Luận văn fabrication of zn2sno4 nanostructures for gas sensor application chế tạo vật liệu zn2sno4 cấu trúc nano Ứng dụng cho cảm biến khí

Process diagram of synthesizing 7aoSnO¿ nanomalerials wilh different morphological structures by hydrothermal method.. Process diagram of synthesizing 7aoSnO¿ nanomalerials wilh differ

HANOI UNIVERSITY OF SCIENCE AND TECHNOLOGY

MASTER THESIS

Fabrication of Zn2SnO4 nanostructures

for gas sensor application

LAI VAN DUY

Duy LVCA180178@sis.husteduvn

Specialized: Electronic materials

Supervisor: Professor Ph.D Nguyen Due Hoa

Tastitate: 9 International Traimng Tstitule for Materials Science (TTTMS)

TIANOI, 6/2020

HANOI UNIVERSITY OF SCIENCE AND TECHNOLOGY

MASTER THESIS

Fabrication of Zn2SnQ4 nanostructures

for gas sensor application

LAI VAN DUY

Duy LVCA180178@sis-hust.edu.vn

Specialized: Electronic materials

Supervisor: Professor Ph.D Nguyen Duc Hoa Signature of GVHD _

Institute: = International Training Institue for Materials Science (ITIMS)

HFANOI, 6/2020

CONG HOA XA HOI CHU NGHTA VIET NAM

Độc lận — Tự đo— Hạnh phúc

BẢN XÁC NHẬN CHỈNH SỬA LUẬN VĂN THẠC SĨ

lo và tên tác giả luận văn: Lại Văn Duy

Để tài luận văn: Chế tạo vật liên ZnzSnO; cảu trúc nano img dung cho cảm biến

khí

Chuyên ngành: Khoa học vật liệu-VLĐT

Mã số SV: CA180178

Tác giã, Người hướng đẫn khoa hoc va 116i ding châm luận văn xác nhận tác

giả dã sửa chữa, bổ sung luận văn theo biên bản họp Hội dồng ngảy 30/06/2020 với các nội dụng sau:

- Bễ sung chủ thích hình 3.9, 3.10, 3.13

- Các công thức, phương trinh phần ứng được đánh số theo trinh tự

- Bảng danh mục chữ viết tắt sắp xếp theo thứ tự alpha b

- Chit trên trong các hình 3.2, 3.4, 3.6, 3.25 được để ở kich thước lóm hon

- Phân chú thích hình có đâu chấm sau số thứ tự hình

- Chính sửa các lỗi chính tả, hành văn

y 09 tháng 07 năm 2020

CHỦ TỊCH HỘI ĐỒNG

TGS TS Nguyễn Phúc Dương

Number Abbreviations

and symbols

ads

BET CVD

‘TEM VOCs

XRD

ABBREVIATIONS

Meaning

Adsorption Brunauer- Imnet-Teller Chemical Vapour Deposition Fnergy-dispersive X-ray spectroscopy

High Resolution Transmission Electron Microscope

Parts per billion

Parts per million

Rav

Rass Sensitivity

Scanning Electron Microscope

‘Transition Lilectron Microscope

Volatile Organic Compounds

X-ray Diffraction

LIST OF FIGURES

Figure 1.1 VOCs in exhaled breath can be used as biomarkers for diseases

diagnose [47]

Figure 1.2, Crystal structures of zine stannate (4m8nO1) [51] 0

Figure 1.3 Sublattices of vine starmate (79104)

Figure 1.4, Schematic representation of the inverse spinel lattiec of ZmSnO4 [49]

Vignre 1.5 Model explains the n-type semiconductor of Zn SnO4 material [50] Figure 1.6 A schematic diagram of reaction mechanism of SnO2-based sensor Lo

HCHO: (a) in air, (b) in VOCs [73]

Figure 1.7 Schematic energy level diagram of a metal oxide before (a) and after

exposure to a VOCS (b) [43]

Figure 1.8 A schematic of the sensing mechanism of (a) Zn© NPs and (b) ZnO

QDs in air (left) and isoprene (right) [74]

Figure 2.1 Photos of some of the main cquipment using synthesized ZmSnOa

nanomaterials by a hydrothermal method such as thermos flask (1), magnetic

stirrer (2), pH meter (3), centrifugal rotary machine (4) and annealing firmace (5)

Figure 2.2 Process diagram of synthesizing 7aoSnO¿ nanomalerials wilh

different morphological structures by hydrothermal method

Figure 2.3 The process diagram for making sensors on the basis of nano

7mSnOa material by small coating method

Figure 2.4, (A) Gas sensitive measuring system at ITIMS; (3) Diagram of the

gas measuring system by static measurement method

Figure 3.1 SEM image of ZueSnO4 samples synthesized by hydrothermal

method with different hydrothennal temperature: (A, B) 160 °C; (C, D) 180°C;

