Formation Of Iron Oxide Nanowires By Using Thermal Oxidation Of Iron.
FORMATION OF IRON OXIDE NANOWIRES BY USING
THERMAL OXIDATION OF IRON
NUR SYAFINI BINTI SA’AD
B051110092
UNIVERSITI TEKNIKAL MALAYSIA MELAKA
2015
B051110092
BACHELOR OF MANUFACTURING ENGINEERING (ENGINEERING MATERIALS) (HONS.)
2015 UTeM
UNIVERSITI TEKNIKAL MALAYSIA MELAKA
FORMATION OF IRON OXIDE NANOWIRES BY USING
THERMAL OXIDATION OF IRON
This report submitted in accordance with requirement of the Universiti Teknikal
Malaysia Melaka (UTeM) for the Bachelor Degree of Manufacturing Engineering
(Engineering Materials)(Hons.)
by
NUR SYAFINI BINTI SA’AD
B051110092
920522-11-5350
FACULTY OF MANUFACTURING ENGINEERING
2015
UNIVERSITI TEKNIKAL MALAYSIA MELAKA
BORANG PENGESAHAN STATUS LAPORAN PROJEK SARJANA MUDA
TAJUK: Formation of Iron Oxide Nanowires by Using Thermal Oxidation of Iron
SESI PENGAJIAN: 2014/15 Semester2
Saya NUR SYAFINI BINTI SA’AD
mengaku membenarkan Laporan PSM ini disimpan di Perpustakaan Universiti
Teknikal Malaysia Melaka (UTeM) dengan syarat-syarat kegunaan seperti berikut:
1. Laporan PSM adalah hak milik Universiti Teknikal Malaysia Melaka dan penulis.
2. Perpustakaan Universiti Teknikal Malaysia Melaka dibenarkan membuat salinan
untuk tujuan pengajian sahaja dengan izin penulis.
3. Perpustakaan dibenarkan membuat salinan laporan PSM ini sebagai bahan
pertukaran antara institusi pengajian tinggi.
4. **Silatandakan ( )
SULIT
(Mengandungi maklumat yang berdarjah keselamatan
atau kepentingan Malaysia sebagaimana yang termaktub
dalam AKTA RAHSIA RASMI 1972)
TERHAD
(Mengandungi maklumat TERHAD yang telah ditentukan
oleh organisasi/badan di mana penyelidikan dijalankan)
TIDAK TERHAD
Disahkanoleh:
AlamatTetap:
Cop Rasmi:
Lorong Mesin Padi
Kampung Alor Limbat
21400 Marang, Terengganu
Tarikh: 30 Jun 2015
Tarikh: 30 Jun 2015
**Jika Laporan PSM ini SULIT atau TERHAD,sila lampirkan surat daripada pihak berkuasa/organisasi
berkenaan dengan menyatakan sekali sebab dan tempoh laporan PSM ini perlu dikelaskan sebagai
SULIT atau TERHAD.
DECLARATION
I hereby, declared this report entitled “Formation of Iron Oxide Nanowires by
Using Thermal Oxidation of Iron” is the results of my own research except as cited
in references.
Signature
:
………………………………
Author’s Name
:
NUR SYAFINI BINTI SA’AD
Date
:
30 Jun 2015
APPROVAL
This report is submitted to the Faculty of Manufacturing Engineering of UTeM
as a partial fulfillment of the requirements for the degree of Bachelor of
Manufacturing Engineering (Engineering Materials) (Hons.). The member of the
supervisory is as follow:
………………………………
(Project Supervisor)
ABSTRAK
Oksida ferum nanowires digunakan secara meluas dalam pelbagai aplikasi,
termasuklah fotopemangkinan. Konvensional, oksida ferum nanowires dihasilkan
oleh teknik-teknik seperti; proses sol-gel, kaedah templat, penguraian terma, proses
hidroterma
Walau bagaimanapun, teknik-teknik ini mahal dan rumit. Oleh itu,
projek ini bertujuan untuk menghasilkan oksida ferum nanowires dengan
menggunakan pengoksidaan terma ferum. Beberapa paremeter telah disiasat seperti
kesan masa pengoksidaan, suhu pengoksidaan dan keadaan pada substrat. Morfologi
dan fasa Fe2O3 nanowires yang dibentuk telah disifatkan. Pemerhatian FESEM telah
menunjukkan bahawa Fe2O3 struktur nanowires telah terbentuk pada kepingan Fe
tulen. XRD dan spektroskopi Raman mengesahkan fasa fasa: α- Fe2O3, FeO dan
Fe3O4 terbentuk selepas process pengoksidaan manakala EDX digunakan untuk
memastikan nanowires yang terhasil mempunyai oksigen dan ferum. Raman
spektroskopi telah digunakan untuk menyokong morfologi dan fasa yang diperoleh
dari analisis SEM dan XRD. Sampel (pengoksidaan pada 180 min, 500 C, dalam
udara tanpa menitikkan asid sulfurik) adalah tertakluk kepada ujian degradasifoto di
bawah cahaya UV. Hasil daripada degradasifoto ini menunjukkan semakin lama
masa larutan methyl orange terdedah kepada cahaya UV, semakin pudar larutan itu.
