HANOI UNIVERSITY OF SCIENCE AND TECHNOLOGY MASTER THESIS FABRICATION OF THE NANO INK BASED ON SnS2 APPLYING FOR GAS SENSOR TO THI NGUYET Nguyet.vn Specialized: SCHOOL OF ENGINEERING PHYSICS Supervisor: Professor. Nguyen Duc Hoa Institute: School of Engineering Physics HANOI, 10/2023 HANOI UNIVERSITY OF SCIENCE AND TECHNOLOGY MASTER THESIS FABRICATION OF THE NANO INK BASED ON SnS2 APPLYING FOR GAS SENSOR TO THI NGUYET Nguyet.vn Specialized: SCHOOL OF ENGINEERING PHYSICS Supervisor: Professor. Nguyen Duc Hoa Signature of Supervisor Institute: School of Engineering Physics HANOI, 10/2023 DECLARATION OF AUTHORSHIP This thesis has been written based on my comprehensive research carried out at the Hanoi University of Science and Technology since I was a pre-graduate student at the School of Engineering Physics, under the supervision of Professor. Nguyen Duc Hoa.
I declare that all the data and results in the thesis are genuine, and were approved to be used in my thesis by my supervisor. The presented results have been never published by other authors. Hanoi, October 2023 Supervisor MSc. Nguyen Duc Hoa To Thi Nguyet ACKNOWLEDGEMENTS First, I would like to express my deep gratitude to my supervisor, Prof.
Nguyen Duc Hoa, for his devotion and inspiring supervision throughout my postgraduate course. I am grateful to Assoc. Nguyen Van Duy, Assoc. Dang Thi Thanh Le, Assoc.
Chu Manh Hung, and Dr. Nguyen Van Toan for their assistance, suggestions, and comments. I am thankful to the Dean of the School of Engineering Physics Prof. Nguyen Huu Lam for his unconditional assistance.
I gratefully acknowledge the Scholarship of Vingroup Innovation Foundation (VINIF) which provided financial support for my research. I also would like to express my special thankfulness to colleagues at Smart Sensor & Device Group at ITIMS for sharing notable experiences during my Master’s course. Eventually, I am genuinely thankful to my family for their endless love and unconditional support. SUMMARY OF THESIS This thesis concentrates on the fabrication and research of gas-sensing properties of layered material to optimize working temperature down to room temperature.
The initial purpose is to generate nanomaterial that could be used for flexible devices. Therefore, in this study, experiment methodology combined with analytical tools, and theoretical models are applied to shed light on the morphology, microstructure, and gas-sensing characteristics of two-dimensional material. In detail, firstly pure layered material (SnS2) and their heterojunction with SnO2 were synthesized via facile hydrothermal method, and the strong effect factors on gas-sensing behavior were investigated deeply. Secondly, the nano-ink solution was carried out by probe ultrasonication to disperse well nanopowders into a solvent which was prepared for ink-jet printing.
Thirdly, the gas sensor devices were fabricated by two technologies including microelectronic technique and ink-jet printing process. Lastly, to clarify the gas-sensing properties of SnS2 and their nanocomposite with SnO2, the model calculation and energy theoretical model are constructed. The results showed that sensors could operate at low temperatures with high response, high selectivity, and good stability. The research of flexible devices based on nano-ink plays a vital role in the development of wearable electronic devices in the future.
Student To Thi Nguyet CONTENTS INTRODUCTION. OVERVIEW OF 2D SnS2 LAYERED MATERIALS AND THEIR HETEROJUNCTION WITH SnO2 FOR GAS-SENSING APPLICATION AND THE FUNDAMENTAL OF THE FLEXIBLE GAS SENSOR TECHNOLOGY. The layered metal dichalcogenides (LMDs) for gas-sensing application. Fundamental of layered metal dichalcogenides and its application in the gas-sensing field.
Overview of the SnS2 materials. SnS2 materials for gas-sensing application. Heterojunction gas sensors. Overview of gas sensor based on heterojunction.
Overview of gas sensor based on heterojunction of SnS2 and semiconductor oxide (SnO2). Gas sensor based on nano-ink. Overview of the low-power consumption gas sensor. Overview of ink-jet printing technique and fabrication nano-ink 24 1.
Overview of the flexible gas sensor based on inkjet printing. Synthesis of the sensing material. Preparation of SnS2 nanoflakes. Preparation of SnO2 nanoparticles – doped SnS2 nanosheets.