(F, F) 200°C

Figure 3.2 General diagram of synthetic ZmSnO4 materials with different

morphology according to changes in hydrothermal temperature

Figure 3.3 SEM image of ZmzSnO¿ samples synthesized by hydrothermal

method with different amount of P123 surface-active agent (A, B) 0 g, (C, D)

Number Abbreviations

and symbols

ads

BET CVD

‘TEM VOCs

XRD

ABBREVIATIONS

Meaning

Adsorption Brunauer- Imnet-Teller Chemical Vapour Deposition Fnergy-dispersive X-ray spectroscopy

High Resolution Transmission Electron Microscope

Parts per billion

Parts per million

Rav

Rass Sensitivity

Scanning Electron Microscope

‘Transition Lilectron Microscope

Volatile Organic Compounds

X-ray Diffraction

2 Aims of the thesis

CHAPTER 2 EXPERIMENTAL APPROACH

2.1 The synthesis processes of nanostructured Zm,Sn0, materials with different

morphatogies by hydrothermal method

2.1.1, Rquipment and chemicals

2.1.2 The synthesis process of Zn-SnO, nanostructures with different morphologies

‘by hydrothermal method

2.2, Sensor manufacturing processes

2.3 Morphological and anicrostructure analysis

2.4, Survey of gas sensitivity proper tics

ACKNOWLEDGEMENT

First of all, I would like to expross my greatest gratitude to Prof PhD

Nguyen Duc Hoa for his valuable scicutific ideas, guidance

and support of

favorable conditions for me to complete this thesis His kindness and enthusiast

will be in my heart forever

Simultaneously, T would like to express my sincere thanks (o all staffs of

the Laboratory for Research, Development, and Application of Nanosensors at TTIMS-LIUST has always been enthusiastic about helping, sharing experiences

and suggesting many imporlant ideas for me to carry out the research of (his

thesis Moreover, Ï am also very graleful to my colleagues, PhD students, the

iSensors’ graduated students who have always accompanied and assisted me in twa years of doing my master thesis at ITIMS

Finally I would like to thank all my family, friends and colleagues who have always encouraged and shared me to complete this thesis

SUMMARY OF MASTER THESIS

In this project, we developed high-performance VOC gas sensors for breath

lysis by focusing on the controlled synthesis of nanostructured 7n25nOQ, temary metal oxides to maximize the gas sensitivity To archive the objective, we synthesised hollow structure temary muctal by hydrothermal technique with the

assistance of soft template The thickness of the hollow cells was optimised to

desire the highest VOC response Ry hydrothermal method, the author has

successfully synthesized any nanostructures of ZrSnOq with different

amorphologies AL lhe same Lime, ihe thesis also proves the application potcntial

of ZmSnOy material in the gas sensor VOCs The sensor based on ZmSnO4

materials could detect various VOCs gascs such as acetone, cthanol, and

methanol at low conventzalions of ppb levels with high sensitivily

STUDENT

Lai Van Duy

2 Aims of the thesis

CHAPTER 2 EXPERIMENTAL APPROACH

2.1 The synthesis processes of nanostructured Zm,Sn0, materials with different

morphatogies by hydrothermal method

2.1.1, Rquipment and chemicals

2.1.2 The synthesis process of Zn-SnO, nanostructures with different morphologies

‘by hydrothermal method

2.2, Sensor manufacturing processes

2.3 Morphological and anicrostructure analysis

2.4, Survey of gas sensitivity proper tics

ACKNOWLEDGEMENT

First of all, I would like to expross my greatest gratitude to Prof PhD

Nguyen Duc Hoa for his valuable scicutific ideas, guidance

and support of

favorable conditions for me to complete this thesis His kindness and enthusiast

will be in my heart forever

Simultaneously, T would like to express my sincere thanks (o all staffs of

the Laboratory for Research, Development, and Application of Nanosensors at TTIMS-LIUST has always been enthusiastic about helping, sharing experiences

and suggesting many imporlant ideas for me to carry out the research of (his

thesis Moreover, Ï am also very graleful to my colleagues, PhD students, the

iSensors’ graduated students who have always accompanied and assisted me in twa years of doing my master thesis at ITIMS

Finally I would like to thank all my family, friends and colleagues who have always encouraged and shared me to complete this thesis