Untuk memastikan larutan itu mempunyai perubahan warna, analisis menggunakan
UV visible digunakan. Berdasarkan keputusan yang diperoleh, maka boleh
disimpulkan bahawa larutan itu berlaku proses degradasi apabila masa pendedahan
kepada cahaya semakin menigkat.
i
ABSTRACT
An iron oxide nanowire is used widely in a range of applications, which
include photocatalysis. Conventionally, iron oxide nanowires are produced by
techniques such as; sol-gel process, template method, thermal decomposition,
hydrothermal process However, these techniques are costly and complicated.
Hence, this project serves to fabricate the iron oxide nanowires by using thermal
oxidation of iron. Several parameters were investigated such as the effect of
oxidation time, oxidation temperature and condition on the substrate. The
morphologies and phases of Fe2O3 nanowires formed were characterized. FESEM
observation showed that Fe2O3 nanowires structure was successfully formed on pure
Fe foil. XRD and Raman spectroscopy confirmed variant phase: α- Fe2O3, FeO and
Fe3O4 occurred after oxidizing while EDX was used to confirm that the nanowires
consisted of oxygen and iron. Raman spectroscopy was used to support the
morphologies and phases observed by SEM and XRD. The samples (oxidized at 180
min, 500C, in air without dropping sulphuric acid) were subjected to
photodegradation testing under UV light conditions. The result obtain from this
photodegradation shows that, as increase the time of methyl orange solution exposed
to UV light, the solution is become fades. To ensure that the solution has changed
color, UV visible analysis is used. Based on the results obtained, it can be concluded
that the solution was effective degradation process when the time of exposure to light
progressively increase.
ii
DEDICATION
Dedicated to my beloved family members especially my parents, lecturers,
and also to all my friends.
iii
ACKNOWLEDGEMENT
I would like to take this opportunity to express my gratefulness and gratitude
to those who have rendered their valuable advice, support and guidance to me during
the long journey of completing this research. First and foremost, I would like to
thank my supervisor Dr. Syahriza Ismail for her relentless support, advice and
guidance throughout the entire project. Not to forget the research members: Azreen
and Nadia for all the assistance and guidance provided all this while. I am greatly
touched by the commitments and dedications they have shown. Without the support
and guidance, I would not be able to complete this research. Besides, without the
moral support and understanding from my family especially my father, En Saad Talib
and my late mother, Pn Kelsom Musa, it would be impossible for me to complete this
research. I wish to express my biggest gratefulness and love to my family members.
Finally, I wish to say that I treasure very much the friendship of my friends who have
been very supportive in providing all necessary help and advice during the journey of
completing this research.
iv
TABLE OF CONTENT
Abstrak
i
Abstract
ii
Dedication
iii
Acknowledgement
iv
Table of Content
v
List of Tables
viii
List of Figures
ix
CHAPTER 1: INTRODUCTION
1.1
Background
1
1.2
Problem Statement
5
1.3
Research Objective
6
1.4
Scopes of Work
6
1.5
Project Outline
6
CHAPTER 2: LITERATURE REVIEW
2.1
Introduction to Nanostructure
8
2.2
Metal Valve Oxide-iron Oxide: Polymorphs and Properties
10
2.3
Technique to Produce Nanowires
14
2.3.1 Hydrothermal process
14
2.3.2 Sol-gel process
15
2.3.3 Template-assisted electrodeposition
15
2.3.4 Thermal decomposition
16
2.3.5 Thermal oxidation
17
Application of Iron Oxide Nanowires
21
2.4.1 Catalyst
21
2.4
v
2.4.2 Photoelectrochemical cells
22
2.4.3 Photocatalyst
24
CHAPTER 3: METHODOLOGY
3.1
Introduction
27
3.2
Materials
29
3.3
Design of Experiment
29
3.3.1 Substrate preparation and cleaning
29
3.3.2 Thermal oxidation process
30
3.3.3 Thermal oxidation parameter
31
Characterization
31
3.4.1 Morphology characterization
32
3.4
3.4.1.1 Scanning electron microscopy
32
3.4.2 Structural characterization
32
3.4.2.1 X-ray diffraction
32
3.4.2.2 Electron dispersive X-ray
33
3.4.2.3 Raman spectroscopy
34
3.4.3 Photodegradation testing
3.4.3.1 UV lamp chamber
34
34
CHAPTER 4: RESULTS AND DISCUSSIONS
4.1
4.2
4.3
Fe2O3 Nanowires Formation by Thermal Oxidation Process
36
4.1.1 Effect of growth time
37
4.1.2 Effect of sulphuric acid on the morphology of samples
39
Mechanism of Fe2O3 Nanowires Formation
41
4.2.1 Mechanism of Fe2O3 nanostructure in air
41
4.2.2 Mechanism of Fe2O3 nanostructure in air by dropping H2SO4
43
43
X-Ray Diffraction (XRD)
vi
4.4
4.4
4.3.1 Different time effect
44
4.3.2 Influence of H2SO4 on the samples
45
Raman Spectroscopy Analysis
47
4.4.1 Effect of growth time
47
4.4.2 Effect of sulphuric acid (H2SO4)
49
4.4.3 Effect of temperature
49
Photodegradation Testing
51
4.5.1 Mechanism of photodegradation
53
CHAPTER 5: CONCLUSIONS AND RECOMMENDATIONS
5.1
Conclusions
55
5.2
Recommendations
56
REFERENCES
57
vii
LIST OF TABLES
2.1
Physical and Magnetic Properties of Iron Oxide
11
3.1
The List of Materials Used in the Research
29
3.2
List of Changing Parameter
31
4.1
