the anisotropic and inhomogeneous catalytic activity, which in turn leads to stress generation in the structure. This stress is relieved with
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addition of pentagon (+ 60o curvature) and heptagons (- 60o curvature), thereby resulting in helix.
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The formation of knee can be possible by joining of two tubules as suggested by Dunlap [27],
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where as a single pair of pentagon and heptagon were sufficient for joining them. From the review of literature, it’s clear that there is no such available published work on effect of
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different bulk metal substrate and gas flow ratio (Ar:C2H2) on morphology during synthesis of CNFs. Keeping in view, the basic aim is to investigate the synthesis of CNFs directly on bulk
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metal substrate without any pretreatment or reducing gas i.e. hydrogen. The effect of temperature and gas flow ratio of Ar:C2H2 were also studied for analysis on the growth of CNFs.
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Characterization techniques such as Scanning electron microscopy (SEM), Transmission electron microscopy (TEM) and Thermo gravimetric analysis (TGA) were used to analyze the effect of
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temperature on synthesized CNFs and results are explained in this research paper.
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2. Experimental procedure and Pilot Experiments 2.1 Chemical vapour deposition (CVD)
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CNFs were synthesized on developed custom built CVD set-up. Figure 1 shows the schematic
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diagram of developed fabricated setup.
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Figure 1 Schematic diagram of the developed CVD setup
To study the effect of metal substrate on synthesis of CNFs, experiments were carried out in total
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gas flow rate of 100 sccm with 60:40 ratio of Ar and C2H2. The pilot experiments were carried out to select the process parameters for further detailed experimental investigation. The substrate
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was placed in the center of rector (Figure 1). A proportional-integral-derivative (PID) controller was used to maintain the heating furnace temperature at 700 oC. One of the thermocouples was
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fitted inside the reactor to measure the temperature of substrate. Temperature difference between inside and outside of the rector was ~ 50 – 55 oC. At the beginning of C2H2 flow reaction
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chamber temperature was raised but after certain interval of time the temperature came back to required temperature setting. The reaction chamber temperature was monitor and controlled
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during synthesis through PID controller. To preheat the carrier and carbon precursor gas, the inlet of gas line was heated to 320 oC with coiled heating element. The flow of gases was
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directed towards metal substrate with the help of alumina tube. The stainless tube is not suitable for this purpose as its choking due to dissociation of hydrocarbon gases. 2.2 Substrate
Transition metal and alloys were selected as substrates for this study. The metals selected for substrates were stainless steel 304 (SS 304), stainless steel 316 (SS 316), Nickel (Ni), and Inconel. The commercially available stainless steel sheets manufactured by Jindal Steel Company, India were purchased and used as substrate. Inconel and Ni were purchased from KM steel, India. The substrates of size 10 x 13 x1 mm were prepared from sheets by wire cut Electric Discharge machining (EDM). The metallic substrates sheets were cleaned and sonicated for 45
ACCEPTED MANUSCRIPT min in acetone to remove dirt and oil from surface. The substrates were placed parallel to the flow of gases. Before use of each individual substrate was weight and recorded for further analysis. Elemental composition of different substrates is given in Table 1. Table 1. Elemental Composition of different substrates
Stainless
Cr
Ni
Mn
Si
0.07
17.55
7.57
1.64
.65
.08
17.34
10.23
1.12
1.42
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Bal.
99.9
Nickle
15.73
76.41
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.38
Bal.
7.07
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Inconel
.80
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Steel 316
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Steel 304 Stainless
Fe
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2.3 Characterization
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The carbon growth on substrate was carefully removed from the reactor after cooling down. Weight of carbon growth was determined from the difference in weight of substrate before and
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after experiments using micro weight balance. All the carbon growth on substrate was analyzed using FESEM for morphological study of carbon deposits. Thermogravametric analysis (TGA)
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was performed at 5 oC / min in air with flow rate 150 ml/min. Some part of the carbon growth with varying weight ranges from 9 to 10 mg was used for TGA analysis. Oxidative stability of
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CNFs was studied for carbon grown at different temperature. Transmission electron microscopy (TEM) was also used to study the structure of CNFs at higher magnifications.
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2.4 Process Parameters and Pilot Experimentation A set of experiments has been conducted during the initial phase to identify the suitable substrate, important parameters and analyze the growth of carbon on substrate utilizing the developed CVD setup. The identified parameters were (a) Temperature, (b) Time, and (c) Ratio of Ar:C2H2, (d) Total flow rate. Table 2 represents the selected parameters and their levels considered for experimentation.
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2
3
4
5
A:Temperature(oC)
600
650
700
750
800
B:Time (min)
5
15
30
45
60
C:Ratio of Ar: C2H2
70:30
60:40
50:50
40:60
30:70
D:Total Flow Rate (sccm)
100
100
100
100
100
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Levels
Table 3 represents the different process parameters for experimental investigation on effect
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different substrates with test results i.e. yields (mg). Here yield is defined as the difference of weight of substrate with carbon growth and pure substrate. From Table 3, it’s clear that the
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substrate Nickel is most effective which gives highest yield as compared to other substrate used for experiments. However, growth of carbon was in the form of straight CNFs (Figure 2 (b)).
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Whereas, growth of carbon on the Inconel substrate was more homogeneous and in the form of coils (Figure 2 (c)), which is acceptable for further use as nanocomposite. This could be
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explained as the activity of various transition metals varies in respect of carbon absorption, the difference in precipitation rate could be responsible for synthesis of helical fibers [26,27].
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Moreover the CNFs on nickel appears as bundle or a group of small diameter CNFs grown together, whereas on Inconel substrate the growth was single coiled nanofibers. Figure 2 show
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the FESEM images when used (a) SS 304 (b) Nickel (c) Inconel and (d) SS 316 as substrates.
Exp. No.
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Table 3 Parameters, setting values, substrates used and test results Temperature (A) oC
Time (B) (min.)
Ratio of Ar: C2H2 (C)
Total Flow Rate(D) (sccm)
Substrate
Yield(mg)
1
700
30
60:40
100
SS 304
185.63
2
700
30
60:40
100
Nickel
304.847
3
700
30
60:40
100
Inconel
289.761
4
700
30
60:40
100
SS 316
278.275
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a)
(b)
c)
d)
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Figure 2 (a) SS 304, (b) Nickel, (c) Inconel, and (d) SS 316 (Inset images show the CNFs in enlarged view of the selected region of interest)
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From Figure 2 (a) and (d), it’s clear that the growth of CNFs on SS 304 and SS 316 were not homogenous. The CNFs on SS 304 and SS 316 are mixture of coiled and straight morphology without homogeneity. The results for Inconel were more homogeneous and majority of the CNFs were coiled with ~150 diameter nm and ~ 25 degree helix angle. 2.5 Detailed Experiments to study the effect of Inconel as Metal Substrate Experiments were carried out based on one-factor-at-a-time variable and other kept constant (Table 4 and 5) to study the effect on growth of carbon nanofibers with Inconel as substrate. Figure 3 (a), (b) and (c) show the growth of CNFs on three different Inconel substrates of
ACCEPTED MANUSCRIPT dimension 10x13x1 mm with variation of growth times 15, 30 and 45 minutes respectively at
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700 oC, 60:40 (Ar:C2H2) and 100 sccm (total flow rate).
