Study on the Photodegradation Efficiency of Ferromagnetic Fe-Added TiO2 Photocatalysts Based on the Orientation of Magnetization

다국어 초록 (Multilingual Abstract)

Study on the Photodegradation Efficiency of Ferromagnetic Fe-Added TiO2 Photocatalysts Based on the Orientation of Magnetization Kim, Jin Su Department of Fusion Science and Technology Sun Moon University A magnetized semiconductor is a material that utilizes the Hall effect by magnetizing a semiconductor. The electrons inside a magnetized semiconductor exhibit behavior similar to that of a two-dimensional material within a three-dimensional substance due to the Hall effect. In this study, we synthesized a magnetized semiconductor by doping TiO2, a three-dimensional semiconductor material, with Fe to create a ferromagnetic compound. This magnetized semiconductor was then used to investigate the effect of magnetization on photocatalytic efficiency by examining changes in photodegradation efficiency according to the direction of magnetization. In this research, we prepared -Fe2O3-impregnated TiO2 and Fe-doped TiO2, which exhibit ferromagnetic properties at room temperature. XRD, Raman shift, and SEM analyses confirmed that the Fe-doped TiO2 was synthesized as a single-phase anatase. Additionally, BET, DRS, PL, and VSM analyses were conducted to examine the structural, optical, and magnetic properties. Finally, the photocatalytic activity was evaluated based on the orientation of magnetization by analyzing the degradation of dyes, assessing both the activity and reaction rate of the photocatalyst. It was observed that Fe-doped TiO2 showed an improvement in dye degradation efficiency by up to 13.9% and an increase in reaction rate by up to 16.3%, depending on the direction of magnetization. These results suggest that the Hall effect, induced by magnetization, maximizes electron transport control, leading to improved performance. This confirmed that magnetization enables control of electron transport in photocatalyst, making it possible to transform three-dimensional materials into two-dimensional-like behavior.

국문 초록 (Abstract)

강자성체 Fe 첨가 TiO2 광촉매의 자화 방향에 따른 광분해 효율 연구 김진수 융합과학기술학과, 융합과학기술공학전공 선문대학교 일반대학원 자화반도체란 반도체를 자화시켜 홀효과를 이용하는 물질이다. 자화반도 체 내부의 전자는 홀효과에 의하여 3차원물질 내부에서 2차원물질과 같은 거 동을 가지게 된다. 이를 3차원 반도체 물질인 TiO2에 Fe를 함침/도핑시켜 강 자성체로 합성하여 착자를 진행하여 자화반도체를 제조하였다. 이를 이용하 여 광촉매에서 자화반도체의 영향을 확인하기 위하여 자화방향에 따라 광분 해효율변화를 확인하였다. 본 연구에서는 상온에서 강자성체 성질을 가지는 -Fe2O3-impregnated TiO2와 Fe-doped TiO2을 제조하였다. 이후 Fe-doped TiO2를 XRD, Raman shift와 SEM를 통하여 아나타제 단일상으로 합성된 것을 확인하였다. 그리고 BET와 DRS, PL와 VSM을 추가적으로 분석하여 구조적인 성질과 광학적 특 성, 자기적 성질을 확인하였다. 마지막으로 자화방향에 따른 광촉매활성 평가 를 염료분해를 통해 광촉매의 활성도와 반응속도에 대해 분석하였다. Fe가 도핑된 TiO2는 자화방향에 따라 염료분해 효율이 최대 13.9%까지 향상되는 것을 확인하였고, 반응속도는 최대 16.3%까지 향상되는 것을 확인 하였다. 이러한 결과는 자화를 통한 홀효과가 전자이동제어를 극대화하여 향 상된 것으로 사료된다. 이를 통해 자화가 광촉매 물질의 전자이동제어를 가 능케 하며 3차원물질의 2차원화가 가능하다는 것을 확인하였다. 주제어: 자화반도체, 3D materal, Hall Effect, 광촉매(TiO2), Fe-doped TiO2, 광촉매 활성도, 광촉매 반응속도

목차 (Table of Contents)

• CHAPTER 1. Introduction 1
• CHAPTER 2. Literature survey 3
• 2.1. Magnetized semiconductor 3
• 2.2. Two-dimensional material 6
• 2.3. The theory of ferromagnetic materials 8
• 2.3.1. Magnetic material 8
• 2.3.2. Types of Magnetic material 8
• 2.3.3. Types of Ferromagnet 10
• 2.3.4. Curie temperature, Neel temperature 12
• 2.3.5. Hysteresis loop 14
• 2.3.6. Hall Effect 16
• 2.4. Ferromagnet Fe2O3 18
• 2.5. Semiconductor 20
• 2.5.1. Energy band 20
• 2.5.2. Classification of Semiconductors 21
• 2.5.3. Direct Band Gap and Indirect Band Gap 22
• 2.6. Photocatalyst 23
• 2.6.1. Photocatalyst reaction 23
• 2.6.2. Photocatalytic activity and kinetics 25
• 2.7. Photocatalyst TiO2 27
• 2.7.1. Photocatalyst TiO2 of characteristics 27
• 2.7.2. Visible light photocatalyst TiO2 30
• 2.7.3. Fe-added TiO2 31
• Chapter 3. Result and discussion 32
• 3.1. Ferromagnetic α-Fe2O3/TiO2 Catalyst By Impregnation 32
• 3.1.1. Ferromagnetic α-Fe2O3/TiO2 Catalyst Preparation By Impregnation Method1 32
• 3.1.1.1. XRD analysis 34
• 3.1.1.2. SEM analysis 38
• 3.1.1.3. Result and discuss 39
• 3.1.2. Ferromagnetic α-Fe2O3/TiO2 Catalyst Preparation By Impregnation Method2 40
• 3.1.2.1. XRD analysis 42
• 3.1.2.2. Raman shift analysis 45
• 3.1.2.3. Evaluation of photocatalytic activity 47
• 3.1.2.4. Result and discuss 50
• 3.2.1. Ferromagnetic Fe-TiO2 Catalyst Preparation By Doping 51
• 3.2.1.1. XRD analysis 53
• 3.2.1.2. FE-SEM analysis 56
• 3.2.1.3. Raman shift analysis 58
• 3.2.1.4. Textural analysis 60
• 3.2.1.5. DRS analysis 63
• 3.2.1.6. PL analysis 67
• 3.2.1.7. VSM analysis 68
• 3.2.1.8. Evaluation of photocatalytic activity and kinetics 71
• 3.2.1.9. Result and discuss 82
• CHAPTER 4. Conclusion 84
• CHAPTER 5. Reference 86