Raman shift of variant phases iron oxide that match Raman shift
of iron oxide nanowires at 300 C, for 60 min
48
4.2
Raman shift of variant phases iron oxide that match Raman shift of
iron oxide nanowires at 300 C, for 180 min
48
4.3
Raman shift of variant phases iron oxide that match Raman shift of
iron oxide nanowires at 300 C, for 300 min
48
4.4
Raman shift of variant phases iron oxide that match Raman shift of
iron oxide nanowires at 180 min, for 300 C
50
4.5
Raman shift of variant phases iron oxide that match Raman shift of
iron oxide nanowires at 180 min, for 500 C
51
Raman shift of variant phases iron oxide that match Raman shift of
iron oxide nanowires at 180 min, for 700 C
51
Sample used for photodegradation of methyl orange
51
4.6
4.7
viii
LIST OF FIGURES
1.1
Morphology of single nanowires
2
1.2
Schematic diagram of single nanowires array
2
1.3
Various synthesized method of nanowires
3
1.4
Application of hematite nanowires
4
1.5
Photocatalytic process
4
2.1
Type of Nanomaterials structure (A) 0D spheres and clusters,
8
(B) 1D nanofibers, wires, and rods, (C) 2Dfilms, plates, and
networks, (D) 3D nanomaterials
2.2
Typical SEM image of different types of 1D nanostructure, (A)
10
nanowires, (B) nanorods, (C) nanotubes, (D) nanobelts, (E)
nanoribbons, and (F) hierarchical nanostructure
2.3
Crystal structure of magnetite (Fe3O4)
12
2.4
Crystal structure of hematite (α–Fe2O3)
13
2.5
Crystal structure of maghemite (γ- Fe2O3)
13
2.6
Schematic diagram of hydrothermal process
14
2.7
Schematic diagram of sol-gel process
15
ix
2.8
Schematic
diagram
of
template-assisted
electrodeposition
16
method
2.9
Schematic diagram of thermal decomposition method
17
2.10
Schematic diagram of thermal oxidation process
18
2.11
Step of iron oxide nanowire growth mechanism: 1)oxygen
19
adsorption, 2)surface oxidization to form nuclei, 3)nuclei
arrangement and 4)formation of nanowires
2.12
The image of Fe substrates oxidize at two different temperatures,
20
2.13
The general catalytic cycle.
22
2.14
The change in activation energy brought about by a catalyst.
22
2.15
Mechanism of phoelectrochemical (PEC) cells
23
2.16
Mechanism of photocatalyst reaction
25
3.1
Flow chart of the experimental work.
28
3.2
Vacuum furnace setup tor thermal oxidation process
30
3.3
Field emission SEM machine
32
3.4
X-Ray diffraction (XRD) machine
33
4)formation of nanowires
(a) 400 C and (b) 600 C and the different type of layer form
The schematic diagram of the thermal oxidation process.
3.5
Equipment set-up for photodegradation of methyl orange
x
35
4.1
FESEM images of Fe2O3 nanowires formed by thermal
37
oxidation process within time (a) 60 min, (b)180 min and (c) 300
min at 300 C in air
4.2
EDX spectra of Fe2O3 nanowires formed
39
4.3
FESEM images of samples synthesized by reaction of H2SO4
40
with Fe at time (a) 60 min, (b) 180 min and (c) 300 min at 300
C in air
4.4
Schematic stress-driven mechanism of Fe2O3 nanowires growth
42
via diffusion
4.5
XRD patterns for Fe substrate formed by thermal oxidation
44
process with time (a) 60 min, (b) 180 min and (c) 300 min at 300
C in air
4.6
XRD patterns for Fe substrate formed by thermal oxidation
45
process with pattern focused region of graph 2Ɵ=20-50
4.7
XRD patterns for Fe substrate formed by thermal oxidation
46
4.8
XRD patterns for Fe substrate formed by thermal oxidation
46
process with time at 300 C in air by dropping H2SO4
process with pattern focused region of graph 2Ɵ=20-50.
4.9
Raman spectrum for iron oxide nanowires formed by thermal
47
4.10
Raman spectrum for iron oxide nanowires formed by thermal
49
oxidation process with time at 300 C in air.
oxidation process with time at 300 C in air. by dropping H2SO4
xi
4.11
Raman spectrum for iron oxide nanowires formed by thermal
50
oxidation process with temperature at 180 min in air
4.12
Methyl orange solution degrade as time exposed to UV light
52
4.13
UV-visible analysis at different time exposed to UV light.
53
xii
CHAPTER 1
INTRODUCTION
This chapter describe the introduction of the project. In this project, thermal
oxidation process was used to form iron oxide nanowires. This chapter also include
background, problem statement, objective, scope and project outline of the study.
1.1
Background
Nanostructure refers to materials system with at least one dimension is in the
range of ~1-100nm. In a nanostructure, electrons are freely move in other dimension
eventhough there are confined in nanoscale dimension. As compared to individual
atom and molecules, the nanostructure is mostly unique.
Nanowires and nanobelts are semi one dimensional nanostructure based
oxides, they have pulled in much consideration lately. They show unordinary optical,
electronic, attractive and mechanical properties as contrasted with those of mass
materials. It is because of the huge surface related deformity starting from the high
surface to volume degrees. Moreover, some paramount properties of one dimensional
nanostructured based oxide are great high temperature steadiness, oxidation safety
and stable electric properties. Thus, it demonstrates their potential basic building
blocks for new classes of environmentally conscious electronics (Yang et al., 2010).