b)
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c)
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a)
Figure 3 Vertical growth on surface of Inconel substrate (10x13x1 mm) after (a) 15 min., (b) 30 min., and (c) 45
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min. with other parameters held constant i.e. 700 oC temperature, 60:40 (Ar:C2H2) and 100 sccm (total flow rate)
3. Results and Discussion 3.1 Effect of Temperature on yield and morphology of CNFs The detail experiments were carried out on Inconel substrate under atmospheric pressure. To study the effect of temperature on yield with varying time and temperature, five different set of experiments were carried out at constant 60:40 (Ar:C2H2) gas flow ratio and 100 ml/min gas flow rate for continuous 15, 30, 45 and 60 minutes of CNFs growth. Table 4 represents the effect of temperature on yield, diameter and helix angle of growth CNFs. From Table 4, it is clear that
ACCEPTED MANUSCRIPT the yield and temperature share a liner relationship but as time is increased from 15 to 30 minutes there is sudden rise in amount of CNFs growth. The possible reason could be the time taken by substrate to chemisorb carbon from atmosphere and get supersaturated with carbon. Table 4 Effect of temperature on yield, diameter and helix angle Total Flow
Carbon Growth (mg) after Different
Avg.
Avg. Helix
Ar: C2H2
Rate (D) sccm
Time durations
Diameter
Angle
(nm)
(o)
-
-
(C)
650
60:40
YieldT2
YieldT3
YieldT4
0
0
0
0
100
60:40
100
3
700
60:40
100
4
750
60:40
100
5
800
60:40
100
16.43
31.2
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2
600
YieldT1
65.18
Coiled with 78.43
156.9±1.01
distorted structure
23.76
213.3
340.763
412.54
149.32±2.01
34.6±.30
35.65
226.3
353.97
450.54
80.47±1.03
straight
310.76
362.43
460.54
51.21±.277
straight
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( C)
Ratio of
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Temp.
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Exp.
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*where T1=15 min., T2=30 min., T3=45 min., and T4=60 min.
From the results (table 4), 600 oC was not remarkable for any growth. This may be attributed to
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the size of substrate. Figure 4(a) to (d) show FESEM results at (a) 650 oC, (b) 700 oC, (c) 750 oC, and (d) 800 oC respectively after 30 min. From Figure 4, it’s evident that with increase in
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temperature the helix angle decreases and results in more straight and less number of coiled CNFs growth. One interesting fact is clear from FESEM images that, when experiments were
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carried out at low temperature e.g. 650 oC the growth of coiled CNFs are of single fiber only, but at higher temperatures i.e. 750 oC and 800 oC, the CNFs grows in bundles of four fiber with very less coiled structure. The diameter of individual nanofibers decreases with increase in temperature. At low temperature i.e. 650 oC the growth of nanofibers are regularly coiled and but have distorted structure as compared to fiber growth at higher temperature.
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b)
c) o
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a)
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d) o
o
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Figure 4 FESEM results for (a) 650 C, (b) 700 C, (c) 750 C, and (d) 800 C
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TEM image analysis Figure 5, revels that the structure is cup shaped with thickening of fiber walls which may be due to higher percentage of Ni in Inconel [28]. Table 4 also represents experimental results with variation of time and temperature on CNFs growth diameter and helix
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angle. TGA (Figure 6 (b)) of the samples show a rapid decrease in weight of the sample in particular temperature range. There is increase in this range where the sample is stable with increase in growth temperature. The initial weight loss is attributed to absorbed water vapour which gets evaporated during initial heating of samples. The major weight loss in samples were observed at temperature ranges from 400-600 oC, due to decomposition of amorphous carbon present along with sample (Figure 5).
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Layers of graphite
b)
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a)
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Amorphous carbon
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Graphite layer arrangement in Stacked cup type arrangement
c)
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Figure 5 TEM images for (a) 650 oC, (b) 700 oC, (c) 750 oC, and (d) 800 oC
d)
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min) min) min) min)
10
300 Yield (mg)
Yield (mg)
T650 T700 T750 T800
8
Weight Loss (mg)
400
(15 (30 (45 (60
200
100
6
4
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YieldT1 YieldT2 YieldT3 YieldT4
0 650
700
750
800
100
200
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600
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2 0
Temp. (deg(ooC) C) Temp.
a)
300
400
500
600
Temp.(OC)
b)
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Figure 6 (a) Plot for growth of CNFs on substrate (Yield) vs different growth Temperatures and (b) TGA for different CNFs samples after 30 min. of growth time at different temperatures.
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3.2 Effect of Gas flow ratio on yield and morphology of CNFs
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Gas flow ratio is the ratio between carrier gas and carbon precursor. The effect of gas flow ratio on growth was analyzed based on the acquired results from the experiments carried out at
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constant 700 oC temperature and 100 sccm gas flow rate. Table 5 represents the variation of gas flow ratio with time and test results. From Table 5, it’s evident that the growth i.e. yield
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decreases with increase of Ar in the ratio gas flow, it is because of decrease in amount of carbon present for decomposition. Table 5 also represents the effect the gas flow ratio on CNFs growth
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diameter and helix angle. With decrease of Arin the gas flow ratio, there is increase in yield and average diameter of CNFs over the surface of substrate. It may be due to increase of carbon
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precursor in total gas flow. The effect on average helix angle varies in range of ~ 36-44 temperature.
o
with
700
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Exp.
Gas Flow
Temp.
Total Flow
Carbon Growth (mg) after Different
Avg.
Avg.
No.
Ratio
(oC)
Rate (D) sccm
Time durations
Diameter
Helix
(nm)
Angle (o)
(Ar :C2H2) YieldT1
YieldT2
YieldT3
YieldT4
70:30
700
100
8.53
106
203.54
256.76
110.402±.49
41.6±2.95
2
60:40
700
100
12.6
213.3
339.23
425.92
116.916±.28
42±.91
3
50:50
700
100
20.43
287.2
394.65
136.766±.29
44.4±.97
4
40:60
700
100
34.48
300.2
421.43
460.32
140.512±.43
43.1±2.11
5
30:70
700
100
57.28
338.69
434.79
473.32
139.961±.43
37.6±1.2
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Table 5 Effect of different gas flow ratios on yield, diameter and helix angle
500
145
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Yield300 (mg)
200
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100
0.5
CE
0
1.0 Ar:C2H2 1.5
Average Diameter Avg. Helix Angle
140 135
44
130 42 125 40 120 115
38
110 36 105
2.0
2.5
0.5
1.0
Ar:C2H2 1.5 Flow ratio
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Ar:C2H2
2.0
Figure 7(a) Plot for growth of CNFs on substrate (Yield) vs different gas flow ratios and (b) Effect on Average diameter and helix angle for different Gas flow ratio
a)
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b)
2.5
Avg. Helix Angle (o)
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Yield T1 (15 min)
Average Diameter (nm)
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Yield T1 (15 min) Yield T2 (30 min) Yield T3 (45 min) Yield T4 (60 min)
400
*
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*where T1=15 min., T2=30 min., T3=45 min., and T4=60 min.
