Metal chalcogenide nanostructures : materials synthesis and applications for energy/transistor devices

다국어 초록 (Multilingual Abstract)

Metal chalcogenides have attracted significant attention due to their excellent physical and chemical properties. Until now, numerous efforts have been devoted to the synthesis of metal chalcogenides and their potential applications in many research fields, such as energy storage and conversion devices, (opto)electronics, etc. However, the performances of metal chalcogenides-based devices such as electrochemical capacitance of supercapacitors (SCs), hydrogen evolution reaction (HER) activity of electrocatalysts, or mobility of thin-film transistors (TFTs) need further improvement.
Metal sulfides such as CoS, MnS, NiS, etc, have been proven excellent candidates for energy storage and conversion devices because of their good conductivity and chemical stability. Compared with single metal sulfides, bi-metal sulfides-based electrodes show the enhanced electrochemical capacitance for SCs because of the synergetic effect of bi-metal. Taking the advantages of cobalt ion, manganese ion, and nanoparticles (NPs) morphology, I synthesized manganese cobalt sulfide NPs by a hydrothermal method and explored the electrochemical performance. Otherwise, to enhance the catalytic behavior of NiS, I used a cost-effective method to synthesize NiS nanorods (NRs)/graphene (Gr) heterostructure on a three-dimensional (3D) substrate that can offer more surface active sites and improve the structural stability. As a result, the synthesized NiS NRs/Gr presented superior catalytic activity and cycling stability in both acidic and alkaline media.
Metal tellurides are considered promising candidates for energy storage and conversion systems because of their superior metallic conductivity. However, the construction of metal tellurides as a bifunctional material for SCs and HER electrocatalysts remains challenging. As reported recently, materials with hollow structures show more advantages for energy storage and conversion systems because the unique morphology can boost the carrier charge transfer. Hence, I attempted to synthesize the hollow nickel telluride (NiTe2) with a simple strategy and employed it as a bifunctional material for SCs and HER.
Nowadays, developing high-performance TFTs based on metal tellurides is a hot research topic. However, the poor electric performance of metal tellurides-based TFTs limited their commercial application. Based on the recent reports, long nanowire shows great potential in optimizing the electric property, because of the large length-to-diameter aspect ratio, high transmittance, good conductivity and excellent mechanical compliancy. Hence, I used a facile method to fabricate high-quality and uniform tellurium (Te) and metal tellurides nanowires and further investigated their electric performance for TFTs.

목차 (Table of Contents)

• Abstract 1
• Chapter 1. Introduction 3
• 1.1 Organization of dissertation 5
• 1.2 Bibliography 7
• Chapter 2. Background of Metal Chalcogenides 9
• 2.1 Fundamentals of metal chalcogenides 9
• 2.2 Fabrication methods for metal chalcogenides 12
• 2.3 Applications of metal chalcogenides 14
• 2.4 Bibliography 20
• Chapter 3. Fabrication of Manganese Cobalt Sulfide Nanoparticles asHigh-Performance Supercapacitor Electrode 26
• 3.1 Introduction 26
• 3.2 Experimental section 28
• 3.2.1 Hydrothermal synthesis of MnCoSx NPs 28
• 3.2.2 Materials characterizations 29
• 3.2.3 Electrochemical characterizations 29
• 3.2.4 Electrochemical performance calculations 30
• 3.3 Results and discussion 30
• 3.4 Conclusions 39
• 3.5 Bibliography 40
• Chapter 4. Fabrication of Nanorods-shaped Nickel Sulfide on GrapheneasAdvanced Hydrogen Evolution Electrocatalysts 43
• 4.1 Introduction 43
• 4.2 Experimental section 46
• 4.2.1 Synthesis of Gr on CC 46
• 4.2.2 Synthesis of NiS-Gr-CC electrocatalysts 47
• 4.2.3 Materials characterizations 47
• 4.2.4 Electrochemical characterizations 47
• 4.2.5 Theoretical calculations 48
• 4.3 Results and discussion 50
• 4.4 Conclusions 69
• 4.5 Bibliography 70
• Chapter 5. Fabrication of Hollow NiTe2 Nanotubes as Efficient Active Material for Hydrogen Evolution Electrocatalysts and Supercapacitors 76
• 5.1 Introduction 76
• 5.2 Experimental section 78
• 5.2.1 Fabrication of hollow NiTe2 nanotubes 79
• 5.2.2 Fabrication of NiTe2 working electrode for HER 79
• 5.2.3 Electrocatalytic HER characterizations 80
• 5.2.4 Fabrication of NiTe2 electrode for SCs and electrochemical capacitancecharacterizations 80
• 5.2.5 Electrochemical calculations 81
• 5.2.6 Materials characterizations 81
• 5.3 Results and discussion 82
• 5.4 Conclusions 95
• 5.5 Bibliography 96
• Chapter 6. Tellurium and A Series of Metal Tellurides Nanowires as ActiveMaterials in Thin Film Transistor 101
• 6.1 Introduction 101
• 6.2 Experimental section 104
• 6.2.1 Fabrication of Te nanowires 104
• 6.2.2 Fabrication of various metal tellurides nanowire 104
• 6.2.3 Materials characterizations 105
• 6.2.4 Fabrication of TFT 105
• 6.2.5 Devices characterizations 105
• 6.3 Results and discussion 106
• 6.4 Conclusions 120
• 6.5 Bibliography 121
• Chapter 7. Conclusions and Future Work 124