by Arunava Jha - DSpace at Jadavpur University

INVESTIGATION ON SOME
NOVEL CARBON AND METAL
OXIDE ONE DIMENSIONAL
NANOSTRUCTURE MATERIALS
Thesis Submitted for the Degree of Doctor of
Philosophy (ENGINEERING)
by
Arunava Jha
Thin Film & Nanoscience Laboratory
School of Materials Science and Nanotechnology
Jadavpur University
Kolkata – 700032, India
------------------------------------------------------------------------------------------ Abstract
Abstract
Recently 1D nanostructures such as wires, rods, belts and tubes have become
the focus of intensive research owing to their unique application in mesoscopic
physics and fabrication of nanoscale devices. It is generally accepted that 1D
nanostructures provide a good system to investigate the dependence of electrical,
optical, thermal transport and mechanical properties on dimensionality and size
reduction (or quantum confinement). They are also expected to play an important role
both as interconnects and functional units in fabricating electronic, optoelectronic,
electrochemical and electromechanical devices with nanoscale dimensions.
Both carbon and metal oxide 1D nanostructures are gaining extreme interest
among the researchers around the world due to their potential utility in various fields
of applications. Carbon 1D nanostructures such as carbon nanotubes (CNTs) have
enormous applications in the field of energy storage, electrochemical supercapacitor,
field emission devices, transistors, sensors etc. On the other hand 1D metal oxide
such as ZnO is also proving itself to be a good candidate for many applications like
nanoscale electronic devices, field emitter etc.. 1D Metal oxide like Mn3O4 nanorods
has greater applications as optical and magneto-electric devices. Both CNTs and
Mn3O4 show good sensing and thermal conductivity. So a comparative study of both
the materials will help us to understand their individual properties and whether it is
possible to reinforce one’s advantage to another.
Synthesis of undoped and Zn doped hausmannite Mn3O4 nanorods was
achieved through a simple hydrothermal route. Scanning electron microscopic studies
showed that due to in-situ Zn doping a structural deformation from Mn3O4 nanorods to
a mixture of Mn3O4 nanorods and nanoparticles occurred. The amount of
nanoparticles in the mixture increased with the increase of doping percentage. X-ray
diffraction studies, transmission electron microscopy and selected area electron
diffraction pattern revealed that both the nanorods and the nanoparticles were
hausmannite Mn3O4. X-ray photoelectron spectroscopic studies confirmed successful
zinc doping in Mn3O4. Microscopic studies revealed that the average diameters of
Mn3O4 nanorods and nanoparticles were of 200 nm and 70 nm respectively. The
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------------------------------------------------------------------------------------------ Abstract
possible growth mechanism and the reasons behind the formation of nanoparticles
along with nanorods are discussed briefly. UV-vis spectroscopic studies showed a
continuous increase in the energy bandgap of Mn3O4 with the increase in Zn doping
percentage.
Different one dimensional (1D) carbon nanostructures, such as carbon
nanonoodles (CNNs), carbon nanospikes (CNSs) and carbon nanotubes (CNTs) have
been synthesized via thermal chemical vapour deposition (HT-CVD) technique. The
different 1D morphologies were synthesized by varying the substrate material and the
deposition conditions. The as-prepared samples were characterized by X-ray
diffraction
(XRD),
ﬁeld
emission
scanning
electron
microscope
(FESEM)
and
transmission electron microscope (TEM). FESEM and TEM images showed that the
diameters of the CNNs and CNTs were ∼40 nm while the diameters of the CNSs were
around 100 nm. Field emission studies of the as-prepared samples showed that CNSs
to be a better ﬁeld emitter than CNNs, whereas CNTs are the best among the three
producing large emission current. The variation of ﬁeld emission properties with interelectrode distance has been studied in detail. Also the time dependent ﬁeld emission
studies of all the nanostructures have been carried out.
Along with crystalline 1D carbon nanostructures, amorphous carbon nanotubes
(a-CNTs) were also synthesized by a simple process using ammonium chloride and
ferrocene at a low temperature (~250 0C) in open atmosphere. Previous reports have
established that proper functionalization can improve the field emission property of
CNTs. So the as-prepared samples were oxidized by a simple acid treatment and
further functionalized with stearic acid. For the confirmation of oxidation and
functionalization, the pristine and the modified a-CNTs were characterized by Fourier
transformed infrared spectroscopy, transmission and scanning electron microscopy.
The as-prepared samples showed good field emission (FE) and the FE characteristics
were significantly improved for the stearic acid functionalized samples compared to
the pristine sample. The effects of inter-electrode distance on the FE properties of the
functionalized samples were also studied.
Amorphous carbon nanotubes (ACNTs) were synthesized by following a simple
chemical route with ammonium chloride and ferrocene taken as starting materials and
heating at 250 oC under open atmosphere. The as-prepared samples were oxidized and
13
------------------------------------------------------------------------------------------ Abstract
chemically activated by simple acid treatment and further functionalized by copper
phthalocyanine (CuPc). The attachment of CuPc at the walls of the nanotubes was
investigated by Fourier transformed infrared spectroscopy, X-ray photoelectron
spectroscopy, transmission and scanning electron microscopy. The field emission
property of ACNTs was found to be greatly enhanced after coating them with CuPc.
The effects of inter-electrode distance on the field emission properties of the
functionalized samples were also studied.
Crystalline coiled carbon nano/micro fibers in thin film form have been
synthesized via direct current plasma enhanced chemical vapor deposition (PECVD) on
copper substrates with acetylene as a carbon precursor at 10 mbar pressure and 750
oC
substrate temperature. The as-prepared samples were characterized by x-ray
diffraction (XRD) analysis, scanning electron microscopy (SEM) and high resolution
transmission electron microscopy (HRTEM). The variation of field emission properties
with inter-electrode distance has been studied in detail. The field emission properties
of the coiled carbon fibrous thin films are compared with that of crystalline
multiwalled carbon nanotubes and other carbon nanostructures.