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d)
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a)
e) Figure 8 FESM results at gas flow ratio Ar:C2H2(a) 70:30, (b) 60:40, (c) 50:50, (d) 40:60 and (e) 30:70
ACCEPTED MANUSCRIPT Figure 8 shows the FESEM images at different flow ratios with constant temperature (700 oC), total flow rate (100) and time (30 min). The CNFs at 70:30 (Ar: C2H2) ratio was consistently coiled as compared to CNFs with other Ar: C2H2 ratios. 4. Conclusion The different sets of experiments have been carried out utilized chemical vapor deposition
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(CVD) technique on developed setup to study the effect of process parameters on growth of
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coiled carbon nanofibers (CCNFs). The study on growth of CNFs was under taken on different
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substrate. Based on the performance and experimental results on pilot experiments, the detail experiments were carried out on Inconel substrate. When Inconel was used as substrate, it was identified that the homogenous growth of coiled CNFs at temperature ranges from 650 oC to 700
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o
C. With increase in temperature there is decrease in diameter of individual fibers. At high
temperature it was also identified that the diameter of growth CNFs were small but in bundle i.e.
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four smaller nanofibers growing out together. The diameter of nanofibers increases with increase in C2H2 concentration in gas flow ratio, whereas helix angle remained approximately same.
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Large quantities of carbon fibers can be directly grown without any use of nano particles on bulk
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Acknowledgments
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metals thereby decreasing the cost of production and making the process simple.
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Authors acknowledge the Panjab University for supporting university lab. Authors would also
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like to thank Inderjit Singh for FESEM image analysis at IISER, Mohali.
References [1]
R.T.K. Baker, P.S. Harris, R.B. Thomas, R.J. Waite, Formation of filamentous carbon from iron, cobalt and chromium catalyzed decomposition of acetylene, J. Catal. 30 (1973) 86–95. doi:10.1016/0021-9517(73)90055-9.
ACCEPTED MANUSCRIPT [2]
E.L. Evans, J.M. Thomas, P. a. Thrower, P.L. Walker, Growth of filamentary carbon on metallic surfaces during the pyrolysis of methane and acetone, Carbon N. Y. 11 (1973) 441–445. doi:10.1016/0008-6223(73)90302-3.
[3]
R.T.K. Baker, P.S. Harris, J. Henderson, R.B. Thomas, Formation of carbonaceous deposits from the reaction of methane over nickel, Carbon N. Y. 13 (1975) 17–22.
X. Jian, M. Jiang, Z. Zhou, M. Yang, J. Lu, S. Hu, Y. Wang, D. Hui, Preparation of high
IP
[4]
T
doi:10.1016/0008-6223(75)90252-3.
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purity helical carbon nanofibers by the catalytic decomposition of acetylene and their growth mechanism, Carbon N. Y. 48 (2010) 4535–4541.
[5]
US
doi:10.1016/j.carbon.2010.08.035.
Y. Liu, H. Teng, H. Hou, T. You, Nonenzymatic glucose sensor based on renewable
AN
electrospun Ni nanoparticle-loaded carbon nanofiber paste electrode, Biosens. Bioelectron. 24 (2009) 3329–3334. doi:10.1016/j.bios.2009.04.032. J.S. Lee, O.S. Kwon, S.J. Park, E.Y. Park, S.A. You, H. Yoon, L.E.E.E.T. Al, Fabrication
M
[6]
of Ultra fi ne Metal-Oxide- Decorated Carbon Nano fi bers for DMMP Sensor
J. Jang, J. Bae, Carbon nanofiber/polypyrrole nanocable as toxic gas sensor, Sensors
PT
[7]
ED
Application, ACS Nano. 5 (2011) 7992–8001.
Actuators, B Chem. 122 (2007) 7–13. doi:10.1016/j.snb.2006.05.002. L. Ji, X. Zhang, Electrospun carbon nanofibers containing silicon particles as an energy-
CE
[8]
storage medium, Carbon N. Y. 47 (2009) 3219–3226. doi:10.1016/j.carbon.2009.07.039. D.P. Dubal, O. Ayyad, V. Ruiz, P. Gómez-Romero, Hybrid energy storage: the merging of
AC
[9]
battery and supercapacitor chemistries, Chem. Soc. Rev. 44 (2015) 1777–1790. doi:10.1039/C4CS00266K. [10] M.H. Al-Saleh, U. Sundararaj, A review of vapor grown carbon nanofiber/polymer conductive composites, Carbon N. Y. 47 (2009) 2–22. doi:10.1016/j.carbon.2008.09.039. [11] Y. Zhou, F. Pervin, S. Jeelani, P.K. Mallick, Improvement in mechanical properties of carbon fabric-epoxy composite using carbon nanofibers, J. Mater. Process. Technol. 198 (2008) 445–453. doi:10.1016/j.jmatprotec.2007.07.028.
ACCEPTED MANUSCRIPT [12] A. Chambers, C. Park, R.T.K. Baker, N.M. Rodriguez, Hydrogen storage in graphite nanofibers, J. Phys. Chem. B. 102 (1998) 4253–4256. doi:10.1021/jp980114l. [13] A. Chambers, T. Nemes, N.M. Rodriguez, R.T.K. Baker, Catalytic Behavior of Graphite Nanofiber Supported Nickel Particles . 1 . Comparison with Other Support Media, J. Phys. Chem. B. 102 (1998) 5168–5177. doi:10.1021/jp973462g.
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[14] C.A. Bessel, K. Laubernds, N.M. Rodriguez, R.T.K. Baker, Graphite nanofibers as an
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electrode for fuel cell applications, J. Phys. Chem. B. 105 (2001) 1115–1118.
CR
doi:10.1021/jp003280d.
[15] C. Pham-Huu, N. Keller, G. Ehret, L.J. Charbonniere, R. Ziessel, M.J. Ledoux, Carbon
US
nanofiber supported palladium catalyst for liquid-phase reactions an active and selective catalyst for hydrogenation of cinnamaldehyde into hydrocinnamaldehyde, J. Mol. Catal. A
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Chem. 170 (2001) 155–163. doi:10.1016/S1381-1169(01)00055-3. [16] H. Terrones, T. Hayashi, M. Muñoz-Navia, M. Terrones, Y.A. Kim, N. Grobert, R.
M
Kamalakaran, J. Dorantes-Dávila, R. Escudero, M.S. Dresselhaus, M. Endo, Graphitic cones in palladium catalysed carbon nanofibres, Chem. Phys. Lett. 343 (2001) 241–250.
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doi:10.1016/S0009-2614(01)00718-7.