SUMMARY OF MASTER THESIS

In this project, we developed high-performance VOC gas sensors for breath

lysis by focusing on the controlled synthesis of nanostructured 7n25nOQ, temary metal oxides to maximize the gas sensitivity To archive the objective, we synthesised hollow structure temary muctal by hydrothermal technique with the

assistance of soft template The thickness of the hollow cells was optimised to

desire the highest VOC response Ry hydrothermal method, the author has

successfully synthesized any nanostructures of ZrSnOq with different

amorphologies AL lhe same Lime, ihe thesis also proves the application potcntial

of ZmSnOy material in the gas sensor VOCs The sensor based on ZmSnO4

materials could detect various VOCs gascs such as acetone, cthanol, and

methanol at low conventzalions of ppb levels with high sensitivily

STUDENT

Lai Van Duy

LIST OF FIGURES

Figure 1.1 VOCs in exhaled breath can be used as biomarkers for diseases

diagnose [47]

Figure 1.2, Crystal structures of zine stannate (4m8nO1) [51] 0

Figure 1.3 Sublattices of vine starmate (79104)

Figure 1.4, Schematic representation of the inverse spinel lattiec of ZmSnO4 [49]

Vignre 1.5 Model explains the n-type semiconductor of Zn SnO4 material [50] Figure 1.6 A schematic diagram of reaction mechanism of SnO2-based sensor Lo

HCHO: (a) in air, (b) in VOCs [73]

Figure 1.7 Schematic energy level diagram of a metal oxide before (a) and after

exposure to a VOCS (b) [43]

Figure 1.8 A schematic of the sensing mechanism of (a) Zn© NPs and (b) ZnO

QDs in air (left) and isoprene (right) [74]

Figure 2.1 Photos of some of the main cquipment using synthesized ZmSnOa

nanomaterials by a hydrothermal method such as thermos flask (1), magnetic

stirrer (2), pH meter (3), centrifugal rotary machine (4) and annealing firmace (5)

Figure 2.2 Process diagram of synthesizing 7aoSnO¿ nanomalerials wilh

different morphological structures by hydrothermal method

Figure 2.3 The process diagram for making sensors on the basis of nano

7mSnOa material by small coating method

Figure 2.4, (A) Gas sensitive measuring system at ITIMS; (3) Diagram of the

gas measuring system by static measurement method

Figure 3.1 SEM image of ZueSnO4 samples synthesized by hydrothermal

method with different hydrothennal temperature: (A, B) 160 °C; (C, D) 180°C;

(F, F) 200°C

Figure 3.2 General diagram of synthetic ZmSnO4 materials with different

morphology according to changes in hydrothermal temperature

Figure 3.3 SEM image of ZmzSnO¿ samples synthesized by hydrothermal

method with different amount of P123 surface-active agent (A, B) 0 g, (C, D)

Figure 3.4 Schematic mechanism of synthosizing ZmSnO; materials with

different, morphology by the concentration of surfactants P123 by hydrothermal

method

Figure 3.5 SEM image of ZmŠnO+ nanomaterial synthesized by hydrothermal

mthod wilh different pH conditions: (A,B) pH 8; {C,D) pH 9; (E, F) pH

10; (G, H) pH = 12; (1, K) pH = 13

Figure 3.6 General điagram of the syrthesis of 7125104 materials with different

morphology according to the pH change of the hydrothermal environment

Ligure 3.7 TM (A-D) images of the synthesized hollow cubic ZmSnO1, Inset

Figure 3.10 XRD pattems of ZngSnO4 with condition pil = 8 and plI =13

hydrothermal temperature of 180 °C/24h atter treatment heat at 580 °C for 2h in

Figure 3.11 Raman and PL spectrum of synthesized Zm2Sn0,

Figure 3.12 BRT spectra of 7m$nOq: (A) - Oelahedron, (B) - Cubic, (C) —

Nanoparticles

Figure 3.13 1-V curve of the sensor (A) -

Nanoparticles measured in air al 450 °C

Figure 3.14 Methanol sensing characteristics of nanoparticles ZmzSnOs

(7.TO_PH8) (A) transient resistance versus lime upon exposure lo different

concentrations of methanol measured at different temperatures, (B) scusor

response as a function of methanol; (3) respon and recovery time of sensor

Figure 3.15 Methanol sensing characteristics of hollow cưồic ZzuSnO¿

(ZYOP5_PH8): (A) transient resistance versus time upon exposure to different

concentrations of methanol measured at different temperatures; (B) sensor

response as a unction of methanol, (C) respon and recovery lime of sensor

Ligure 3.16 Methanol sensing, characteristics of hollow octahedron ZmSn0s

(ZTOPS PII): (A) transient resistance versus time upon exposure to different

ĐỂ TÀI LUẬN VĂN Chế tạo vật liệu #2nsSnŒx câu trúc nano ứng dụng cho cảm biển khí Học viên: Lại Văn Duy