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Contents
Contents:
Preface
Contents
List of Publications
Abstract
4
6
9
12
Chapter I
Introduction, Aims and Objectives
15 – 63
What is Nanotechnology ……………………………………
Why 1 Dimensional ………………………………………….
About Carbon …………………………………………………
About Mn3O4…………………………………………………..
Aims and Objectives …………………………………………
References ……………………………………………………..
16
29
33
50
52
57
A brief review of Past work
64 – 95
1.1
1.2
1.3
1.4
1.5
1.6
Chapter II
2.1
2.2
2.3
2.4
2.5
2.6
Chapter III
Growth of 1D Carbon nanostructure via thermal CVD 65
Models of Catalytic growth ………………………………… 69
Amorphous CNT and Functionalization………………… 75
Mn3O4Nanorod ………………………………………………. 79
Field electron Emission …………………………………….. 81
References …………………………………………………….. 85
Instruments and Apparatus
3.1
3.2
3.3
96 – 115
General Description of Major Synthesis Apparatus
3.1.1 High temp. Thermal CVD …………………………. 97
3.1.2 Furnace and Oven …………………………………. 99
3.1.3 Autoclave …………………………………………….. 100
Major Supporting Accessories
3.2.1 Electric Multi-meter ………………………………… 101
3.2.2 Magnetic stirrer, Ultrasonicator and Centrifuge 102
3.2.3 RF Magnetron Sputterring ………………………… 103
General Description of Major Characterizing
Apparatus
3.3.1 Field Emission measurement ……………………. 105
3.3.2 X-Ray Diffractometer ………………………………. 106
3.3.3 FTIR Spectrometer ………………………………….. 107
3.3.4 UV-vis-NIR Spectrophotometer …………………… 109
3.3.5 X-Ray photoelectron Spectrometer ……………… 111
3.3.6 Scanning electron Microscope ……………………. 112
3.3.7 High resolution Transmission Electron
microscope …………………………………………… 114
6
--------------------------------------------------------------------------------------Chapter IV
“A comparative study of field emission from
different one Dimensional carbon
nanostructures synthesized via thermal CVD
system”
4.1
4.2
4.3
4.4
4.5
Chapter V
Contents
116 –130
Abstract ………………………………………………………... 117
Introduction …………………………………………………… 117
Experimental
4.2.1 Carbon nanospikes ………………………………… 118
4.2.2 Carbon nanonoodles ………………………………. 119
4.2.3 Carbon nanotubes …………………………………. 119
4.2.4 Characterization and FE ………………………….. 119
Results and Discussion
4.3.1 XRD analysis ……………………………………….. 120
4.3.2 FESEM studies ……………………………………… 121
4.3.3 TEM studies …………………………………………. 122
4.4.2 Field emission studies …………………………….. 124
Conclusion ……………………………………………………. 128
References …………………………………………………….. 129
“Improved field emission from amorphous
carbon nanotubes by surface functionalization
131 – 146
with stearic acid”
5.1
5.2
5.3
5.4
5.5
Chapter VI
Abstract ………………………………………………………... 132
Introduction …………………………………………………… 132
Experimental
5.2.1 Characterization and FE ………………………….. 134
Results and Discussion
5.3.1 FTIR analysis ……………………………………….. 134
5.3.2 Dispersion analysis ……………………………….. 136
5.3.3 Morphological analysis By FESEM and HRTEM 137
5.3.4 FE analysis ………………………………………….. 139
5.3.5 Possible explanation of The enhancement …….. 142
Conclusion ……………………………………………………. 144
References …………………………………………………….. 145
“Surface modification of amorphous carbon
nanotubes with copper phthalocyanine leading
to enhanced field emission”
147 – 164
6.1
6.2
6.3
Abstract ………………………………………………………... 148
Introduction …………………………………………………… 148
Experimental
6.2.1 Synthesis and functionalization of ACNTs ……. 149
6.2.2 Characterization and FE measurement ……….. 150
Results and Discussion
6.3.1 FTIR analysis ……………………………………….. 151
6.3.2 Dispersion analysis ……………………………….. 152
7
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6.4
6.5
Chapter VII
Contents
6.3.3 XPS analysis ………………………………………… 154
6.3.4 Morphological analysis By FESEM and TEM …. 155
6.3.5 Thermal study ………………………………………. 157
6.3.6 FE analysis ………………………………………….. 158
Conclusion ……………………………………………………. 162
References …………………………………………………….. 163
“Structural transformation from
Mn3O4nanorods to nanoparticles and bandgap
tuning via Zn doping”
165 – 183
7.1
7.2
7.3
7.4
7.5
Chapter VIII
Abstract ………………………………………………………... 166
Introduction …………………………………………………… 166
Experimental
7.2.1 Synthesis process ………………………………….. 167
7.2.2 Charaterization ……………………………………... 168
Results and Discussion
7.3.1 Phase and Composition study …………………… 168
7.3.2 FTIR analysis ……………………………………….. 169
7.3.3 XPS analysis ………………………………………… 171
7.3.4 Morphology analysis ………………………………. 173
7.3.5 Growth Mechanism of Mn3O4 …………………….. 176
7.3.6 Energy bandgap variation ……………………….. 179
Conclusion ……………………………………………………. 180
References …………………………………………………….. 181
Generalized Conclusion and Future Scopes of
Work
8.1
8.2
184 – 188
Generalized Conclusion ….………………………………… 185
Future scopes of work ……………………………………… 188
8

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