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[17] C.W. Huang, Y.Y. Li, In situ synthesis of platelet graphite nanofibers from thermal decomposition of poly(ethylene glycol), J. Phys. Chem. B. 110 (2006) 23242–23246.
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doi:10.1021/jp064736f.
[18] M. Weisenberger, I. Martin-Gullon, J. Vera-Agullo, H. Varela-Rizo, C. Merino, R.
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Andrews, D. Qian, T. Rantell, The effect of graphitization temperature on the structure of helical-ribbon carbon nanofibers, Carbon N. Y. 47 (2009) 2211–2218. doi:10.1016/j.carbon.2009.03.070. [19] M. Endo, Y.A. Kim, T. Hayashi, Y. Fukai, K. Oshida, M. Terrones, T. Yanagisawa, S. Higaki, M.S. Dresselhaus, Structural characterization of cup-stacked-type nanofibers with an entirely hollow core, Appl. Phys. Lett. 80 (2002) 1267–1269. doi:10.1063/1.1450264. [20] W. Huang, X. Zhang, J. Tu, F. Kong, Y. Ning, J. Xu, G. Van Tendeloo, Synthesis and characterization of graphite nanofibers deposited on nickel foams, Phys. Chem. Chem.
ACCEPTED MANUSCRIPT Phys. 4 (2002) 5325–5329. doi:10.1039/b206072h. [21] Y. Suda, K. Maruyama, T. Iida, H. Takikawa, H. Ue, K. Shimizu, Y. Umeda, High-Yield Synthesis of Helical Carbon Nanofibers Using Iron Oxide Fine Powder as a Catalyst, Crystals. 5 (2015) 47–60. doi:10.3390/cryst5010047. [22] C. Singh, T. Quested, C.B. Boothroyd, I. a Kinloch, A.I. Abou-kandil, A.H. Windle, P.
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Thomas, Synthesis and Characterization of Carbon Nanofibers Produced by the Floating
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Catalyst Method Synthesis and Characterization of Carbon Nanofibers Produced by the
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Floating Catalyst Method, Society. (2002) 10915–10922. doi:10.1021/jp026159a. [23] S. Motojima, M. Kawaguchi, K. Nozaki, H. Iwanaga, Growth of regularly coiled carbon
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filaments by Ni catalyzed pyrolysis of acetylene, and their morphology and extension characteristics, Appl. Phys. Lett. 56 (1990) 321–323. doi:10.1063/1.102816.
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[24] Y.Y. Fan, H.M. Cheng, Y.L. Wei, G. Su, Z.H. Shen, Influence of preparation parameters on the mass production of vapor-grown carbon nanofibers, Carbon N. Y. 38 (2000) 789–
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795. doi:10.1016/S0008-6223(99)00178-5.
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[25] R.S. Wagner, W.C. Ellis, Vapor-liquid-solid mechanism of single crystal growth, Appl. Phys. Lett. 4 (1964) 89–90. doi:10.1063/1.1753975.
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[26] N.B.J. Amelinckx, S., Zhang B. X., Bernaetrs D., Zhang F. X., Ivanov V., A formation
635–639.
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mechanism for catalytically grown helix-shaped graphite nanotubes, Science. 265 (1994)
[27] W. Qian, T. Liu, Z. Wang, H. Yu, Z. Li, F. Wei, G. Luo, Effect of adding nickel to iron –
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alumina catalysts on the morphology of as-grown carbon nanotubes, Carbon N. Y. 41 (2003) 2487–2493. [28] I. Martin-Gullon, J. Vera, J.A. Conesa, J.L. González, C. Merino, Differences between carbon nanofibers produced using Fe and Ni catalysts in a floating catalyst reactor, Carbon N. Y. 44 (2006) 1572–1580. doi:10.1016/j.carbon.2005.12.027.
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C2H2
Detailed experiment and analysis of growth on Inconel
SS 316 Inconel
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Ar
TEM
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Nickel
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CVD with different metals as substrate
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Carbon nanofibers
SS 304
SEM
ACCEPTED MANUSCRIPT Highlights of present work
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Growth of carbon nanofibers directly on metal substrate using indigenously developed chemical vapour deposition setup. Effect of different transition metal and alloys investigated. Growth of coiled carbon nanofibers on Inconel. Effect of variation in temperature and ratio of carrier gas to precursor gas on morphology studied and reported.
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Amit Thakur, Alakesh Manna, Sushant Samir PII: DOI: Reference:
S0925-9635(16)30541-6 doi: 10.1016/j.diamond.2017.02.011 DIAMAT 6820
To appear in:
Diamond & Related Materials
Received date: Revised date: Accepted date:
28 October 2016 27 January 2017 11 February 2017
Please cite this article as: Amit Thakur, Alakesh Manna, Sushant Samir , Direct growth of coiled carbon nanofibers without nanocatalyst. The address for the corresponding author was captured as affiliation for all authors. Please check if appropriate. Diamat(2017), doi: 10.1016/j.diamond.2017.02.011
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Direct Growth of Coiled Carbon nanofibers without nano catalyst
Article Type: Research Paper Corresponding Author: Mr. Amit Thakur, M.Tech
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Corresponding Author's Institution: UIET, Panjab University, India; email: [email protected]
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Order of Authors: Amit Thakur1, M.Tech; Alakesh Manna2, Ph.D.; Sushant Samir3, Ph.D. Assistant Professor, Mechanical Engineering Department, UIET, Panjab University, India;
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Professor, Mechanical Engineering Department, PEC University of Technology, Chandigarh,
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1
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India; 3Associate Professor, Mechanical Engineering Department, PEC University of Technology, Chandigarh, India; email: [email protected], [email protected]
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Abstract
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The paper presents the coiled carbon nanofibers growth on bulk metals without use of nano catalyst on indigenously developed custom build Chemical Vapour Deposition (CVD) set-up. Transition metal and alloys as substrate were investigated for their effect on morphology during
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growth of carbon nanofibers. The application of Inconel proved as a very good substrate for homogenous coiled nanofibers growth. Effects of variation in temperature and gas flow ratio
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were studied on diameter and helix angle of synthesized carbon nanofibers on Inconel as substrate. Experimental results reveal that the range of diameter of carbon nanofibers was 80-150
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nm. Transmission electron microscopy (TEM) analysis shows stacked-cup type structure with amorphous carbon deposits on carbon nanofibers. As the CVD process is very simple and economical, hence, this process can be effectively used for direct growth of carbon nanofibers. 1. Introduction The attractive properties of carbon and its allotropes have been attracting the metallurgist and scientist for extensive research in the area almost two and half decades. Carbon nanotubes, carbon fibers, diamonds and graphene being the most reported allotropes. Carbon filaments with diameter in nanometers are classified as carbon nanotubes (CNTs) or carbon nanofibers (CNFs).
