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Title Page

ABSTRACT

국문요약

Contents

Introduction 20

Experimental Section 30

Reference 46

Part 1: Synthesis and Electrocatalytic performance of electrode material in Fuel Cell 50

CHAPTER-1. Novel ordered nanoporous graphitic carbon nitride with C₃N₄ stoichiometry as a support for Pt-Ru anode catalyst in DMFC 51

1.1. Introduction 51

1.2. Results and Discussion 53

1.3. Conclusion 62

1.4. References 63

CHAPTER-2. A highly efficient synthesis approach of supported Pt-Ru catalyst for direct methanol fuel cell 67

2.1. Introduction 67

2.2. Results and Discussion 69

2.3. Conclusion 90

2.4. References 90

CHAPTER-3. Effect of pH on electrocatalytic property of supported PtRu catalysts in proton exchange membrane fuel cell 97

3.1. Introduction 97

3.2. Results and Discussion 100

3.3. Conclusion 110

3.4. References 111

Part 2: Li Storage Performance of Various Nanostructured Porous Carbons as Anode Material 115

CHAPTER-4. Ordered multimodal porous carbon with hierarchical nanostructure for high Li storage capacity and good cycling performance 116

4.1. Introduction 116

4.2. Results and Discussion 119

4.2.1. Surface and structural characteristics of OMPC 119

4.2.2. Li storage in various porous carbon materials 123

4.3. Conclusion 130

4.4. References 131

CHAPTER-5. Ultra-high Li storage capacity achieved by hollow carbon capsules with hierarchical nanoarchitecture 136

5.1. Introduction 136

5.2. Results and Discussion 137

5.2.1. Surface and structural characteristics of HCMSC 137

5.2.2. Li storage in various porous carbon materials 141

5.3. Conclusion 149

5.4. References 150

CHAPTER-6. Morphology dependent Li storage performance of ordered mesoporous carbon as anode material 155

6.1. Introduction 155

6.2. Results and Discussion 159

6.3. Conclusion 170

6.4. References 171

Conclusion 176

Publications 181

List of Tables

Table 1.1. Structural and conductivity parameters of porous supports prepared in present work 62

Table 2.1. Electrocatalytic activity towards methanol oxidation of Pt-Ru/VC catalysts prepared by NaBH₄ reduction or by HD-H₂ strategy alone with that from commercial E-TEK catalyst. 85

Table 3.1. Particle size and fuel cell performance for the Pt-Ru (40 wt%)/VC catalysts prepared by the HD-H₂ under various pH values or by NaBH₄ method 110

Table 4.1. Structural parameters for the CMK-3 and OMPC. 122

Table 5.1. Kinetic parameters derived from the Nyquist plots for the CMK-3 and HCMSC. 148

Table 6.1. Structural properties of OMC carbons synthesized with various SBA- 15 templates. 162

Table 6.2. Kinetic parameters derived from the Nyquist plot for the various OMCs. 169

List of Figures

Figure 1.1. SEM image of resulting carbon nitride framework (a) and XRD patterns for the carbon nitride and ordered macroporous carbon (b). 53

Figure 1.2. XPS spectra of the carbon nitride. 54

Figure 1.3. Atomic structure of a graphitic-C₃N₄ single layer. Nitrogen atoms occupy two different types of positions in the layer, labeled α and β in the figure. 55

Figure 1.4. FT-IR spectrum of the carbon nitride. 56

Figure 1.5. Nitrogen adsorption-desorption isotherms at -196 ℃ for the graphitic carbon nitride. 57

Figure 1.6. TEM image (a) and high resolution TEM images (b and c) of Pt-Ru/C₃N₄ catalyst. 59

Figure 1.7. The polarization and power density curves for direct methanol fuel cell using Pt-Ru/C₃N₄ or commercial E-TEK catalyst as an anode determined at 30 ℃ and 60 ℃. 60

Figure 1.8. The polarization and power density curves for direct methanol fuel cell using Pt-Ru/C₃N₄, Pt-Ru/OMC or a commercial Pt-RU/E-TEK catalyst as an anode determined at 60 ℃. 60

Figure 1.9. The polarization and power density curves for direct methanol fuel cell using Pt-Ru/C₃N₄ or a commercial Pt-Ru/E-TEK catalyst as an anode determined at 30 ℃ and 60 ℃. 61

Figure 2.1. Representative HRSEM and HRTEM images for the various molar ratio (urea/Pt-Ru) of Pt-Ru(60 wt%)/VC catalysts (HD-H₂), (a, b) 10, (c, d) 50 and (e, f) 100 times 70