Chuyên ngành: Khoa học vật liệu-VI ĐT

Giáo viên hướng dân

(Kỹ và ghỉ rõ họ tên)

GS T8 Nguyễn Đức Hòa

LIST OF FIGURES

Figure 1.1 VOCs in exhaled breath can be used as biomarkers for diseases

diagnose [47]

Figure 1.2, Crystal structures of zine stannate (4m8nO1) [51] 0

Figure 1.3 Sublattices of vine starmate (79104)

Figure 1.4, Schematic representation of the inverse spinel lattiec of ZmSnO4 [49]

Vignre 1.5 Model explains the n-type semiconductor of Zn SnO4 material [50] Figure 1.6 A schematic diagram of reaction mechanism of SnO2-based sensor Lo

HCHO: (a) in air, (b) in VOCs [73]

Figure 1.7 Schematic energy level diagram of a metal oxide before (a) and after

exposure to a VOCS (b) [43]

Figure 1.8 A schematic of the sensing mechanism of (a) Zn© NPs and (b) ZnO

QDs in air (left) and isoprene (right) [74]

Figure 2.1 Photos of some of the main cquipment using synthesized ZmSnOa

nanomaterials by a hydrothermal method such as thermos flask (1), magnetic

stirrer (2), pH meter (3), centrifugal rotary machine (4) and annealing firmace (5)

Figure 2.2 Process diagram of synthesizing 7aoSnO¿ nanomalerials wilh

different morphological structures by hydrothermal method

Figure 2.3 The process diagram for making sensors on the basis of nano

7mSnOa material by small coating method

Figure 2.4, (A) Gas sensitive measuring system at ITIMS; (3) Diagram of the

gas measuring system by static measurement method

Figure 3.1 SEM image of ZueSnO4 samples synthesized by hydrothermal

method with different hydrothennal temperature: (A, B) 160 °C; (C, D) 180°C;

(F, F) 200°C

Figure 3.2 General diagram of synthetic ZmSnO4 materials with different

morphology according to changes in hydrothermal temperature

Figure 3.3 SEM image of ZmzSnO¿ samples synthesized by hydrothermal

method with different amount of P123 surface-active agent (A, B) 0 g, (C, D)

LIST OF FIGURES

Figure 1.1 VOCs in exhaled breath can be used as biomarkers for diseases

diagnose [47]

Figure 1.2, Crystal structures of zine stannate (4m8nO1) [51] 0

Figure 1.3 Sublattices of vine starmate (79104)

Figure 1.4, Schematic representation of the inverse spinel lattiec of ZmSnO4 [49]

Vignre 1.5 Model explains the n-type semiconductor of Zn SnO4 material [50] Figure 1.6 A schematic diagram of reaction mechanism of SnO2-based sensor Lo

HCHO: (a) in air, (b) in VOCs [73]

Figure 1.7 Schematic energy level diagram of a metal oxide before (a) and after

exposure to a VOCS (b) [43]

Figure 1.8 A schematic of the sensing mechanism of (a) Zn© NPs and (b) ZnO

QDs in air (left) and isoprene (right) [74]

Figure 2.1 Photos of some of the main cquipment using synthesized ZmSnOa

nanomaterials by a hydrothermal method such as thermos flask (1), magnetic

stirrer (2), pH meter (3), centrifugal rotary machine (4) and annealing firmace (5)

Figure 2.2 Process diagram of synthesizing 7aoSnO¿ nanomalerials wilh

different morphological structures by hydrothermal method

Figure 2.3 The process diagram for making sensors on the basis of nano

7mSnOa material by small coating method

Figure 2.4, (A) Gas sensitive measuring system at ITIMS; (3) Diagram of the

gas measuring system by static measurement method

Figure 3.1 SEM image of ZueSnO4 samples synthesized by hydrothermal

method with different hydrothennal temperature: (A, B) 160 °C; (C, D) 180°C;

(F, F) 200°C

Figure 3.2 General diagram of synthetic ZmSnO4 materials with different

morphology according to changes in hydrothermal temperature

Figure 3.3 SEM image of ZmzSnO¿ samples synthesized by hydrothermal

method with different amount of P123 surface-active agent (A, B) 0 g, (C, D)