ACCEPTED MANUSCRIPT From review of literature on synthesis of carbon filaments [1–3], its well understood that the transition metal e.g. iron, nickel, cobalt etc. catalyst plays an important role. Chemical vapour deposition (CVD)
being one of the methods of synthesis has been successfully used for
synthesis of CNFs [4]. The CNFs have many potential applications in the fields of manufacturing of sensors, energy storage, nanocomposites etc. because of their interesting inherent properties [5–11]. CNFs are defined as cylindrical graphitic nanostructures with graphite layer arranged in
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various ways. Different types of CNFs are classified as (i) Ribbon CNFs with layers of graphene
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parallel to fiber axis, (ii) Fishbone CNFs with layers of graphene aligned at an angle with fiber
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axis, ( iii) Cup stacked-up CNFs with truncated cones stacked up in direction of the fiber axis and (iv) Spiral helix CNFs with continuous layer of graphene aligned with axis in helical manner
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[12–19].
Different metals had been investigated by various researchers as catalysts for synthesis of carbon
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fibers, most of them being transition metals like iron (Fe), nickel (Ni), cobalt (Co) [18,20–22]. Regular coiled carbon fibers were reported by decomposition of hydrocarbon in presence of Ni
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plate and powder as explained by Motojima et al. [23]. Authors studied on the morphology of the coiled fibers and claimed that they were regular shaped coiled fibers with pitch of ~ 0.1µm,
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length 2-3 mm and extended length 2.8 time of original length. Motojima et al. also studied the effect of oxides, carbides and Ni single crystal on growth of coiled carbon nano fibers (CCNFs).
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Titanium carbide (TiC) was the only metal carbide which was able to synthesize CCNFs in presence of thiophene. For single crystal Ni, the most favored face for graphite precipitation was
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Ni (100) which yield 10% in growth of CCNFs. The floating catalyst methods was used for synthesis of pure CNFs in presence thiophene compound containing Sulphur [24]. Optimum
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amount of thiophene i.e. 0.05-0.55 wt. % was critical for increase in yield of CCNFs as reported by the authors. Qin et al. [24] reported the use of copper nanocrystals as catalyst for growth of helical CNFs with symmetric growth from decomposition of acetylene (C2H2). Authors explained that the change in shape of copper nanocrystal was the reason for mirror-symmetric growth of the CNFs. There are different reports available on the growth of CNFs on metal catalyst particles but no such works investigated on direct growth of CNFs on bulk metals without use of catalyst or support materials. The growth mechanics of CNFs and CCNFs is explained based on Vapour- Liquid-Solid (VLS) mechanism by Wagner and Ellis [25] and the spatial velocity hodograph for extrusion of helical nanotubes and nanofibers proposed by
ACCEPTED MANUSCRIPT Amelinckx et al.[26]. According to VLS mechanism, dissociated hydrocarbon vapour gets chemisorbed on the surface particle and precipitate-out from one of the faces of the particle in the form of graphic tabular structure after super-saturation. The growth become helical in structure if there is any difference in extrusion velocity at the inner and outer edge of the fiber. The reason for disproportionate rate of extrusion is the anisotropic and inhomogeneous catalytic activity, which in turn leads to stress generation in the structure. This stress is relieved with
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addition of pentagon (+ 60o curvature) and heptagons (- 60o curvature), thereby resulting in helix.
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The formation of knee can be possible by joining of two tubules as suggested by Dunlap [27],
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where as a single pair of pentagon and heptagon were sufficient for joining them. From the review of literature, it’s clear that there is no such available published work on effect of
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different bulk metal substrate and gas flow ratio (Ar:C2H2) on morphology during synthesis of CNFs. Keeping in view, the basic aim is to investigate the synthesis of CNFs directly on bulk
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metal substrate without any pretreatment or reducing gas i.e. hydrogen. The effect of temperature and gas flow ratio of Ar:C2H2 were also studied for analysis on the growth of CNFs.
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Characterization techniques such as Scanning electron microscopy (SEM), Transmission electron microscopy (TEM) and Thermo gravimetric analysis (TGA) were used to analyze the effect of
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temperature on synthesized CNFs and results are explained in this research paper.
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2. Experimental procedure and Pilot Experiments 2.1 Chemical vapour deposition (CVD)
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CNFs were synthesized on developed custom built CVD set-up. Figure 1 shows the schematic
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diagram of developed fabricated setup.
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Figure 1 Schematic diagram of the developed CVD setup
To study the effect of metal substrate on synthesis of CNFs, experiments were carried out in total
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gas flow rate of 100 sccm with 60:40 ratio of Ar and C2H2. The pilot experiments were carried out to select the process parameters for further detailed experimental investigation. The substrate
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was placed in the center of rector (Figure 1). A proportional-integral-derivative (PID) controller was used to maintain the heating furnace temperature at 700 oC. One of the thermocouples was
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fitted inside the reactor to measure the temperature of substrate. Temperature difference between inside and outside of the rector was ~ 50 – 55 oC. At the beginning of C2H2 flow reaction
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chamber temperature was raised but after certain interval of time the temperature came back to required temperature setting. The reaction chamber temperature was monitor and controlled
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during synthesis through PID controller. To preheat the carrier and carbon precursor gas, the inlet of gas line was heated to 320 oC with coiled heating element. The flow of gases was
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directed towards metal substrate with the help of alumina tube. The stainless tube is not suitable for this purpose as its choking due to dissociation of hydrocarbon gases. 2.2 Substrate
Transition metal and alloys were selected as substrates for this study. The metals selected for substrates were stainless steel 304 (SS 304), stainless steel 316 (SS 316), Nickel (Ni), and Inconel. The commercially available stainless steel sheets manufactured by Jindal Steel Company, India were purchased and used as substrate. Inconel and Ni were purchased from KM steel, India. The substrates of size 10 x 13 x1 mm were prepared from sheets by wire cut Electric Discharge machining (EDM). The metallic substrates sheets were cleaned and sonicated for 45
ACCEPTED MANUSCRIPT min in acetone to remove dirt and oil from surface. The substrates were placed parallel to the flow of gases. Before use of each individual substrate was weight and recorded for further analysis. Elemental composition of different substrates is given in Table 1. Table 1. Elemental Composition of different substrates
Stainless
Cr
Ni
Mn
Si
0.07
17.55
7.57
1.64
.65
.08
17.34
10.23
1.12
1.42
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Bal.
99.9
Nickle
15.73
76.41
.41
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.38
Bal.
7.07
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Inconel
.80
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Steel 316
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Steel 304 Stainless
Fe
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2.3 Characterization
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The carbon growth on substrate was carefully removed from the reactor after cooling down. Weight of carbon growth was determined from the difference in weight of substrate before and
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after experiments using micro weight balance. All the carbon growth on substrate was analyzed using FESEM for morphological study of carbon deposits. Thermogravametric analysis (TGA)
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was performed at 5 oC / min in air with flow rate 150 ml/min. Some part of the carbon growth with varying weight ranges from 9 to 10 mg was used for TGA analysis. Oxidative stability of
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CNFs was studied for carbon grown at different temperature. Transmission electron microscopy (TEM) was also used to study the structure of CNFs at higher magnifications.