Preparation of SnS2-based nano-ink. Fabrication of the gas sensor based on SnS2 material. Conventional technique for SiO2/Si gas sensor. Ink-jet printing on a PET substrate.
Characterization Techniques and gas sensing measurement. Gas sensing measurement. SnS2 NANOFLAKES AND THEIR DECORATING WITH SnO2 NANOPARTICLES FOR NO2 GAS SENSING APPLICATION. NO2 gas sensor based on SnS2 nanoflakes.
Morphology and structure of SnS2 nanoflakes. NO2 gas sensor based on pristine SnS2 nanoflakes. NO2 gas sensors based on heterojunction of SnS2/SnO2. NO2 gas – sensing properties.
SnS2-based nanoink in NO2 gas sensing. SnS2/SnO2 ink formation for inkjet printing. Morphology characterization of SnS2/SnO2 nano-ink. Gas sensing performance of SnS2/SnO2 nano-ink.
77 CONCLUSION AND RECOMMENDATIONS. 84 LIST OF FIGURES Figure 1. The scheme showing the primary application of layered materials [8]. The typical representation of two-dimensional LMDs [9].
The various phases of single–layer and stacked single-layer TMDs (A) 1T phase, (B) ideal 1T phase, (C) distorted 1T phase, (D) 2H phase, and (E) 3R phase [8]. The flexible single-layer MoS2 gas sensor for detecting NO2 sensing performance. Few-layer MoS2 gas sensor with various target gases (NO2, ammonia, formaldehyde, ethanol, acetone, methanol). Structure schematic of SnS2 nanosheets (A) side view, (B) Top view of multilayers [20].
Raman spectra of few-layer 2H-SnS2 (a) Low and high-frequency modes of 5L 2H-SnS2 measure in various wavelengths of LASER, (b) Excitation energy of the A1g modes from 1L to 14L, (c) high-frequency modes of the few-layer 2H-SnS2 using the 523 lasers (d) the Eg mode recorded using the 441. Electronic band structure of SnS2 nanosheets in various layers (a-d), the electron density distribution of conduction band minimum for SnS 2 nanoflakes (e) [22]. SEM images of MoS2/SnO2 heterojunction with different magnifications (a- i) [34]. SEM images of MoSe2 and MoO3/MoSe2 nanocomposite sensors and the sensor response properties at room temperature [36].
Printed, flexible, and organic electronics evolution in 2020 – 2030 [50]. The typical stages in electronic printing process [52]. The ink-based printing technologies are applied in flexible electronic devices [59]. The schematic of continuous inkjet printer (a) and on-demand inkjet printer [61].
Variety configuration of piezo-driven head printing (a) squeeze, (b) shear, (c) bend, (d) push. The graph of ink supply getting the ink to print-head [62]. The MEMs gas sensor based on mesoporous ZnO fabricated by ink-jet printing process [71]. Printed SnO2 gas sensor response to NO2 gas [10.
Schematic of pristine SnS2 nanoflakes by hydrothermal method. The assembly mechanism of SnO2 NPs – doped SnS2 nanoflowers by one-pot reaction. The Inter Digitated Electrodes (IDE) fabrication via microelectronic technology. The drop-casting process of the SnS2 gas sensor.
Testing nano-ink parameters using KiBron Aquapi tensionmeter (A) and DV2T viscometer (B). The DMP-2800 printer for lab-scale printing (A), the IDE electrode designing (B), and gas sensor fabrication using SnS2/SnO2 composite nano-ink printing (C). The schematic diagram of the gas-sensing measuring system. The visualization of detection limit determination.
FESEM images of 2D SnS2 nanoflakes prepared with various molar ratios precursor (A) SS-4, (B) SS-6, and (C) SS-8. XRD patterns of the SS-x product synthesized hydrothermally with different SC(NH2)2/SnCl4 molar ratios at 200oC for 48 h after annealing. SEM images of the prepared SnS2 at temperature of (A-B) 160oC, (C-D) 200oC, and (E-F) 240oC in 24 hours. Note that the left-side has a low-magnification image and right-side exhibit high-magnification images.
SEM images of the prepared SnS2 at temperature of (A-B) 160oC, (C-D) 200oC, and (E-F) 240oC in 48 hours. Note that left-side are low-magnification image and right-side exhibit high-magnification images. XRD patterns of SnS2 products after annealing at 300oC for 2 hours under different hydrothermal conditions. (A) EDS analysis; and (C-D) elemental mapping images of the SnS2 nanoflakes.