Since the nanowires is studied, some paramount is important which are the control of
morphology, size and growth direction. Figure 1.1 shows the morphology of
nanowire (Hiralal et al., 2008a) while Figure 1.2 shows the schematic diagram of
single nanowire arrays (Rahim et al., 2014). In addition, the different of
1
morphologies get will affect the properties with unique application. A suitable
alignment of substrate is needed for an ensemble of nanowires (Wen et al., 2005).
Figure 1.1: Morphology of single nanowires (Hiralal et al., 2008).
Figure 1.2: Schematic diagram of single nanowire array (Rahim et al., 2014).
Recently, nanowires have been synthesized by several different methods,
such as the hydrothermal process, the template method, the vapour–solid process,
sol–gel technique and thermal decomposition (Liu et al., 2008). Nevertheless,
thermal oxidation in various oxidizing atmosphere is a most simple, cheap and direct
2
procedure to form iron oxide nanowires (Grigorescu et al., 2012) shows in Figure
1.3.
Figure 1.3: Various synthesized method of nanowires.
The growth of nanowires on the surface of iron is depending on the condition.
Under typical condition, layer oxide will be formed, as hematite, magnetite and
wustite. Hematite is formed at outer layer while magnetite as an intermediate layer
and wustite layer form on iron iron substrate. As n-type semiconductor, which has
bandgap 2.1 eV, hematite is environmental friendly, not poisonous, corrosion
resistant and also the cost is low. Figure 1.4 shows the usage of hematite.
3
Figure 1.4: Application of hematite nanowires
Among of these application, one of interesting is as photocatalyst (Figure
1.5). Photocatalytic reactions promoted by aqueous suspensions of nano sized
transition metal oxides have been subject of abundant number of resent research
(Bakardijeva et al., 2007) with the semiconductor performance, iron oxide is use in
solar photoelectrolysis cells. Hematite is a good catalyst for photooxidation of
sulphite. The details on this iron oxide will be reviewed in chapter 2.
Figure 1.5: Photocatalytic process (Ctibor et al., 2013)
4
1.2
Problem Statement
Since the time that Fujishima and Honda reported in 1972, TiO2
photoelectrode methodology is utilized to create hydrogen from water. Ways and
intends to utilize daylight as an essential vitality hotspot for hydrogen fuel era has
been an exceptionally examined point in science and engineering, with a specific end
goal to accomplish an upgraded daylight reaction, materials must have a suitably low
band crevice and ready to part water, and additionally have suitable band edge
positions in respect to the red-ox capability of water. Subsequently, hematite, with
band hole of 2.1 eV has recovered solid examination enthusiasm to be utilized as
terminal water part for hydrogen generation. These are because of the cost, less
advanced yet plentiful materials.
Moreover, because of the looked into that had being carried out, it
demonstrated that, the examination about arrangement of iron oxide nanowires by
utilizing warm oxidation system was very constrained. It is accepted that nanowires
develop from tip while reactant (metal) diffuse by means of the surface from the
metal substrate. However the accurate instrument of development is a long way from
clear. All the more as of late, different gatherings have returned to the spontaneous
development of oxide nanowires by warm oxidation of metallic substrates (Fe, Zn
and Cu), despite the fact that a definite orderly study is needing.
Photocatalytic response advanced by watery suspensions of nano estimated
move metals oxide have been subject plenteous number of exploration (Bakardijeva
et al., 2007). Iron oxide has been concentrated on broadly for utilization in sunlight
based photoelectrolysis cells. Bamba et.al., (2006) considered the photocatalytic
oxidation of a few dangers at TiO2 and Fe2O3, surfaces. They found that TiO2
powder is dynamic photocatalyst for cyanide oxidation, while no oxidation was
watched for Fe2O3. Recently a few studies exhibited the confirmation for photograph
reactant arrangement of OH radicals. The era of OH radicals is attained through the
usage of costly oxidants such ozone and H2O2 often in mix, with or without UV
radiation. Nonetheless, in this theory, the photocatalytic action of iron oxide got by
warm oxidation technique which is this system is basic and immediate method.
5
1.3
Research Objectives
This research is about the formation of iron oxide nanowires and followings
are the objectives for this work:
a) To produce the iron oxide nanowires formed by thermal oxidation
b) To study the mechanism of iron oxide nanowires by thermal oxidation
c) To study the photocatalysis of iron oxide formed by thermal oxidation
1.4
Scopes of Work
This research covered the study on the formation of Fe2O3 nanowires. For the
synthesis of Fe2O3nanowires, thermal oxidation process was selected. For thermal
oxidation process, the effect of temperature, condition on the substrate and time were
studied. Besides, the photocatalytic application was also considered.
Phase and morphology characterization on the Fe2O3 nanowires was examined by
using Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), Electron
Dispersive X-Ray Spectroscopy (EDX), Raman Spectroscopy, UV Visible
Spectrometry and UV lamp chamber.
1.5
Project Outline
This project was conducted to form the iron oxide nanowires structure by
thermal oxidation process. This process was performed in vacuum furnace at
temperature 300 C – 700 C to form the nanowires. The photocatalytic ability of the
formed oxides it tested by using the UV light irradiation.