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2.4 Process Parameters and Pilot Experimentation A set of experiments has been conducted during the initial phase to identify the suitable substrate, important parameters and analyze the growth of carbon on substrate utilizing the developed CVD setup. The identified parameters were (a) Temperature, (b) Time, and (c) Ratio of Ar:C2H2, (d) Total flow rate. Table 2 represents the selected parameters and their levels considered for experimentation.
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2
3
4
5
A:Temperature(oC)
600
650
700
750
800
B:Time (min)
5
15
30
45
60
C:Ratio of Ar: C2H2
70:30
60:40
50:50
40:60
30:70
D:Total Flow Rate (sccm)
100
100
100
100
100
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Levels
Table 3 represents the different process parameters for experimental investigation on effect
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different substrates with test results i.e. yields (mg). Here yield is defined as the difference of weight of substrate with carbon growth and pure substrate. From Table 3, it’s clear that the
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substrate Nickel is most effective which gives highest yield as compared to other substrate used for experiments. However, growth of carbon was in the form of straight CNFs (Figure 2 (b)).
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Whereas, growth of carbon on the Inconel substrate was more homogeneous and in the form of coils (Figure 2 (c)), which is acceptable for further use as nanocomposite. This could be
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explained as the activity of various transition metals varies in respect of carbon absorption, the difference in precipitation rate could be responsible for synthesis of helical fibers [26,27].
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Moreover the CNFs on nickel appears as bundle or a group of small diameter CNFs grown together, whereas on Inconel substrate the growth was single coiled nanofibers. Figure 2 show
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the FESEM images when used (a) SS 304 (b) Nickel (c) Inconel and (d) SS 316 as substrates.
Exp. No.
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Table 3 Parameters, setting values, substrates used and test results Temperature (A) oC
Time (B) (min.)
Ratio of Ar: C2H2 (C)
Total Flow Rate(D) (sccm)
Substrate
Yield(mg)
1
700
30
60:40
100
SS 304
185.63
2
700
30
60:40
100
Nickel
304.847
3
700
30
60:40
100
Inconel
289.761
4
700
30
60:40
100
SS 316
278.275
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(b)
c)
d)
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Figure 2 (a) SS 304, (b) Nickel, (c) Inconel, and (d) SS 316 (Inset images show the CNFs in enlarged view of the selected region of interest)
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From Figure 2 (a) and (d), it’s clear that the growth of CNFs on SS 304 and SS 316 were not homogenous. The CNFs on SS 304 and SS 316 are mixture of coiled and straight morphology without homogeneity. The results for Inconel were more homogeneous and majority of the CNFs were coiled with ~150 diameter nm and ~ 25 degree helix angle. 2.5 Detailed Experiments to study the effect of Inconel as Metal Substrate Experiments were carried out based on one-factor-at-a-time variable and other kept constant (Table 4 and 5) to study the effect on growth of carbon nanofibers with Inconel as substrate. Figure 3 (a), (b) and (c) show the growth of CNFs on three different Inconel substrates of
ACCEPTED MANUSCRIPT dimension 10x13x1 mm with variation of growth times 15, 30 and 45 minutes respectively at
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700 oC, 60:40 (Ar:C2H2) and 100 sccm (total flow rate).
b)
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c)
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a)
Figure 3 Vertical growth on surface of Inconel substrate (10x13x1 mm) after (a) 15 min., (b) 30 min., and (c) 45
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min. with other parameters held constant i.e. 700 oC temperature, 60:40 (Ar:C2H2) and 100 sccm (total flow rate)
3. Results and Discussion 3.1 Effect of Temperature on yield and morphology of CNFs The detail experiments were carried out on Inconel substrate under atmospheric pressure. To study the effect of temperature on yield with varying time and temperature, five different set of experiments were carried out at constant 60:40 (Ar:C2H2) gas flow ratio and 100 ml/min gas flow rate for continuous 15, 30, 45 and 60 minutes of CNFs growth. Table 4 represents the effect of temperature on yield, diameter and helix angle of growth CNFs. From Table 4, it is clear that
ACCEPTED MANUSCRIPT the yield and temperature share a liner relationship but as time is increased from 15 to 30 minutes there is sudden rise in amount of CNFs growth. The possible reason could be the time taken by substrate to chemisorb carbon from atmosphere and get supersaturated with carbon. Table 4 Effect of temperature on yield, diameter and helix angle Total Flow
Carbon Growth (mg) after Different
Avg.
Avg. Helix
Ar: C2H2
Rate (D) sccm
Time durations
Diameter
Angle
(nm)
(o)
-
-
(C)
650
60:40
YieldT2
YieldT3
YieldT4
0
0
0
0
100
60:40
100
3
700
60:40
100
4
750
60:40
100
5
800
60:40
100
16.43
31.2
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2
600
YieldT1
65.18
Coiled with 78.43
156.9±1.01
distorted structure
23.76
213.3
340.763
412.54
149.32±2.01
34.6±.30
35.65
226.3
353.97
450.54
80.47±1.03
straight
310.76
362.43
460.54
51.21±.277
straight
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Ratio of
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Temp.
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Exp.
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*where T1=15 min., T2=30 min., T3=45 min., and T4=60 min.
From the results (table 4), 600 oC was not remarkable for any growth. This may be attributed to
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the size of substrate. Figure 4(a) to (d) show FESEM results at (a) 650 oC, (b) 700 oC, (c) 750 oC, and (d) 800 oC respectively after 30 min. From Figure 4, it’s evident that with increase in
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temperature the helix angle decreases and results in more straight and less number of coiled CNFs growth. One interesting fact is clear from FESEM images that, when experiments were
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carried out at low temperature e.g. 650 oC the growth of coiled CNFs are of single fiber only, but at higher temperatures i.e. 750 oC and 800 oC, the CNFs grows in bundles of four fiber with very less coiled structure. The diameter of individual nanofibers decreases with increase in temperature. At low temperature i.e. 650 oC the growth of nanofibers are regularly coiled and but have distorted structure as compared to fiber growth at higher temperature.
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b)
c) o
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d) o
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Figure 4 FESEM results for (a) 650 C, (b) 700 C, (c) 750 C, and (d) 800 C
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TEM image analysis Figure 5, revels that the structure is cup shaped with thickening of fiber walls which may be due to higher percentage of Ni in Inconel [28]. Table 4 also represents experimental results with variation of time and temperature on CNFs growth diameter and helix
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angle. TGA (Figure 6 (b)) of the samples show a rapid decrease in weight of the sample in particular temperature range. There is increase in this range where the sample is stable with increase in growth temperature. The initial weight loss is attributed to absorbed water vapour which gets evaporated during initial heating of samples. The major weight loss in samples were observed at temperature ranges from 400-600 oC, due to decomposition of amorphous carbon present along with sample (Figure 5).