(A, B) TEM micrographs of the SnS2 nanoflakes; (C ) HRTEM micrograph, and (D) corresponding SAED patterns of the SnS2 nanoflakes. Raman spectroscopy of the SnS2 nanoflakes (A) and TGA and DTA curve for decomposition of pre-annealing SnS2 nanoflakes. The XPS spectrum of SnS2 (A), High-resolution XPS spectrum of Sn 3d (B), and S 2p. Resistance transients of SnS2 nanoflakes sensors to 5 ppm NO2 at various operating temperatures (A), sensor resistance in air (B), sensor response (C), and response time and recovery time (D) as a function with operating temperatures.
The response transient of the sensor based on different molar ratio of precursor: SS-4 (A), SS-6 (B), and SS-8 (C) to 5 ppm NO2 at the temperature range of 100 – 300oC. Sensor response to NO2 as a function of precursor concentration (D). The resistance curve versus time of SnS2 sensor at different hydrothermal synthesis conditions at 150oC and various NO2 concentration (A), the response as a function of NO2 concentrations (B). The resistance curve versus time of SnS2 sensor at different hydrothermal synthesis conditions at 200oC and various NO2 concentration (A), the response as a function of NO2 concentrations (B).
The resistance curve versus time of SnS2 sensor at different hydrothermal synthesis conditions at optimal temperature and various NO2 concentration (A), the response as a function of NO2 concentrations (B). The correlation of the SnS2 sensor response and concentration at the optimal temperature. Electric noise measurements of SnS2 synthesized in different hydrothermal conditions at 250C during air exposure. Dynamic gas sensing of SnS2−based gas sensor at 250C (A), plot of the response as a function of NO2 gas with different concentrations (0.
Repeatability of the SnS2 sensor (A), Sensing performance of five sensors upon exposure to 1 ppm NO2 at 250 C (B). Top view and side view of the optimized configuration of NO2 gas molecules on the SnS2 surface (A-B) and charge density difference of NO2 (C-D). Charge accumulation and depletion are represented in yellow and blue, respectively. (A) Density of states of isolated NO2 gas and (B) the adsorption systems NO2 – SnS2.
The FESEM images of the obtained SnO2-doped SnS2 nanoflower-like morphology under different magnification. Low magnified (A) and higher magnified (B) TEM image of SnS2/SnO2 nanoflowers. The proper nanoflakes recorded in the fringe of the nanoflower; up inset is the magnified image in marked area by the white rectangular; down is the high-resolution graphic of the nanoflower fringe (C), The high-resolution of layered SnS2 flakes, inset is the corresponding Fast Fourier Transform (FFT) patterns of SnO2 nanoparticles (D), The high-resolution image of the SnS2 nanoflake of marked area in D; right top inset is the FFT patterns of SnS2 hexagonal structure (E), The SEAD patterns of the flake’s surface. Energy-dispersive X-Ray elemental mapping analysis (A) EDX spectrum of SnS2/SnO2, (B-D) Elemental mapping of Sn, S, and O elements respectively.
XRD patterns of the as-prepared SnS2/SnO2 nanoflower and SnS2 nanoflakes (A) and Raman spectroscopy. The TGA and DTA curve of SnS2/SnO2 composite. XPS spectra for the as-synthesized SnS2/SnO2 nanoflowers: (A) survey spectrum, and high-resolution spectra of (B) Sn 3d, (C) S 2p, and (D) O 1s. I-V curve of SnS2/SnO2 sensor (A-B) and the resistance as a function of working temperature in the range of 25 – 250C.
NO2 gas-sensing characteristics of SnS2/SnO2 sensor (A) The transient resistance curve versus time upon exposure to various concentrations of NO2 gas measured at temperature range of 25 – 250C, (B) Response as a function of NO2 concentration measured at different temperatures. The correlation curve of the response of the sensor to NO2 from 0.1 to 1 ppm at room temperature (A), Cyclic response curves of the SnO2/SnS2 sensor toward 1 ppm of NO2 at room temperature. The dynamic resistance of the sensor to 1 ppm NO2 in various relative humidity (40 – 70 %RH) (A), the baseline resistance as a function of the humidity (B), The selectivity of the sensors upon exposure toward 1 ppm NO2 and other interfering gases (1 ppm SO2, 500 ppm, Methanol, Isopropanol, toluene, TEA) at 100oC (C), and the comparison in response between pristine SnS2-based sensor and SnS2/SnO2-based sensor.
