Surface Functionalization of MXene with Amphiphilic Alkoxysilane Oligomers Toward Multifunctional Printable Inks for Energy Device Applications = 에너지 소자 응용을 위한 다기능 인쇄형 잉크 개발을 목표로 한 양친매성 알콕시실란 올리고머를 이용한 MXene의 표면 기능화

다국어 초록 (Multilingual Abstract)

MXenes, a family of two-dimensional transition metal carbides and nitrides, exhibit exceptional electrical conductivity, high surface area, and versatile electrochemical properties, making them promising candidates for a wide range of applications, including energy storage, energy harvesting, sensing, catalysis, and electronic devices. However, their practical use is often limited by poor dispersibility in solvents, easily to oxidation, and weak adhesion to various substrates, which typically necessitate polymeric binders or conductive additives. In this thesis, amphiphilic alkoxysilane functionalization was developed to overcome these limitations. The surface-modified MXene exhibited stable dispersion across diverse solvents and strong adhesion on flexible substrates, enabling facile integration into complex device architectures. The modified MXene was demonstrated in three representative platforms: (i) as symmetric supercapacitor electrodes, achieving high capacitance and excellent cycling stability; (ii) as asymmetric microsupercapacitors fabricated via additive-free direct EHD printing; and (iii) in triboelectric nanogenerators (TENGs), where the well-dispersed MXene within a PVDF matrix promoted highly ordered β-phase crystallinity and enhanced charge trapping, thereby improving energy-harvesting efficiency. Overall, this thesis demonstrates a versatile interfacial engineering strategy for MXenes, addressing key limitations in dispersion, adhesion, and enabling the formulation of highly tunable MXene-based inks compatible with multiple printing and patterning techniques. This universal platform supports the development of next-generation energy-storage, biosensing, and energy- harvesting devices, offering both fundamental insights and practical design guidelines for diverse technological applications.

목차 (Table of Contents)

• CHAPTER 1 INTRODUCTION AND LITERATURE REVIEW 1
• 1.1. Ti3C2Tx MXene: Structure, Properties 1
• 1.2. Applications of MXene ink in printable energy devices 5
• 1.3. Limitations of pristine MXene in printable energy devices 6
• 1.3.1. Restacking as a common issue in ultrathin 2D materials 6
• 1.3.2. Easy to be oxidized 6
• 1.3.3. Instability and poor dispersibility in organic solvents 8
• 1.3.4. Need surfactant or binder additives to be adhesive to several kind of substrate 9
• 1.4. Amphiphilic Alkoxysilane Compound and its previous applications as Dispersants and Adhesion Promoters 10
• 1.5. Motivation and Research Objectives 12
• CHAPTER 2 PREPARATION AFAO FUNCTIONALIZED-MXENE INK 15
• 2.1. Materials 15
• 2.2. Preparation multilayer MXene and colloidal MXene 15
• 2.3. Preparation of Amphiphilic Alkoxysilane oligomer (AFAO) 16
• 2.4. Characterization methods 17
• CHAPTER 3 CHARACTERISTICS AND DISPERSIBILITY OF PRISTINE MXENE AND AFAO-FUNCTIONALIZED MXENE 18
• 3.1. AFAO-MXene surrface modification mechanism 18
• 3.2. Morphology 20
• 3.3. Surface chemistry properties 22
• 3.3.1. XRD analysis 22
• 3.3.2. Raman 24
• 3.3.3. FT-IR analysis 24
• 3.3.4. TGA analysis 25
• 3.3.5. X-ray photoelectron spectroscopy (XPS) analysis 26
• 3.4. Dispersion in several kinds of solvent 29
• 3.5. Oxidation and Stability 30
• 3.6. Quick checking self-adhesion of different types of AFAO-MXene 32
• 3.7. Conclusion 34
• CHAPTER 4 FLEXIBLE AFAO-MXENE ELECTRODES FOR SYMMETRIC SUPERCAPACITOR 36
• 4.1. Introduction 36
• 4.2. Methodology 39
• 4.2.1. Preparation of AFAO-MXene ịnk 39
• 4.2.2. Fabrication of electrodes and solid-state symmetric supercapacitor 39
• 4.2.3. Electrochemical measurements 42
• 4.3. Results and discussion 43
• 4.3.1. Characteristics of AFAO-MXene and PVDF-MXene inks 43
• 4.3.2. Investigation of electrode potential window and symmetric SSC 43
• 4.3.3. Electrochemical Characterization of MXene Electrodes 44
• 4.3.3. Electrochemical Characterization and Bending test of SSCs 48
• 4.4. Conclusion 55
• CHAPTER 5 AFAO–MXENE ASYMMETRIC ULTRA-MICRO SUPERCAPACITOR FABRICATED BY ELECTROHYDRODYNAMICALLY (EHD) PRINTING 57
• 5.1 Introduction 57
• 5.2 Methodology 59
• 5.2.1. Preparation of AFAO-MXene ink for EHD printing 59
• 5.2.2. Fabrication of microelectrode 59
• 5.2.3. Electrohydrodynamic jet printing 60
• 5.2.4. Characterization 60
• 5.3 Results and discussion 61
• 5.3.1. AFAO-MXene ink properties 61
• 5.3.2. Optimization printing operation 62
• 5.3.3. Electrochemical properties 66
• 5.3.4. Integrative Electrochemical Performance of MSCs 70
• 5.4 Conclusion 71
• CHAPTER 6 APPLICATION OF AFAO- MXENE AS NANOFILLER FOR PVDF-BASED TRIBOELECTRIC LAYER OF TENG 73
• 6.1 Introduction and literature review 73
• 6.2 Methodology 76
• 6.2.1. Preparation AFAO-MXene 76
• 6.2.2. Fabrication of PVDF, PVDF/Ti3C2Tx solution for TENG electrode 77
• 6.2.3. Fabrication of TENG device 77
• 6.2.4. TENG measurement 77
• 6.3 Results and discussion 78
• 6.3.1. The electrical characterization of the TENG using different types of MXene 78
• 6.3.2. The electrical characterization of the TENG using different types of A20M-PVDF with different mixing ratios 81
• 6.4 Conclusion 85
• CHAPTER 7 GENERAL CONCLUSION AND OUTLOOK 86
• List of publication 90
• References 92