CHAPTER3 RESULTS AND DISCUSSION =-

3.14, Caystal structure of synthesized Zn:SuO, materials

32 Gas sensing propertics of Zn:SnO, matcrials with different morphological

3.2.2 ihanol gus-sensing properlies of the [abricaled sensors

3.2.3 Acetone gas-sensing properties of the fabricated sensors

Figure 3.4 Schematic mechanism of synthosizing ZmSnO; materials with

different, morphology by the concentration of surfactants P123 by hydrothermal

method

Figure 3.5 SEM image of ZmŠnO+ nanomaterial synthesized by hydrothermal

mthod wilh different pH conditions: (A,B) pH 8; {C,D) pH 9; (E, F) pH

10; (G, H) pH = 12; (1, K) pH = 13

Figure 3.6 General điagram of the syrthesis of 7125104 materials with different

morphology according to the pH change of the hydrothermal environment

Ligure 3.7 TM (A-D) images of the synthesized hollow cubic ZmSnO1, Inset

Figure 3.10 XRD pattems of ZngSnO4 with condition pil = 8 and plI =13

hydrothermal temperature of 180 °C/24h atter treatment heat at 580 °C for 2h in

Figure 3.11 Raman and PL spectrum of synthesized Zm2Sn0,

Figure 3.12 BRT spectra of 7m$nOq: (A) - Oelahedron, (B) - Cubic, (C) —

Nanoparticles

Figure 3.13 1-V curve of the sensor (A) -

Nanoparticles measured in air al 450 °C

Figure 3.14 Methanol sensing characteristics of nanoparticles ZmzSnOs

(7.TO_PH8) (A) transient resistance versus lime upon exposure lo different

concentrations of methanol measured at different temperatures, (B) scusor

response as a function of methanol; (3) respon and recovery time of sensor

Figure 3.15 Methanol sensing characteristics of hollow cưồic ZzuSnO¿

(ZYOP5_PH8): (A) transient resistance versus time upon exposure to different

concentrations of methanol measured at different temperatures; (B) sensor

response as a unction of methanol, (C) respon and recovery lime of sensor

Ligure 3.16 Methanol sensing, characteristics of hollow octahedron ZmSn0s

(ZTOPS PII): (A) transient resistance versus time upon exposure to different

Figure 3.4 Schematic mechanism of synthosizing ZmSnO; materials with

different, morphology by the concentration of surfactants P123 by hydrothermal

method

Figure 3.5 SEM image of ZmŠnO+ nanomaterial synthesized by hydrothermal

mthod wilh different pH conditions: (A,B) pH 8; {C,D) pH 9; (E, F) pH

10; (G, H) pH = 12; (1, K) pH = 13

Figure 3.6 General điagram of the syrthesis of 7125104 materials with different

morphology according to the pH change of the hydrothermal environment

Ligure 3.7 TM (A-D) images of the synthesized hollow cubic ZmSnO1, Inset

Figure 3.10 XRD pattems of ZngSnO4 with condition pil = 8 and plI =13

hydrothermal temperature of 180 °C/24h atter treatment heat at 580 °C for 2h in

Figure 3.11 Raman and PL spectrum of synthesized Zm2Sn0,

Figure 3.12 BRT spectra of 7m$nOq: (A) - Oelahedron, (B) - Cubic, (C) —

Nanoparticles

Figure 3.13 1-V curve of the sensor (A) -

Nanoparticles measured in air al 450 °C

Figure 3.14 Methanol sensing characteristics of nanoparticles ZmzSnOs

(7.TO_PH8) (A) transient resistance versus lime upon exposure lo different

concentrations of methanol measured at different temperatures, (B) scusor

response as a function of methanol; (3) respon and recovery time of sensor

Figure 3.15 Methanol sensing characteristics of hollow cưồic ZzuSnO¿

(ZYOP5_PH8): (A) transient resistance versus time upon exposure to different

concentrations of methanol measured at different temperatures; (B) sensor

response as a unction of methanol, (C) respon and recovery lime of sensor

Ligure 3.16 Methanol sensing, characteristics of hollow octahedron ZmSn0s

(ZTOPS PII): (A) transient resistance versus time upon exposure to different

ĐỂ TÀI LUẬN VĂN Chế tạo vật liệu #2nsSnŒx câu trúc nano ứng dụng cho cảm biển khí Học viên: Lại Văn Duy

Chuyên ngành: Khoa học vật liệu-VI ĐT

Giáo viên hướng dân

(Kỹ và ghỉ rõ họ tên)

GS T8 Nguyễn Đức Hòa

Number Abbreviations

and symbols

ads

BET CVD

‘TEM VOCs

XRD

ABBREVIATIONS

Meaning

Adsorption Brunauer- Imnet-Teller Chemical Vapour Deposition Fnergy-dispersive X-ray spectroscopy

