STANUM DIOXIDE (SnO 2 ) DOPED POLYANILINE (n-C 6 H 5 NH 2 ) THIN FILM AS THE MATERIALS FOR LIQUEFIED PETROLEUM GAS (LPG) AND HYDROGEN (H 2 ) GAS SENSOR NUR AMIRUL MUKMIN ENDUT Submitted to the Faculty of Chemical & Natural Resources Engineering in partially fulfillment of the requirements for the degree of Bachelor of Chemical Engineering (Gas Technology) Faculty of Chemical & Natural Resources Engineering Universiti Malaysia Pahang APRIL 2009
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STANUM DIOXIDE (SnO2) DOPED POLYANILINE (n-C6H5NH2) THIN FILM
AS THE MATERIALS FOR LIQUEFIED PETROLEUM GAS (LPG) AND
HYDROGEN (H2) GAS SENSOR
NUR AMIRUL MUKMIN ENDUT
Submitted to the Faculty of Chemical & Natural Resources Engineering in partially
fulfillment of the requirements for the degree of Bachelor of Chemical Engineering (Gas
Technology)
Faculty of Chemical & Natural Resources Engineering
Universiti Malaysia Pahang
APRIL 2009
iv
AKNOWLEDGEMENT
First of all, I would like to express my heartily gratitude to my research
supervisor, Mr. Azizan Bin Ramli for his guidance, advices, efforts, supervision and
enthusiasm given throughout for the progress of this research.
In preparing this thesis, I was in contact with many people, lecturers, and
training engineers. They have contributed towards my understanding and thoughts.
Without their continued support and interest, this thesis would not have been the same
as presented here.
I would like to express my sincere appreciation to my parents for their support to
me all this year. Without them, I would not be able to complete this research. Besides
that, I would like to thank my course mates and my friends especially my housemate
E32 for their help, assistance and support and encouragement.
v
ABSTRACT
Gas sensor is a device which detects the presence of gas. The choice in selecting
gas sensor was based on their sensitivity, selectivity and stability. The objectives of this
research are to study stanum dioxide (SnO2) doped polyaniline (n-C6H5NH2) as new
sensing materials for LPG and H2 gas sensor at room temperature and to study the gas
(LPG and H2) sensing characteristic to the sensor at room temperature. This research
focused on the effect of doping ratio of sensor material, gas flow time to the gas
response and response time of the sensor. Sensors are prepared using two deposition
methods which are chemical bath deposition (CBD) for fabrication of SnO2 and
electrodeposition (ED) for fabrication of polyaniline. In this experimental work 3
sensors with different doping ratio (polyaniline: SnO2) were prepared which is 70:30,
50:50 and 30:70. The gas response most influenced by the doping ratio. From the result
the highest gas response (55%) achieved by sensor with doping ratio 70:30 for LPG
contrast with highest gas response (50%) for H2 achieved by sensor with doping ratio
30:70. The response time most influenced by gas flow time. High flow time means the
concentration is high. Based on experimental result at range 10s to 40s of gas flow time,
the 40s gas flow time show the short time response for all sensor.
vi
ABSTRAK
Pengesan gas adalah sebuah alat yang mengesan kehadiran gas. Pilihan dalam
pemilihan pengesan gas telah didasarkan kepekaan mereka, pemilihan terhadap
sesetengah gas dan kestabilan. Objektif bagi penyelidikan ini adalah mengkaji stanum
dioksida (SnO2) ‘doped’ polyaniline (n-C6H5NH2) sebagai satu komposisi baru bagi alat
pengesan gas untuk gas LPG dan H2 pada suhu bilik dan untuk mengkaji sifat-sifat
pengesan gas terhadap (LPG Dan H2) pada suhu bilik. Kajian ini memfokuskan pada
kesan nisbah campuran atau ‘doping’ antara SnO2 dan polyaniline dan masa aliran gas
terhadap respon gas dan masa respon oleh pengesan tersebut. Pengesan disediakan pada
tiga nisbah campuran iaitu (polyaniline: SnO2) 70:30, 50:50 dan 30:70. Kaedah yang
digunakan adalah kaedah pemendakan iaitu ‘chemical bath deposition’(CBD) dan
‘electrodeposition’(ED). Daripada eksperimen, respon gas sangat dipengaruhi oleh
nisbah campuran atau ‘doping’ antara SnO2 dan polyaniline (polyaniline: SnO2).