Chapter one is the introduction for this whole project while in the chapter two
is explain about nanostructure materials, thermal oxidation process and also the
6
THERMAL OXIDATION OF IRON
NUR SYAFINI BINTI SA’AD
B051110092
UNIVERSITI TEKNIKAL MALAYSIA MELAKA
2015
B051110092
BACHELOR OF MANUFACTURING ENGINEERING (ENGINEERING MATERIALS) (HONS.)
2015 UTeM
UNIVERSITI TEKNIKAL MALAYSIA MELAKA
FORMATION OF IRON OXIDE NANOWIRES BY USING
THERMAL OXIDATION OF IRON
This report submitted in accordance with requirement of the Universiti Teknikal
Malaysia Melaka (UTeM) for the Bachelor Degree of Manufacturing Engineering
(Engineering Materials)(Hons.)
by
NUR SYAFINI BINTI SA’AD
B051110092
920522-11-5350
FACULTY OF MANUFACTURING ENGINEERING
2015
UNIVERSITI TEKNIKAL MALAYSIA MELAKA
BORANG PENGESAHAN STATUS LAPORAN PROJEK SARJANA MUDA
TAJUK: Formation of Iron Oxide Nanowires by Using Thermal Oxidation of Iron
SESI PENGAJIAN: 2014/15 Semester2
Saya NUR SYAFINI BINTI SA’AD
mengaku membenarkan Laporan PSM ini disimpan di Perpustakaan Universiti
Teknikal Malaysia Melaka (UTeM) dengan syarat-syarat kegunaan seperti berikut:
1. Laporan PSM adalah hak milik Universiti Teknikal Malaysia Melaka dan penulis.
2. Perpustakaan Universiti Teknikal Malaysia Melaka dibenarkan membuat salinan
untuk tujuan pengajian sahaja dengan izin penulis.
3. Perpustakaan dibenarkan membuat salinan laporan PSM ini sebagai bahan
pertukaran antara institusi pengajian tinggi.
4. **Silatandakan ( )
SULIT
(Mengandungi maklumat yang berdarjah keselamatan
atau kepentingan Malaysia sebagaimana yang termaktub
dalam AKTA RAHSIA RASMI 1972)
TERHAD
(Mengandungi maklumat TERHAD yang telah ditentukan
oleh organisasi/badan di mana penyelidikan dijalankan)
TIDAK TERHAD
Disahkanoleh:
AlamatTetap:
Cop Rasmi:
Lorong Mesin Padi
Kampung Alor Limbat
21400 Marang, Terengganu
Tarikh: 30 Jun 2015
Tarikh: 30 Jun 2015
**Jika Laporan PSM ini SULIT atau TERHAD,sila lampirkan surat daripada pihak berkuasa/organisasi
berkenaan dengan menyatakan sekali sebab dan tempoh laporan PSM ini perlu dikelaskan sebagai
SULIT atau TERHAD.
DECLARATION
I hereby, declared this report entitled “Formation of Iron Oxide Nanowires by
Using Thermal Oxidation of Iron” is the results of my own research except as cited
in references.
Signature
:
………………………………
Author’s Name
:
NUR SYAFINI BINTI SA’AD
Date
:
30 Jun 2015
APPROVAL
This report is submitted to the Faculty of Manufacturing Engineering of UTeM
as a partial fulfillment of the requirements for the degree of Bachelor of
Manufacturing Engineering (Engineering Materials) (Hons.). The member of the
supervisory is as follow:
………………………………
(Project Supervisor)
ABSTRAK
Oksida ferum nanowires digunakan secara meluas dalam pelbagai aplikasi,
termasuklah fotopemangkinan. Konvensional, oksida ferum nanowires dihasilkan
oleh teknik-teknik seperti; proses sol-gel, kaedah templat, penguraian terma, proses
hidroterma
Walau bagaimanapun, teknik-teknik ini mahal dan rumit. Oleh itu,
projek ini bertujuan untuk menghasilkan oksida ferum nanowires dengan
menggunakan pengoksidaan terma ferum. Beberapa paremeter telah disiasat seperti
kesan masa pengoksidaan, suhu pengoksidaan dan keadaan pada substrat. Morfologi
dan fasa Fe2O3 nanowires yang dibentuk telah disifatkan. Pemerhatian FESEM telah
menunjukkan bahawa Fe2O3 struktur nanowires telah terbentuk pada kepingan Fe
tulen. XRD dan spektroskopi Raman mengesahkan fasa fasa: α- Fe2O3, FeO dan
Fe3O4 terbentuk selepas process pengoksidaan manakala EDX digunakan untuk
memastikan nanowires yang terhasil mempunyai oksigen dan ferum. Raman
spektroskopi telah digunakan untuk menyokong morfologi dan fasa yang diperoleh
dari analisis SEM dan XRD. Sampel (pengoksidaan pada 180 min, 500 C, dalam
udara tanpa menitikkan asid sulfurik) adalah tertakluk kepada ujian degradasifoto di
bawah cahaya UV. Hasil daripada degradasifoto ini menunjukkan semakin lama
masa larutan methyl orange terdedah kepada cahaya UV, semakin pudar larutan itu.