High Resolution Transmission Electron Microscope

Parts per billion

Parts per million

Rav

Rass Sensitivity

Scanning Electron Microscope

‘Transition Lilectron Microscope

Volatile Organic Compounds

X-ray Diffraction

Figure 3.4 Schematic mechanism of synthosizing ZmSnO; materials with

different, morphology by the concentration of surfactants P123 by hydrothermal

method

Figure 3.5 SEM image of ZmŠnO+ nanomaterial synthesized by hydrothermal

mthod wilh different pH conditions: (A,B) pH 8; {C,D) pH 9; (E, F) pH

10; (G, H) pH = 12; (1, K) pH = 13

Figure 3.6 General điagram of the syrthesis of 7125104 materials with different

morphology according to the pH change of the hydrothermal environment

Ligure 3.7 TM (A-D) images of the synthesized hollow cubic ZmSnO1, Inset

Figure 3.10 XRD pattems of ZngSnO4 with condition pil = 8 and plI =13

hydrothermal temperature of 180 °C/24h atter treatment heat at 580 °C for 2h in

Figure 3.11 Raman and PL spectrum of synthesized Zm2Sn0,

Figure 3.12 BRT spectra of 7m$nOq: (A) - Oelahedron, (B) - Cubic, (C) —

Nanoparticles

Figure 3.13 1-V curve of the sensor (A) -

Nanoparticles measured in air al 450 °C

Figure 3.14 Methanol sensing characteristics of nanoparticles ZmzSnOs

(7.TO_PH8) (A) transient resistance versus lime upon exposure lo different

concentrations of methanol measured at different temperatures, (B) scusor

response as a function of methanol; (3) respon and recovery time of sensor

Figure 3.15 Methanol sensing characteristics of hollow cưồic ZzuSnO¿

(ZYOP5_PH8): (A) transient resistance versus time upon exposure to different

concentrations of methanol measured at different temperatures; (B) sensor

response as a unction of methanol, (C) respon and recovery lime of sensor

Ligure 3.16 Methanol sensing, characteristics of hollow octahedron ZmSn0s

(ZTOPS PII): (A) transient resistance versus time upon exposure to different

ACKNOWLEDGEMENT

First of all, I would like to expross my greatest gratitude to Prof PhD

Nguyen Duc Hoa for his valuable scicutific ideas, guidance

and support of

favorable conditions for me to complete this thesis His kindness and enthusiast

will be in my heart forever

Simultaneously, T would like to express my sincere thanks (o all staffs of

the Laboratory for Research, Development, and Application of Nanosensors at TTIMS-LIUST has always been enthusiastic about helping, sharing experiences

and suggesting many imporlant ideas for me to carry out the research of (his

thesis Moreover, Ï am also very graleful to my colleagues, PhD students, the

iSensors’ graduated students who have always accompanied and assisted me in twa years of doing my master thesis at ITIMS

Finally I would like to thank all my family, friends and colleagues who have always encouraged and shared me to complete this thesis

SUMMARY OF MASTER THESIS

In this project, we developed high-performance VOC gas sensors for breath

lysis by focusing on the controlled synthesis of nanostructured 7n25nOQ, temary metal oxides to maximize the gas sensitivity To archive the objective, we synthesised hollow structure temary muctal by hydrothermal technique with the

assistance of soft template The thickness of the hollow cells was optimised to

desire the highest VOC response Ry hydrothermal method, the author has

successfully synthesized any nanostructures of ZrSnOq with different

amorphologies AL lhe same Lime, ihe thesis also proves the application potcntial

of ZmSnOy material in the gas sensor VOCs The sensor based on ZmSnO4

materials could detect various VOCs gascs such as acetone, cthanol, and

methanol at low conventzalions of ppb levels with high sensitivily

STUDENT

Lai Van Duy

CHAPTER3 RESULTS AND DISCUSSION =-

3.14, Caystal structure of synthesized Zn:SuO, materials

32 Gas sensing propertics of Zn:SnO, matcrials with different morphological

3.2.2 ihanol gus-sensing properlies of the [abricaled sensors

3.2.3 Acetone gas-sensing properties of the fabricated sensors

CHAPTER3 RESULTS AND DISCUSSION =-

3.14, Caystal structure of synthesized Zn:SuO, materials

32 Gas sensing propertics of Zn:SnO, matcrials with different morphological

3.2.2 ihanol gus-sensing properlies of the [abricaled sensors

3.2.3 Acetone gas-sensing properties of the fabricated sensors

ĐỂ TÀI LUẬN VĂN Chế tạo vật liệu #2nsSnŒx câu trúc nano ứng dụng cho cảm biển khí Học viên: Lại Văn Duy

Chuyên ngành: Khoa học vật liệu-VI ĐT

Giáo viên hướng dân

(Kỹ và ghỉ rõ họ tên)