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Layers of graphite
b)
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a)
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Amorphous carbon
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Graphite layer arrangement in Stacked cup type arrangement
c)
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Figure 5 TEM images for (a) 650 oC, (b) 700 oC, (c) 750 oC, and (d) 800 oC
d)
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min) min) min) min)
10
300 Yield (mg)
Yield (mg)
T650 T700 T750 T800
8
Weight Loss (mg)
400
(15 (30 (45 (60
200
100
6
4
T
YieldT1 YieldT2 YieldT3 YieldT4
0 650
700
750
800
100
200
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600
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2 0
Temp. (deg(ooC) C) Temp.
a)
300
400
500
600
Temp.(OC)
b)
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Figure 6 (a) Plot for growth of CNFs on substrate (Yield) vs different growth Temperatures and (b) TGA for different CNFs samples after 30 min. of growth time at different temperatures.
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3.2 Effect of Gas flow ratio on yield and morphology of CNFs
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Gas flow ratio is the ratio between carrier gas and carbon precursor. The effect of gas flow ratio on growth was analyzed based on the acquired results from the experiments carried out at
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constant 700 oC temperature and 100 sccm gas flow rate. Table 5 represents the variation of gas flow ratio with time and test results. From Table 5, it’s evident that the growth i.e. yield
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decreases with increase of Ar in the ratio gas flow, it is because of decrease in amount of carbon present for decomposition. Table 5 also represents the effect the gas flow ratio on CNFs growth
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diameter and helix angle. With decrease of Arin the gas flow ratio, there is increase in yield and average diameter of CNFs over the surface of substrate. It may be due to increase of carbon
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precursor in total gas flow. The effect on average helix angle varies in range of ~ 36-44 temperature.
o
with
700
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Exp.
Gas Flow
Temp.
Total Flow
Carbon Growth (mg) after Different
Avg.
Avg.
No.
Ratio
(oC)
Rate (D) sccm
Time durations
Diameter
Helix
(nm)
Angle (o)
(Ar :C2H2) YieldT1
YieldT2
YieldT3
YieldT4
70:30
700
100
8.53
106
203.54
256.76
110.402±.49
41.6±2.95
2
60:40
700
100
12.6
213.3
339.23
425.92
116.916±.28
42±.91
3
50:50
700
100
20.43
287.2
394.65
136.766±.29
44.4±.97
4
40:60
700
100
34.48
300.2
421.43
460.32
140.512±.43
43.1±2.11
5
30:70
700
100
57.28
338.69
434.79
473.32
139.961±.43
37.6±1.2
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Table 5 Effect of different gas flow ratios on yield, diameter and helix angle
500
145
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Yield300 (mg)
200
PT
100
0.5
CE
0
1.0 Ar:C2H2 1.5
Average Diameter Avg. Helix Angle
140 135
44
130 42 125 40 120 115
38
110 36 105
2.0
2.5
0.5
1.0
Ar:C2H2 1.5 Flow ratio
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Ar:C2H2
2.0
Figure 7(a) Plot for growth of CNFs on substrate (Yield) vs different gas flow ratios and (b) Effect on Average diameter and helix angle for different Gas flow ratio
a)
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b)
2.5
Avg. Helix Angle (o)
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Yield T1 (15 min)
Average Diameter (nm)
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Yield T1 (15 min) Yield T2 (30 min) Yield T3 (45 min) Yield T4 (60 min)
400
*
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*where T1=15 min., T2=30 min., T3=45 min., and T4=60 min.
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d)
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e) Figure 8 FESM results at gas flow ratio Ar:C2H2(a) 70:30, (b) 60:40, (c) 50:50, (d) 40:60 and (e) 30:70
ACCEPTED MANUSCRIPT Figure 8 shows the FESEM images at different flow ratios with constant temperature (700 oC), total flow rate (100) and time (30 min). The CNFs at 70:30 (Ar: C2H2) ratio was consistently coiled as compared to CNFs with other Ar: C2H2 ratios. 4. Conclusion The different sets of experiments have been carried out utilized chemical vapor deposition
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(CVD) technique on developed setup to study the effect of process parameters on growth of
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coiled carbon nanofibers (CCNFs). The study on growth of CNFs was under taken on different
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substrate. Based on the performance and experimental results on pilot experiments, the detail experiments were carried out on Inconel substrate. When Inconel was used as substrate, it was identified that the homogenous growth of coiled CNFs at temperature ranges from 650 oC to 700
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o
C. With increase in temperature there is decrease in diameter of individual fibers. At high
temperature it was also identified that the diameter of growth CNFs were small but in bundle i.e.
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four smaller nanofibers growing out together. The diameter of nanofibers increases with increase in C2H2 concentration in gas flow ratio, whereas helix angle remained approximately same.
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Large quantities of carbon fibers can be directly grown without any use of nano particles on bulk
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Acknowledgments
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metals thereby decreasing the cost of production and making the process simple.
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Authors acknowledge the Panjab University for supporting university lab. Authors would also
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like to thank Inderjit Singh for FESEM image analysis at IISER, Mohali.
References [1]
R.T.K. Baker, P.S. Harris, R.B. Thomas, R.J. Waite, Formation of filamentous carbon from iron, cobalt and chromium catalyzed decomposition of acetylene, J. Catal. 30 (1973) 86–95. doi:10.1016/0021-9517(73)90055-9.
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E.L. Evans, J.M. Thomas, P. a. Thrower, P.L. Walker, Growth of filamentary carbon on metallic surfaces during the pyrolysis of methane and acetone, Carbon N. Y. 11 (1973) 441–445. doi:10.1016/0008-6223(73)90302-3.
[3]
R.T.K. Baker, P.S. Harris, J. Henderson, R.B. Thomas, Formation of carbonaceous deposits from the reaction of methane over nickel, Carbon N. Y. 13 (1975) 17–22.
X. Jian, M. Jiang, Z. Zhou, M. Yang, J. Lu, S. Hu, Y. Wang, D. Hui, Preparation of high
IP
[4]
T
doi:10.1016/0008-6223(75)90252-3.
CR
purity helical carbon nanofibers by the catalytic decomposition of acetylene and their growth mechanism, Carbon N. Y. 48 (2010) 4535–4541.
[5]
US
doi:10.1016/j.carbon.2010.08.035.
Y. Liu, H. Teng, H. Hou, T. You, Nonenzymatic glucose sensor based on renewable
AN
electrospun Ni nanoparticle-loaded carbon nanofiber paste electrode, Biosens. Bioelectron. 24 (2009) 3329–3334. doi:10.1016/j.bios.2009.04.032. J.S. Lee, O.S. Kwon, S.J. Park, E.Y. Park, S.A. You, H. Yoon, L.E.E.E.T. Al, Fabrication
M
[6]
of Ultra fi ne Metal-Oxide- Decorated Carbon Nano fi bers for DMMP Sensor
J. Jang, J. Bae, Carbon nanofiber/polypyrrole nanocable as toxic gas sensor, Sensors
PT
[7]
ED
Application, ACS Nano. 5 (2011) 7992–8001.