Figure 2.2. Representative HRSEM images for the various Pt-Ru/VC catalysts, (a) Pt-Ru (60 wt%)/VC (HD-H₂), (b) Pt-Ru (60 wt%)/VC (NaBH₄) and (c) Pt-Ru (60 wt%)/VC (E-TEK). 72

Figure 2.3. HRTEM images (a) Pt-Ru (60 wt%)/VC (HD-H₂), (b) Pt-Ru (60 wt%)/VC (NaBH₄), and (c) Pt-Ru particle size distribution diagram for the Pt-Ru (60 wt%)/VC (HD-H₂) 73

Figure 2.4. Histograms derived from the HRTEM images of various Pt-Ru(60 wt%)/VC catalysts, (a) prepared by NaBH₄ reduction and (b) Commercial E-TEK one. 74

Figure 2.5. Typical HRTEM image for the Pt-Ru(60 wt%)/VC catalyst prepared by pH control through external addition of NaOH followed by H₂ reduction at 300 ℃. 75

Figure 2.6. (a) XPS spectra with wide scan and (b) Nls for the VC supported Pt-Ru complex species collected in a solution in the presence of urea or NaOH.... 76

Figure 2.7. XRD patterns for the various Pt-Ru/VC catalysts. The inset shows plots for the 220 reflections obtained with a slow scan rate of 1˚/2 min. 78

Figure 2.8. Thermogravimetric analysis curves for the various Pt-Ru (60 wt%)/VC catalysts. 80

Figure 2.9. CO stripping voltammograms for the various Pt-Ru/VC catalysts in 0.5 M H₂SO₄ at room temperature with a scan rate 25 mV/s, (a) Pt-Ru (60 wt%)/VC (HD-H₂), (b) Pt-Ru (60 wt%)/VC (NaBH₄) and (c) Pt-... 84

Figure 2.10. Typical cyclic voltammograms obtained in 1.0 M CH₃OH -0.5 M H₂SO₄ for supported 60 wt% Pt-Ru catalysts prepared by different methods. 86

Figure 2.11. Representative chronoamperograms obtained at 0.4 V (vs Ag/AgCl) in 1.0 M CH₃OH - 0.5 M H₂SO₄ for the Pt-Ru catalysts prepared by different methods. 87

Figure 2.12. Cell polarization and power density plots for the various Pt-Ru (60 wt%)/VC catalysts at 60 ℃ (a) with O₂-fed cathode mode and (b) with air-fed cathode mode 89

Figure 3.1. HR-SEM and HR-TEM images of 40 wt% PtRu/VC catalysts (inset: high magnification TEM images). 101

Figure 3.2. HR-SEM and HR-TEM images of Pt-Ru/VC catalysts (HD-H₂) 102

Figure 3.3. Thermogravimetric analysis curves for the various Pt-Ru/VC Ux catalysts prepared using HD-H₂ method. 103

Figure 3.4. The XRD patterns of 40 wt% Pt-Ru/VC catalysts synthesized using HD-H₂ at various pH values and Pt-Ru/VC-NaBH₄ catalyst. 104

Figure 3.5. CO stripping voltammograms for the various Pt-Ru (40 wt%)/VC catalysts ((a) NaBH₄, (b) U1 (pH 3~4), (c) U2 (pH 5~6), (d) U3 (pH 7~8) and (e) U4 (pH 9~10)) in 0.5 M H₂SO₄ at 25 mVs-1(이미지참조) 107

Figure 3.6. (a) The polarization and power curves for PEMFC using 40 wt% Pt-Ru/VC catalysts as anode and a commercial E-TEK Pt (20 wt%)/VC catalyst as cathode.... 109

Figure 4.1. Typical SEM and TEM images for OMPC. 120

Figure 4.2. Typical nitrogen adsorption-desorption isotherms at 77 K and the derived PSD for OMPC. 121

Figure 4.3. Micropore size distribution curve of OMPC obtained by using the Horvath-Kawazoe method. 122

Figure 4.4. Representative TEM images for CMK-3. 123

Figure 4.5. Typical nitrogen adsorption-desorption isotherms at -196 ℃ and the derived PSD for CMK-3. 124

Figure 4.6. CV plots during the first 5 cycles for OMPC in 1M LiClO₄-EC-DEC, scan ate: 0.1 ㎷ s-1.(이미지참조) 125

Figure 4.7. Galvanostatic charge/discharge curves at 100 ㎃ g-1 for OMPC (a) and the specific capacities derived from the delithiation process shown against the cycle number for OMPC and CMK-3 (b).(이미지참조) 126

Figure 4.8. Specific capacities obtained at various rates for OMPC and CMK-3. 128

