표제지
국문초록
목차
I. 서론 17
II. 이론적 고찰 19
1. 자성나노입자 19
2. 이산화티탄 21
3. 광촉매반응 23
3.1. 광촉매반응의 원리 23
3.2. 자성나노입자, 귀금속을 활용한 광촉매 25
4. 리튬이온이차전지 27
4.1. 전지의 개요 27
4.2. 리튬이온이차전지 29
III. 실험장치 및 방법 31
1. 실험기기 및 시약 31
2. 실험 조건 및 방법 33
2.1. 자성 나노 입자의 제조 33
2.2. 자성 나노 입자의 안정화 34
2.2.1. APTMS coating 34
2.2.2. Diamine coating 34
2.3. 자성 - 이산화티탄 나노복합체 제조 35
2.4. 광촉매 실험 37
2.4.1. 금속이 도핑된 자성 - 이산화티탄 나노복합체 제조 37
2.4.2. 유기용매 분해효율 측정 39
2.5. 리튬이온이차전지 실험 41
2.5.1. Half-cell 제조 41
2.5.2. 전지성능측정 41
3. 분석 43
3.1. TEM 43
3.2. SEM 43
3.3. FT-IR 43
3.4. XRD 43
3.5. PSA 44
3.6. VSM 44
3.7. PL spectroscopy 44
3.8. UV-vis spectroscopy 44
3.9. 전기화학적 분석 45
IV. 결과 및 고찰 46
1. 자성나노입자의 제조 46
2. 자성나노입자의 기능화 49
2.1. APTMS coating 49
2.1.1. 온도와 pH에 따른 size 분포 51
2.1.2. APTMS 코팅에 따른 자성분석 53
2.2. Diamine coating 55
2.2.1. 주입량 및 탄소 사슬 수 에 따른 size 분포 56
2.2.2. 용액의 성분에 따른 size 분포 60
2.2.3. Diamine 코팅에 따른 자성분석 63
3. 자성 - 이산화티탄 나노복합체의 제조 65
3.1. 자성 - 이산화티탄 나노복합체의 결합 65
3.2. 자성 - 이산화티탄 나노복합체의 성분분석 68
3.3. 자성 - 이산화티탄 나노복합체의 격자구조 71
3.4. 자성 - 이산화티탄 나노복합체의 자성분석 74
4. 응용 I - 광촉매로의 활용 76
4.1. 금속이 도핑된 자성 - 이산화티탄 나노복합체의 제조 76
4.2. 금속이 도핑된 자성 - 이산화티탄 나노복합체의 광학적 특성 78
4.3. 광촉매로서의 유기용매 분해효율 측정 82
4.3.1. 은이 도핑된 자성 - 이산화티탄 나노복합체 82
4.3.2. 금이 도핑된 자성 - 이산화티탄 나노복합체 84
4.3.3. 재사용한 은(또는 금)이 도핑된 자성 - 이산화티탄 나노복합체 88
5. 응용 II - 리튬이온이차전지로의 활용 91
5.1. Cyclic voltammetry 91
5.2. Cycle에 따른 용량 특성 분석 97
5.3. 충·방전 특성 분석 102
V. 결론 105
VI. 참고문헌 107
ABSTRACT 110
Table 1. Physical properties of TiO₂. 22
Table 2. Characteristics and properties of various secondary battery. 29
Table 3. Physical and chemical properties of reagents used in the synthesis of magnetic nanocomposites. 31
Table 4. The size of citrate-stabilized magnetites formed by various citrate injection times. 47
Table 5. The size of APTMS-coated magnetites by various reaction temperature. 52
Table 6. The size of APTMS-coated magnetites by various pH condition. 52
Table 7. The size of titania-encapsulated magnetite complex by various injection TEOT amounts. 66
Fig. 1. Application of magnetic nanoparticles. 20
Fig. 2. Crystal structure of TiO₂ 22
Fig. 3. Principle of photodegradation with photocatalysis. 24
Fig. 4. Principle of photodegradation with Fe₃O₄, noble metal combinated photocatalysis. 25
Fig. 5. The formation of radicals and the reaction mechanisms by photocatalyst. 26
Fig. 6. Schematic diagram of components of battery. 28
Fig. 7. Construction of lithium-ion battery. 30
Fig. 8. Schematic diagram for the fabrication of titania - encapsulated magnetite nanocomposites using sol-gel process. 36
Fig. 9. Schematic diagram for the fabrication of metal - coated Fe₃O₄@TiO₂ nanocomposites using ultrasonic reduction process. 38
Fig. 10. Experimental : Photocatalysis activity. 40
Fig. 11. Schematic diagram for the packaging process for half-cell lithium-ion battery. 42
Fig. 12. Schematic diagram for the fabrication of citrate-stabilized magnetites. 47
Fig. 13. Images of (a) TEM, and (b) SEM about citrate-stabilized magnetites. 48
Fig. 14. Schematic diagram for the fabrication of APTMS-coated magnetites. 49
Fig. 15. Images of (a) TEM, and (b) SEM about APTMS-coated magnetites. 50
Fig. 16. Magnetization curve of magnetites 54
Fig. 17. Schematic diagram for the fabrication of diamine-coated magnetites. 55
Fig. 18. Size histograms of magnetite clusters prepared by the increasing dosages of diamines with different chain lengths. 57