Actuators, B Chem. 122 (2007) 7–13. doi:10.1016/j.snb.2006.05.002. L. Ji, X. Zhang, Electrospun carbon nanofibers containing silicon particles as an energy-
CE
[8]
storage medium, Carbon N. Y. 47 (2009) 3219–3226. doi:10.1016/j.carbon.2009.07.039. D.P. Dubal, O. Ayyad, V. Ruiz, P. Gómez-Romero, Hybrid energy storage: the merging of
AC
[9]
battery and supercapacitor chemistries, Chem. Soc. Rev. 44 (2015) 1777–1790. doi:10.1039/C4CS00266K. [10] M.H. Al-Saleh, U. Sundararaj, A review of vapor grown carbon nanofiber/polymer conductive composites, Carbon N. Y. 47 (2009) 2–22. doi:10.1016/j.carbon.2008.09.039. [11] Y. Zhou, F. Pervin, S. Jeelani, P.K. Mallick, Improvement in mechanical properties of carbon fabric-epoxy composite using carbon nanofibers, J. Mater. Process. Technol. 198 (2008) 445–453. doi:10.1016/j.jmatprotec.2007.07.028.
ACCEPTED MANUSCRIPT [12] A. Chambers, C. Park, R.T.K. Baker, N.M. Rodriguez, Hydrogen storage in graphite nanofibers, J. Phys. Chem. B. 102 (1998) 4253–4256. doi:10.1021/jp980114l. [13] A. Chambers, T. Nemes, N.M. Rodriguez, R.T.K. Baker, Catalytic Behavior of Graphite Nanofiber Supported Nickel Particles . 1 . Comparison with Other Support Media, J. Phys. Chem. B. 102 (1998) 5168–5177. doi:10.1021/jp973462g.
T
[14] C.A. Bessel, K. Laubernds, N.M. Rodriguez, R.T.K. Baker, Graphite nanofibers as an
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electrode for fuel cell applications, J. Phys. Chem. B. 105 (2001) 1115–1118.
CR
doi:10.1021/jp003280d.
[15] C. Pham-Huu, N. Keller, G. Ehret, L.J. Charbonniere, R. Ziessel, M.J. Ledoux, Carbon
US
nanofiber supported palladium catalyst for liquid-phase reactions an active and selective catalyst for hydrogenation of cinnamaldehyde into hydrocinnamaldehyde, J. Mol. Catal. A
AN
Chem. 170 (2001) 155–163. doi:10.1016/S1381-1169(01)00055-3. [16] H. Terrones, T. Hayashi, M. Muñoz-Navia, M. Terrones, Y.A. Kim, N. Grobert, R.
M
Kamalakaran, J. Dorantes-Dávila, R. Escudero, M.S. Dresselhaus, M. Endo, Graphitic cones in palladium catalysed carbon nanofibres, Chem. Phys. Lett. 343 (2001) 241–250.
ED
doi:10.1016/S0009-2614(01)00718-7.
PT
[17] C.W. Huang, Y.Y. Li, In situ synthesis of platelet graphite nanofibers from thermal decomposition of poly(ethylene glycol), J. Phys. Chem. B. 110 (2006) 23242–23246.
CE
doi:10.1021/jp064736f.
[18] M. Weisenberger, I. Martin-Gullon, J. Vera-Agullo, H. Varela-Rizo, C. Merino, R.
AC
Andrews, D. Qian, T. Rantell, The effect of graphitization temperature on the structure of helical-ribbon carbon nanofibers, Carbon N. Y. 47 (2009) 2211–2218. doi:10.1016/j.carbon.2009.03.070. [19] M. Endo, Y.A. Kim, T. Hayashi, Y. Fukai, K. Oshida, M. Terrones, T. Yanagisawa, S. Higaki, M.S. Dresselhaus, Structural characterization of cup-stacked-type nanofibers with an entirely hollow core, Appl. Phys. Lett. 80 (2002) 1267–1269. doi:10.1063/1.1450264. [20] W. Huang, X. Zhang, J. Tu, F. Kong, Y. Ning, J. Xu, G. Van Tendeloo, Synthesis and characterization of graphite nanofibers deposited on nickel foams, Phys. Chem. Chem.
ACCEPTED MANUSCRIPT Phys. 4 (2002) 5325–5329. doi:10.1039/b206072h. [21] Y. Suda, K. Maruyama, T. Iida, H. Takikawa, H. Ue, K. Shimizu, Y. Umeda, High-Yield Synthesis of Helical Carbon Nanofibers Using Iron Oxide Fine Powder as a Catalyst, Crystals. 5 (2015) 47–60. doi:10.3390/cryst5010047. [22] C. Singh, T. Quested, C.B. Boothroyd, I. a Kinloch, A.I. Abou-kandil, A.H. Windle, P.
T
Thomas, Synthesis and Characterization of Carbon Nanofibers Produced by the Floating
IP
Catalyst Method Synthesis and Characterization of Carbon Nanofibers Produced by the
CR
Floating Catalyst Method, Society. (2002) 10915–10922. doi:10.1021/jp026159a. [23] S. Motojima, M. Kawaguchi, K. Nozaki, H. Iwanaga, Growth of regularly coiled carbon
US
filaments by Ni catalyzed pyrolysis of acetylene, and their morphology and extension characteristics, Appl. Phys. Lett. 56 (1990) 321–323. doi:10.1063/1.102816.
AN
[24] Y.Y. Fan, H.M. Cheng, Y.L. Wei, G. Su, Z.H. Shen, Influence of preparation parameters on the mass production of vapor-grown carbon nanofibers, Carbon N. Y. 38 (2000) 789–
M
795. doi:10.1016/S0008-6223(99)00178-5.
ED
[25] R.S. Wagner, W.C. Ellis, Vapor-liquid-solid mechanism of single crystal growth, Appl. Phys. Lett. 4 (1964) 89–90. doi:10.1063/1.1753975.
PT
[26] N.B.J. Amelinckx, S., Zhang B. X., Bernaetrs D., Zhang F. X., Ivanov V., A formation
635–639.
CE
mechanism for catalytically grown helix-shaped graphite nanotubes, Science. 265 (1994)
[27] W. Qian, T. Liu, Z. Wang, H. Yu, Z. Li, F. Wei, G. Luo, Effect of adding nickel to iron –
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alumina catalysts on the morphology of as-grown carbon nanotubes, Carbon N. Y. 41 (2003) 2487–2493. [28] I. Martin-Gullon, J. Vera, J.A. Conesa, J.L. González, C. Merino, Differences between carbon nanofibers produced using Fe and Ni catalysts in a floating catalyst reactor, Carbon N. Y. 44 (2006) 1572–1580. doi:10.1016/j.carbon.2005.12.027.
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Detailed experiment and analysis of growth on Inconel
SS 316 Inconel
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Nickel
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CVD with different metals as substrate
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Carbon nanofibers
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ACCEPTED MANUSCRIPT Highlights of present work
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Growth of carbon nanofibers directly on metal substrate using indigenously developed chemical vapour deposition setup. Effect of different transition metal and alloys investigated. Growth of coiled carbon nanofibers on Inconel. Effect of variation in temperature and ratio of carrier gas to precursor gas on morphology studied and reported.
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