Untuk memastikan larutan itu mempunyai perubahan warna, analisis menggunakan
UV visible digunakan. Berdasarkan keputusan yang diperoleh, maka boleh
disimpulkan bahawa larutan itu berlaku proses degradasi apabila masa pendedahan
kepada cahaya semakin menigkat.
i
ABSTRACT
An iron oxide nanowire is used widely in a range of applications, which
include photocatalysis. Conventionally, iron oxide nanowires are produced by
techniques such as; sol-gel process, template method, thermal decomposition,
hydrothermal process However, these techniques are costly and complicated.
Hence, this project serves to fabricate the iron oxide nanowires by using thermal
oxidation of iron. Several parameters were investigated such as the effect of
oxidation time, oxidation temperature and condition on the substrate. The
morphologies and phases of Fe2O3 nanowires formed were characterized. FESEM
observation showed that Fe2O3 nanowires structure was successfully formed on pure
Fe foil. XRD and Raman spectroscopy confirmed variant phase: α- Fe2O3, FeO and
Fe3O4 occurred after oxidizing while EDX was used to confirm that the nanowires
consisted of oxygen and iron. Raman spectroscopy was used to support the
morphologies and phases observed by SEM and XRD. The samples (oxidized at 180
min, 500C, in air without dropping sulphuric acid) were subjected to
photodegradation testing under UV light conditions. The result obtain from this
photodegradation shows that, as increase the time of methyl orange solution exposed
to UV light, the solution is become fades. To ensure that the solution has changed
color, UV visible analysis is used. Based on the results obtained, it can be concluded
that the solution was effective degradation process when the time of exposure to light
progressively increase.
ii
DEDICATION
Dedicated to my beloved family members especially my parents, lecturers,
and also to all my friends.
iii
ACKNOWLEDGEMENT
I would like to take this opportunity to express my gratefulness and gratitude
to those who have rendered their valuable advice, support and guidance to me during
the long journey of completing this research. First and foremost, I would like to
thank my supervisor Dr. Syahriza Ismail for her relentless support, advice and
guidance throughout the entire project. Not to forget the research members: Azreen
and Nadia for all the assistance and guidance provided all this while. I am greatly
touched by the commitments and dedications they have shown. Without the support
and guidance, I would not be able to complete this research. Besides, without the
moral support and understanding from my family especially my father, En Saad Talib
and my late mother, Pn Kelsom Musa, it would be impossible for me to complete this
research. I wish to express my biggest gratefulness and love to my family members.
Finally, I wish to say that I treasure very much the friendship of my friends who have
been very supportive in providing all necessary help and advice during the journey of
completing this research.
iv
TABLE OF CONTENT
Abstrak
i
Abstract
ii
Dedication
iii
Acknowledgement
iv
Table of Content
v
List of Tables
viii
List of Figures
ix
CHAPTER 1: INTRODUCTION
1.1
Background
1
1.2
Problem Statement
5
1.3
Research Objective
6
1.4
Scopes of Work
6
1.5
Project Outline
6
CHAPTER 2: LITERATURE REVIEW
2.1
Introduction to Nanostructure
8
2.2
Metal Valve Oxide-iron Oxide: Polymorphs and Properties
10
2.3
Technique to Produce Nanowires
14
2.3.1 Hydrothermal process
14
2.3.2 Sol-gel process
15
2.3.3 Template-assisted electrodeposition
15
2.3.4 Thermal decomposition
16
2.3.5 Thermal oxidation
17
Application of Iron Oxide Nanowires
21
2.4.1 Catalyst
21
2.4
v
2.4.2 Photoelectrochemical cells
22
2.4.3 Photocatalyst
24
CHAPTER 3: METHODOLOGY
3.1
Introduction
27
3.2
Materials
29
3.3
Design of Experiment
29
3.3.1 Substrate preparation and cleaning
29
3.3.2 Thermal oxidation process
30
3.3.3 Thermal oxidation parameter
31
Characterization
31
3.4.1 Morphology characterization
32
3.4
3.4.1.1 Scanning electron microscopy
32
3.4.2 Structural characterization
32
3.4.2.1 X-ray diffraction
32
3.4.2.2 Electron dispersive X-ray
33
3.4.2.3 Raman spectroscopy
34
3.4.3 Photodegradation testing
3.4.3.1 UV lamp chamber
34
34
CHAPTER 4: RESULTS AND DISCUSSIONS
4.1
4.2
4.3
Fe2O3 Nanowires Formation by Thermal Oxidation Process
36
4.1.1 Effect of growth time
37
4.1.2 Effect of sulphuric acid on the morphology of samples
39
Mechanism of Fe2O3 Nanowires Formation
41
4.2.1 Mechanism of Fe2O3 nanostructure in air
41
4.2.2 Mechanism of Fe2O3 nanostructure in air by dropping H2SO4
43
43
X-Ray Diffraction (XRD)
vi
4.4
4.4
4.3.1 Different time effect
44
4.3.2 Influence of H2SO4 on the samples
45
Raman Spectroscopy Analysis
47
4.4.1 Effect of growth time
47
4.4.2 Effect of sulphuric acid (H2SO4)
49
4.4.3 Effect of temperature
49
Photodegradation Testing
51
4.5.1 Mechanism of photodegradation
53
CHAPTER 5: CONCLUSIONS AND RECOMMENDATIONS
5.1
Conclusions
55
5.2
Recommendations
56
REFERENCES
57
vii
LIST OF TABLES
2.1
Physical and Magnetic Properties of Iron Oxide
11
3.1
The List of Materials Used in the Research
29
3.2
List of Changing Parameter
31
4.1