GS T8 Nguyễn Đức Hòa

ĐỂ TÀI LUẬN VĂN Chế tạo vật liệu #2nsSnŒx câu trúc nano ứng dụng cho cảm biển khí Học viên: Lại Văn Duy

Chuyên ngành: Khoa học vật liệu-VI ĐT

Giáo viên hướng dân

(Kỹ và ghỉ rõ họ tên)

GS T8 Nguyễn Đức Hòa

ĐỂ TÀI LUẬN VĂN Chế tạo vật liệu #2nsSnŒx câu trúc nano ứng dụng cho cảm biển khí Học viên: Lại Văn Duy

Chuyên ngành: Khoa học vật liệu-VI ĐT

Giáo viên hướng dân

(Kỹ và ghỉ rõ họ tên)

GS T8 Nguyễn Đức Hòa

Number Abbreviations

and symbols

ads

BET CVD

‘TEM VOCs

XRD

ABBREVIATIONS

Meaning

Adsorption Brunauer- Imnet-Teller Chemical Vapour Deposition Fnergy-dispersive X-ray spectroscopy

High Resolution Transmission Electron Microscope

Parts per billion

Parts per million

Rav

Rass Sensitivity

Scanning Electron Microscope

‘Transition Lilectron Microscope

Volatile Organic Compounds

X-ray Diffraction

CHAPTER3 RESULTS AND DISCUSSION =-

3.14, Caystal structure of synthesized Zn:SuO, materials

32 Gas sensing propertics of Zn:SnO, matcrials with different morphological

3.2.2 ihanol gus-sensing properlies of the [abricaled sensors

3.2.3 Acetone gas-sensing properties of the fabricated sensors

2 Aims of the thesis

CHAPTER 2 EXPERIMENTAL APPROACH

2.1 The synthesis processes of nanostructured Zm,Sn0, materials with different

morphatogies by hydrothermal method

2.1.1, Rquipment and chemicals

2.1.2 The synthesis process of Zn-SnO, nanostructures with different morphologies

‘by hydrothermal method

2.2, Sensor manufacturing processes

2.3 Morphological and anicrostructure analysis

2.4, Survey of gas sensitivity proper tics

CHAPTER3 RESULTS AND DISCUSSION =-

3.14, Caystal structure of synthesized Zn:SuO, materials

32 Gas sensing propertics of Zn:SnO, matcrials with different morphological

3.2.2 ihanol gus-sensing properlies of the [abricaled sensors

3.2.3 Acetone gas-sensing properties of the fabricated sensors

CHAPTER3 RESULTS AND DISCUSSION =-

3.14, Caystal structure of synthesized Zn:SuO, materials

32 Gas sensing propertics of Zn:SnO, matcrials with different morphological

3.2.2 ihanol gus-sensing properlies of the [abricaled sensors

3.2.3 Acetone gas-sensing properties of the fabricated sensors

CHAPTER3 RESULTS AND DISCUSSION =-

3.14, Caystal structure of synthesized Zn:SuO, materials

32 Gas sensing propertics of Zn:SnO, matcrials with different morphological

3.2.2 ihanol gus-sensing properlies of the [abricaled sensors

3.2.3 Acetone gas-sensing properties of the fabricated sensors

LIST OF FIGURES

Figure 1.1 VOCs in exhaled breath can be used as biomarkers for diseases

diagnose [47]

Figure 1.2, Crystal structures of zine stannate (4m8nO1) [51] 0

Figure 1.3 Sublattices of vine starmate (79104)

Figure 1.4, Schematic representation of the inverse spinel lattiec of ZmSnO4 [49]

Vignre 1.5 Model explains the n-type semiconductor of Zn SnO4 material [50] Figure 1.6 A schematic diagram of reaction mechanism of SnO2-based sensor Lo

HCHO: (a) in air, (b) in VOCs [73]

Figure 1.7 Schematic energy level diagram of a metal oxide before (a) and after

exposure to a VOCS (b) [43]

Figure 1.8 A schematic of the sensing mechanism of (a) Zn© NPs and (b) ZnO

QDs in air (left) and isoprene (right) [74]

Figure 2.1 Photos of some of the main cquipment using synthesized ZmSnOa

nanomaterials by a hydrothermal method such as thermos flask (1), magnetic

stirrer (2), pH meter (3), centrifugal rotary machine (4) and annealing firmace (5)

Figure 2.2 Process diagram of synthesizing 7aoSnO¿ nanomalerials wilh

different morphological structures by hydrothermal method

Figure 2.3 The process diagram for making sensors on the basis of nano

7mSnOa material by small coating method

Figure 2.4, (A) Gas sensitive measuring system at ITIMS; (3) Diagram of the

gas measuring system by static measurement method

Figure 3.1 SEM image of ZueSnO4 samples synthesized by hydrothermal

method with different hydrothennal temperature: (A, B) 160 °C; (C, D) 180°C;