Pengesan dengan nisbah 70:30 mencapai respon tertinggi (55%) bagi gas LPG berlainan
pula bagi gas H2 yang mana pengesan dengan nisbah 30:70 mencapai respon tertinggi
(50%). Masa respon gas pula dipengaruhi oleh masa aliran gas. semakin tinggi masa
aliran gas bermakna kepekatan gas juga semakin tinggi. Ini dibuktikan dari keputusan
eksperimen yang mana daripada julat 10s hingga 40s aliran gas, masa respon pada 40s
aliran gas memberikan masa respon yang paling pantas untuk semua pengesan.
vii
TABLE OF CONTENT
CHAPTER TITLE PAGE
DECLARATION ii
DEDICATION iii
AKNOWLEDGEMENT iv
ABSTRACT v
ABSTRAK vi
TABLE OF CONTENT vii
LIST OF TABLES x
LIST OF FIGURES xi
LIST OF ABBREVIATIONS xiii
LIST OF APPENDICES xiv
1 INTRODUCTION
1.1 Research Background 1
1.1.1 Gas Sensor 1
1.1.2 Working Principle 2
1.1.3 Material/composition 3
viii
1.2 Problem Statement 4
1.3 Objectives 5
1.4 Scope of Study 5
2 LITERATURE REVIEW
2.1 Gas Sensor 6
2.2 Stanum Dioxide 8
2.3 Polyaniline 11
2.4 Chemical Bath Deposition(CBD) 13
2.5 Electrodeposition (ED) 14
2.6 Liquefied Petroleum Gas 15
2.7 Hydrogen 18
2.8 Summary 20
3 METHODOLOGY
3.1 Introduction 22
3.2 Experimental Details
3.2.1 Fabrication of SnO2 Doped Polyaniline 23
Heterojunction.
3.2.2 Fabrication of Gas Sensor Unit 26
3.2.3 LPG and H2 Sensing Properties of 27
p-poyaniline/n-SnO2 Heterojunction
3.3 Outline/flow Chart of Methodology 30
ix
4 RESULT AND DISCUSSION
4.1 Introduction 31
4.2 Sensing Properties of p-Polyaniline/n-SnO2 32
Sensor for LPG
4.2.1 Effect of Doping Ratio of 32
p-Polyaniline/n-SnO2
4.2.1.1 Gas Response 32
4.2.1.2 Response time 35
4.2.2 Effect of Gas Flow Time 37
4.2.2.1 Gas Response 37
4.2.2.2 Response Time 40
4.3 Sensing Properties of p-Polyaniline/n-SnO2 40
Sensor for H2
4.3.1 Effect of Doping Ratio 40
p-Polyaniline/n-SnO2
4.3.1.1 Gas Response 40
4.3.1.2 Response Time 44
4.3.2 Effect of Gas Flow Time 46
4.3.2.1 Gas Response 46
4.3.2.2 Response Time 49
5 CONCLUSION AND RECOMMENDATIONS
5.1 Conclusions 50
5.2 Recommendations 52
REFERENCES 53
APPENDIX A-D 57-60
x
LIST OF TABLES
TABLE NO TITLE PAGE
2.1 Chemical and physical properties of SnO2 9
2.2 Properties of LPG 15
2.3 Health effect and first aid steps of LPG 16
2.4 Properties of hydrogen 18
2.5 Health effect and first aid steps of H2 19
2.6 Summary of literature review 20
3.1 Experimental material and reagents 23
4.1 Result of doping ratio (polyaniline: SnO2) 70:30 32
for LPG
4.2 Result of doping ratio (polyaniline: SnO2) 50:50 for LPG 33
4.3 Result of doping ratio (polyaniline: SnO2) 30:70 for LPG 33
4.4 Optimum gas response for LPG 34
4.5 Result of doping ratio (polyaniline: SnO2) 70:30 for H2 41
4.6 Result of doping ratio (polyaniline: SnO2) 50:50 for H2 41
4.7 Result of doping ratio (polyaniline: SnO2) 30:70 for H2 42
4.8 Optimum gas response for H2 43
xi
LIST OF FIGURES
FIGURE NO TITLE PAGE
2.1 Example of gas sensor in market 7
2.2 SEM image for SnO2 (B. Thomas et.al. 2008) 8
2.3 SEM image of polyaniline.(Dawale et.al. 2008) 12
2.4 Configuration of chemical bath deposition method 13
2.5 Configuration of electrodeposition method 14
3.1 CBD method for fabrication SnO2 thin film 24
3.2 ED method for fabrication polyaniline thin film 25