Raman shift of variant phases iron oxide that match Raman shift
of iron oxide nanowires at 300 C, for 60 min
48
4.2
Raman shift of variant phases iron oxide that match Raman shift of
iron oxide nanowires at 300 C, for 180 min
48
4.3
Raman shift of variant phases iron oxide that match Raman shift of
iron oxide nanowires at 300 C, for 300 min
48
4.4
Raman shift of variant phases iron oxide that match Raman shift of
iron oxide nanowires at 180 min, for 300 C
50
4.5
Raman shift of variant phases iron oxide that match Raman shift of
iron oxide nanowires at 180 min, for 500 C
51
Raman shift of variant phases iron oxide that match Raman shift of
iron oxide nanowires at 180 min, for 700 C
51
Sample used for photodegradation of methyl orange
51
4.6
4.7
viii
LIST OF FIGURES
1.1
Morphology of single nanowires
2
1.2
Schematic diagram of single nanowires array
2
1.3
Various synthesized method of nanowires
3
1.4
Application of hematite nanowires
4
1.5
Photocatalytic process
4
2.1
Type of Nanomaterials structure (A) 0D spheres and clusters,
8
(B) 1D nanofibers, wires, and rods, (C) 2Dfilms, plates, and
networks, (D) 3D nanomaterials
2.2
Typical SEM image of different types of 1D nanostructure, (A)
10
nanowires, (B) nanorods, (C) nanotubes, (D) nanobelts, (E)
nanoribbons, and (F) hierarchical nanostructure
2.3
Crystal structure of magnetite (Fe3O4)
12
2.4
Crystal structure of hematite (α–Fe2O3)
13
2.5
Crystal structure of maghemite (γ- Fe2O3)
13
2.6
Schematic diagram of hydrothermal process
14
2.7
Schematic diagram of sol-gel process
15
ix
2.8
Schematic
diagram
of
template-assisted
electrodeposition
16
method
2.9
Schematic diagram of thermal decomposition method
17
2.10
Schematic diagram of thermal oxidation process
18
2.11
Step of iron oxide nanowire growth mechanism: 1)oxygen
19
adsorption, 2)surface oxidization to form nuclei, 3)nuclei
arrangement and 4)formation of nanowires
2.12
The image of Fe substrates oxidize at two different temperatures,
20
2.13
The general catalytic cycle.
22
2.14
The change in activation energy brought about by a catalyst.
22
2.15
Mechanism of phoelectrochemical (PEC) cells
23
2.16
Mechanism of photocatalyst reaction
25
3.1
Flow chart of the experimental work.
28
3.2
Vacuum furnace setup tor thermal oxidation process
30
3.3
Field emission SEM machine
32
3.4
X-Ray diffraction (XRD) machine
33
4)formation of nanowires
(a) 400 C and (b) 600 C and the different type of layer form
The schematic diagram of the thermal oxidation process.
3.5
Equipment set-up for photodegradation of methyl orange
x
35
4.1
FESEM images of Fe2O3 nanowires formed by thermal
37
oxidation process within time (a) 60 min, (b)180 min and (c) 300
min at 300 C in air
4.2
EDX spectra of Fe2O3 nanowires formed
39
4.3
FESEM images of samples synthesized by reaction of H2SO4
40
with Fe at time (a) 60 min, (b) 180 min and (c) 300 min at 300
C in air
4.4
Schematic stress-driven mechanism of Fe2O3 nanowires growth
42
via diffusion
4.5
XRD patterns for Fe substrate formed by thermal oxidation
44
process with time (a) 60 min, (b) 180 min and (c) 300 min at 300
C in air
4.6
XRD patterns for Fe substrate formed by thermal oxidation
45
process with pattern focused region of graph 2Ɵ=20-50
4.7
XRD patterns for Fe substrate formed by thermal oxidation
46
4.8
XRD patterns for Fe substrate formed by thermal oxidation
46
process with time at 300 C in air by dropping H2SO4
process with pattern focused region of graph 2Ɵ=20-50.
4.9
Raman spectrum for iron oxide nanowires formed by thermal
47
4.10
Raman spectrum for iron oxide nanowires formed by thermal
49
oxidation process with time at 300 C in air.
oxidation process with time at 300 C in air. by dropping H2SO4
xi
4.11
Raman spectrum for iron oxide nanowires formed by thermal
50
oxidation process with temperature at 180 min in air
4.12
Methyl orange solution degrade as time exposed to UV light
52
4.13
UV-visible analysis at different time exposed to UV light.
53
xii
CHAPTER 1
INTRODUCTION
This chapter describe the introduction of the project. In this project, thermal
oxidation process was used to form iron oxide nanowires. This chapter also include
background, problem statement, objective, scope and project outline of the study.
1.1
Background
Nanostructure refers to materials system with at least one dimension is in the
range of ~1-100nm. In a nanostructure, electrons are freely move in other dimension
eventhough there are confined in nanoscale dimension. As compared to individual
atom and molecules, the nanostructure is mostly unique.
Nanowires and nanobelts are semi one dimensional nanostructure based
oxides, they have pulled in much consideration lately. They show unordinary optical,
electronic, attractive and mechanical properties as contrasted with those of mass
materials. It is because of the huge surface related deformity starting from the high
surface to volume degrees. Moreover, some paramount properties of one dimensional
nanostructured based oxide are great high temperature steadiness, oxidation safety
and stable electric properties. Thus, it demonstrates their potential basic building
blocks for new classes of environmentally conscious electronics (Yang et al., 2010).