Fig. 19. SEM images of diamine-linked magnetite at different chain length of diamine 58
Fig. 20. FT-IR spectra of diamine-linked magnetite (D-Fe₃O₄). 59
Fig. 21. Size variation of diamine-linked magnetite clusters prepared by different solvent vol.% of water/ethanol mixture. 61
Fig. 22. SEM images of diamine-linked magnetite clusters at different solvent vol.% water / ethanol mixture 62
Fig. 23. Magnetization curve of magnetites 64
Fig. 24. Schematic diagram for the fabrication of TiO₂-encapsulated magnetite complex. 66
Fig. 25. SEM and TEM Images of titania-encapsulated magnetites with the increase of TEOT amounts 67
Fig. 26. FT-IR spectrum of : (a) C-Fe₃O₄, (b) A-Fe₃O₄, (c) A-Fe₃O₄@TiO₂. 69
Fig. 27. TEM-EDX mapping of A-Fe₃O₄@TiO₂. 70
Fig. 28. SAED images of (a) A-Fe₃O₄, (b) A-Fe₃O₄@TiO₂. 70
Fig. 29. HRTEM image of A-Fe₃O₄@TiO₂ (uncalcinated). 72
Fig. 30. XRD patterns of magnetites 73
Fig. 31. Magnetization curve of magnetites 75
Fig. 32. Magnetic separation of TiO₂ - encapsulated magnetite complex in the presence of external magnetic field. 75
Fig. 33. TEM image of Au - titanium dioxide encapsulated magnetite complexs(Fe₃O₄@TiO₂@Au). 77
Fig. 34. The photoluminescence (PL) spectra of Ag - titanium dioxide encapsulated magnetite complexs (Fe₃O₄@TiO₂@Ag) prepared by the various injection volume of 1 wt% Ag precursor 79
Fig. 35. The photoluminescence (PL) spectra of Au - titanium dioxide encapsulated magnetite complexs (Fe₃O₄@TiO₂@Au) prepared by the various injection volume of 1 wt% Au precursor 80
Fig. 36. The photoluminescence (PL) spectra of noble metal (Ag, Au) - deposited Fe₃O₄@TiO₂ nanocomposites 81
Fig. 37. Photodegradation of organics solution (methylene blue) with under UV light irradiation over Fe₃O₄@TiO₂@Ag prepared by different injection volumes of 1 wt% Ag precursor. 83
Fig. 38. Photodegradation of organics solution (methylene blue) with under UV light irradiation over Fe₃O₄@TiO₂@Au prepared by different injection volumes of 1 wt% Au precursor. 85
Fig. 39. Photodegradation of organics solution (methyl orange) with various Au-deposited TiO₂ under UV light irradiation for 30min. 86
Fig. 40. Photodegradation of organics (methylene blue) with Fe₃O₄@TiO₂, Fe₃O₄@TiO₂@Ag and Fe₃O₄@TiO₂@Au nanoparticles under UV light irradiation for 2 hours. 87
Fig. 41. The photocatalytic activity of Fe₃O₄@TiO₂@Ag(1.0mL) of recycle times under UV light irradiation at different times 89
Fig. 42. The photocatalytic activity of Fe₃O₄@TiO₂@Au(0.25mL) of recycle times under the UV light irradiation at different times 90
Fig. 43. Cyclic voltammetry curves of magnetites measured between 0 and 2.5 V 93
Fig. 44. Cyclic voltammetry curves of magnetites measured between 0 and 2.5 V at the scan rate of 0.2 ㎷/s 95
Fig. 45. The relationship of the peak current (ip) and the square root of scan rate (v1/2)(이미지참조) 96
Fig. 46. Cyclic performances of core-shell Fe₃O₄@TiO₂ nanocomplexs 98
Fig. 47. Cyclic performances of core-shell Fe₃O₄@TiO₂ at scan rate of : (a) 0.25 C, (b) 1.00 C. 100
Fig. 48. Cyclic performances core-shell Fe₃O₄@TiO₂ nanocomplexs by the increasing scan rate of : (a) Fe₃O₄@TiO₂(114 ± 32 ㎚), (b) Fe₃O₄@TiO₂(124 ± 36 ㎚). 101
Fig. 49. Charge-discharge curves of core-shell Fe₃O₄@TiO₂ nanocomplexs 104