(F, F) 200°C

Figure 3.2 General diagram of synthetic ZmSnO4 materials with different

morphology according to changes in hydrothermal temperature

Figure 3.3 SEM image of ZmzSnO¿ samples synthesized by hydrothermal

method with different amount of P123 surface-active agent (A, B) 0 g, (C, D)

ACKNOWLEDGEMENT

First of all, I would like to expross my greatest gratitude to Prof PhD

Nguyen Duc Hoa for his valuable scicutific ideas, guidance

and support of

favorable conditions for me to complete this thesis His kindness and enthusiast

will be in my heart forever

Simultaneously, T would like to express my sincere thanks (o all staffs of

the Laboratory for Research, Development, and Application of Nanosensors at TTIMS-LIUST has always been enthusiastic about helping, sharing experiences

and suggesting many imporlant ideas for me to carry out the research of (his

thesis Moreover, Ï am also very graleful to my colleagues, PhD students, the

iSensors’ graduated students who have always accompanied and assisted me in twa years of doing my master thesis at ITIMS

Finally I would like to thank all my family, friends and colleagues who have always encouraged and shared me to complete this thesis

SUMMARY OF MASTER THESIS

In this project, we developed high-performance VOC gas sensors for breath

lysis by focusing on the controlled synthesis of nanostructured 7n25nOQ, temary metal oxides to maximize the gas sensitivity To archive the objective, we synthesised hollow structure temary muctal by hydrothermal technique with the

assistance of soft template The thickness of the hollow cells was optimised to

desire the highest VOC response Ry hydrothermal method, the author has

successfully synthesized any nanostructures of ZrSnOq with different

amorphologies AL lhe same Lime, ihe thesis also proves the application potcntial

of ZmSnOy material in the gas sensor VOCs The sensor based on ZmSnO4

materials could detect various VOCs gascs such as acetone, cthanol, and

methanol at low conventzalions of ppb levels with high sensitivily

STUDENT

Lai Van Duy

LIST OF FIGURES

Figure 1.1 VOCs in exhaled breath can be used as biomarkers for diseases

diagnose [47]

Figure 1.2, Crystal structures of zine stannate (4m8nO1) [51] 0

Figure 1.3 Sublattices of vine starmate (79104)

Figure 1.4, Schematic representation of the inverse spinel lattiec of ZmSnO4 [49]

Vignre 1.5 Model explains the n-type semiconductor of Zn SnO4 material [50] Figure 1.6 A schematic diagram of reaction mechanism of SnO2-based sensor Lo

HCHO: (a) in air, (b) in VOCs [73]

Figure 1.7 Schematic energy level diagram of a metal oxide before (a) and after

exposure to a VOCS (b) [43]

Figure 1.8 A schematic of the sensing mechanism of (a) Zn© NPs and (b) ZnO

QDs in air (left) and isoprene (right) [74]

Figure 2.1 Photos of some of the main cquipment using synthesized ZmSnOa

nanomaterials by a hydrothermal method such as thermos flask (1), magnetic

stirrer (2), pH meter (3), centrifugal rotary machine (4) and annealing firmace (5)

Figure 2.2 Process diagram of synthesizing 7aoSnO¿ nanomalerials wilh

different morphological structures by hydrothermal method

Figure 2.3 The process diagram for making sensors on the basis of nano

7mSnOa material by small coating method

Figure 2.4, (A) Gas sensitive measuring system at ITIMS; (3) Diagram of the

gas measuring system by static measurement method

Figure 3.1 SEM image of ZueSnO4 samples synthesized by hydrothermal

method with different hydrothennal temperature: (A, B) 160 °C; (C, D) 180°C;

(F, F) 200°C

Figure 3.2 General diagram of synthetic ZmSnO4 materials with different

morphology according to changes in hydrothermal temperature

Figure 3.3 SEM image of ZmzSnO¿ samples synthesized by hydrothermal

method with different amount of P123 surface-active agent (A, B) 0 g, (C, D)

Number Abbreviations

and symbols

ads

BET CVD

‘TEM VOCs

XRD

ABBREVIATIONS

Meaning

Adsorption Brunauer- Imnet-Teller Chemical Vapour Deposition Fnergy-dispersive X-ray spectroscopy

High Resolution Transmission Electron Microscope

Parts per billion

Parts per million

Rav

Rass Sensitivity

Scanning Electron Microscope

‘Transition Lilectron Microscope

Volatile Organic Compounds

X-ray Diffraction