Since the nanowires is studied, some paramount is important which are the control of
morphology, size and growth direction. Figure 1.1 shows the morphology of
nanowire (Hiralal et al., 2008a) while Figure 1.2 shows the schematic diagram of
single nanowire arrays (Rahim et al., 2014). In addition, the different of
1
morphologies get will affect the properties with unique application. A suitable
alignment of substrate is needed for an ensemble of nanowires (Wen et al., 2005).
Figure 1.1: Morphology of single nanowires (Hiralal et al., 2008).
Figure 1.2: Schematic diagram of single nanowire array (Rahim et al., 2014).
Recently, nanowires have been synthesized by several different methods,
such as the hydrothermal process, the template method, the vapour–solid process,
sol–gel technique and thermal decomposition (Liu et al., 2008). Nevertheless,
thermal oxidation in various oxidizing atmosphere is a most simple, cheap and direct
2
procedure to form iron oxide nanowires (Grigorescu et al., 2012) shows in Figure
1.3.
Figure 1.3: Various synthesized method of nanowires.
The growth of nanowires on the surface of iron is depending on the condition.
Under typical condition, layer oxide will be formed, as hematite, magnetite and
wustite. Hematite is formed at outer layer while magnetite as an intermediate layer
and wustite layer form on iron iron substrate. As n-type semiconductor, which has
bandgap 2.1 eV, hematite is environmental friendly, not poisonous, corrosion
resistant and also the cost is low. Figure 1.4 shows the usage of hematite.
3
Figure 1.4: Application of hematite nanowires
Among of these application, one of interesting is as photocatalyst (Figure
1.5). Photocatalytic reactions promoted by aqueous suspensions of nano sized
transition metal oxides have been subject of abundant number of resent research
(Bakardijeva et al., 2007) with the semiconductor performance, iron oxide is use in
solar photoelectrolysis cells. Hematite is a good catalyst for photooxidation of
sulphite. The details on this iron oxide will be reviewed in chapter 2.
Figure 1.5: Photocatalytic process (Ctibor et al., 2013)
4
1.2
Problem Statement
Since the time that Fujishima and Honda reported in 1972, TiO2
photoelectrode methodology is utilized to create hydrogen from water. Ways and
intends to utilize daylight as an essential vitality hotspot for hydrogen fuel era has
been an exceptionally examined point in science and engineering, with a specific end
goal to accomplish an upgraded daylight reaction, materials must have a suitably low
band crevice and ready to part water, and additionally have suitable band edge
positions in respect to the red-ox capability of water. Subsequently, hematite, with
band hole of 2.1 eV has recovered solid examination enthusiasm to be utilized as
terminal water part for hydrogen generation. These are because of the cost, less
advanced yet plentiful materials.
Moreover, because of the looked into that had being carried out, it
demonstrated that, the examination about arrangement of iron oxide nanowires by
utilizing warm oxidation system was very constrained. It is accepted that nanowires
develop from tip while reactant (metal) diffuse by means of the surface from the
metal substrate. However the accurate instrument of development is a long way from
clear. All the more as of late, different gatherings have returned to the spontaneous
development of oxide nanowires by warm oxidation of metallic substrates (Fe, Zn
and Cu), despite the fact that a definite orderly study is needing.
Photocatalytic response advanced by watery suspensions of nano estimated
move metals oxide have been subject plenteous number of exploration (Bakardijeva
et al., 2007). Iron oxide has been concentrated on broadly for utilization in sunlight
based photoelectrolysis cells. Bamba et.al., (2006) considered the photocatalytic
oxidation of a few dangers at TiO2 and Fe2O3, surfaces. They found that TiO2
powder is dynamic photocatalyst for cyanide oxidation, while no oxidation was
watched for Fe2O3. Recently a few studies exhibited the confirmation for photograph
reactant arrangement of OH radicals. The era of OH radicals is attained through the
usage of costly oxidants such ozone and H2O2 often in mix, with or without UV
radiation. Nonetheless, in this theory, the photocatalytic action of iron oxide got by
warm oxidation technique which is this system is basic and immediate method.
5
1.3
Research Objectives
This research is about the formation of iron oxide nanowires and followings
are the objectives for this work:
a) To produce the iron oxide nanowires formed by thermal oxidation
b) To study the mechanism of iron oxide nanowires by thermal oxidation
c) To study the photocatalysis of iron oxide formed by thermal oxidation
1.4
Scopes of Work
This research covered the study on the formation of Fe2O3 nanowires. For the
synthesis of Fe2O3nanowires, thermal oxidation process was selected. For thermal
oxidation process, the effect of temperature, condition on the substrate and time were
studied. Besides, the photocatalytic application was also considered.
Phase and morphology characterization on the Fe2O3 nanowires was examined by
using Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), Electron
Dispersive X-Ray Spectroscopy (EDX), Raman Spectroscopy, UV Visible
Spectrometry and UV lamp chamber.
1.5
Project Outline
This project was conducted to form the iron oxide nanowires structure by
thermal oxidation process. This process was performed in vacuum furnace at
temperature 300 C – 700 C to form the nanowires. The photocatalytic ability of the
formed oxides it tested by using the UV light irradiation.
Chapter one is the introduction for this whole project while in the chapter two
is explain about nanostructure materials, thermal oxidation process and also the
6