Figure 4.9. Typical Nyquist plots observed at various electrode materials. 129

Figure 5.1. Typical SEM (a), and TEM (b) images of HCMSC capsules. 138

Figure 5.2. Thermogravimetric analysis curves for the HCMSC. 139

Figure 5.3. The Nitrogen adsorption-desorption isotherms at 77K and derived PSD for HCMSC capsules (inset). 140

Figure 5.4. Representative SEM (a) and UHR-SEM (b) images for CMK-3. 140

Figure 5.5. Typical nitrogen adsorption-desorption isotherms at -196 ℃ and the derived PSD for CMK-3. 141

Figure 5.6. CV plots during the first 6 cycles for HCMSC capsules in 1.0 M LiPF6(이미지참조) 142

Figure 5.7. Galvanostatic charge/discharge curves at 100 ㎃ g-1 for HCMSC capsules.(이미지참조) 143

Figure 5.8. Galvanostic charge/discharge curves at 100 mAh g-1 for commercial graphite, CMK-3, and HCMSC capsules (the 2nd cycle).(이미지참조) 144

Figure 5.9. Cycling performance and coulombic efficiency of commercial graphite, CMK-3, and HCMSC capsules at a specific current of 100 mA g-1.(이미지참조) 145

Figure 5.10. Rate performances of commercial graphite, CMK-3 and HCMSC capsules at different current densities from 100 to 1000㎃ g-1 and then back to 100 ㎃ g-1.(이미지참조) 146

Figure 5.11. Typical Nyquist plots observed at various electrode materials. 147

Figure 6.1. Typical SEM and TEM images of OMC-1(a, b), OMC-2(c, d) and OMC-3(e, f). 160

Figure 6.2. Small-angle XRD patterns of OMCs (a) and the N₂ adsorption-desorption isotherms at 77 K for (■) OMC-1, (▲) OMC-2 and (●) OMC-3 (b). 162

Figure 6.3. Galvanostatic charge/discharge curves at 100 ㎃ g-1 for OMC-1(a), OMC-2(b) and OMC-3(c).(이미지참조) 163

Figure 6.4. Galvanostatic charge/discharge curves at 100 mAh g-1 for commercial graphite and various OMCs for the 2nd cycle.(이미지참조) 165

Figure 6.5. Cycling performance and coulombic efficiency of commercial graphite and various OMCs at a specific current of 100 ㎃ g-1.(이미지참조) 166

Figure 6.6. Rate performances of commercial graphite and OMCs at different current densities from 100 to 1000㎃ g-1 and then back to 100 ㎃ g-1.(이미지참조) 168

Figure 6.7. Typical Nyquist plots recorded at various OMC electrode materials. 169

List of Schemes

Scheme 1. A typical scheme for synthesis of OMPC. 36

Scheme 2. A typical scheme for the synthesis of rod-shaped OMC. 39

초록보기

 최근 10 년간 화석연료들(석탄, 석유등)의 자원 매장량 한계 및 환경파괴등과 같은 많은 환경문제들로 인해 친환경 에너지원 및 에너지저장에 관련된 연구가 폭넓게 이루어져왔다. 이러한 다양한 친환경에너지원 및 저장체들 중에서 연료전지 및 리튬이차전지는 높은 에너지밀도, 내구성등의 장점들로 인해 대부분 성공적으로 상용화되었다.

이 논문은 친환경에너지 생산뿐아니라 저장을 위한 몇몇 새로운 흥미있는 물질들에 관한 연구를 목적으로 한다. 이 논문은 크게 두개의 파트로 나누었다. 파트 I 은 새로운 나노구조화된 고전도성 탄소 질화물을 담지체로 이용한 Pt-Ru 촉매의 합성뿐만 아니라 높은 균일도와 분산도를 가지는 두 가지의 새로운 친환경 촉매합성법에 관한 연구로 이루어져있다. 결과적으로 나노구조체들에서의 합성조건들의 영향, 또한 연구하고, 분석하였다. 이렇게 합성된 물질들은 직접 메탄올 연료전지, 고분자 전해질막 연료전지의 산화전극 촉매로써의 응용성을 타진하였으며, 상용물질들이나 다른 방법들로 합성된 탄소물질들과 비교 연구하였다.

반면, 파트 II 에서는 흥미있는 다양한 형태나 균일한 메조 다공성 구조를 같는 높은 표면적과 같은 뛰어난 표면성질의 나노구조화된 탄소 물질들의 합성 및 특성평가로 이루어져있다. 이러한 물질들은 리튬이차전지의 음극물질로써의 응용성과 표면성질과 성능과의 상호관계에 관하여 연구하였다.