Title Page
Contents
ABSTRACT IN KOREAN 10
PART Ⅰ. General Introduction 12
Ⅰ. Photocatalyst 12
Ⅱ. Structure, properties of Co@ZnO NPs 16
Ⅲ. Structure, properties of ZnCdS (ZnₓCd₁₋ₓS) 18
Ⅳ. Structure, properties of HMF 21
PART Ⅱ. Ion Co (Co²⁺ or Co³⁺) - doped into ZnO NPs 22
Ⅰ. Synthesis of a Co-doped ZnO NPs 22
Ⅱ. Characterizations and Photocatalytic activity test 22
2.1. Characterizations Structural 22
2.2. Photocatalytic activity test 23
Ⅲ. Result and Discussion 24
3.1. Characterizations of Co-doped ZnO NPs at the atomic scale 24
3.2. Electronic properties of Co-doped ZnO NPs 27
3.3. Photocatalytic Degradation and Selective oxidation of HMF 31
PART Ⅲ. ZnCdS (ZnₓCd₁₋ₓS) 35
Ⅰ. Synthesis of a series of ZnₓCd₁₋ₓS nanoparticles 35
Ⅱ. Characterizations and Photocatalytic activity test 36
2.1. Characterizations Structural 36
2.2. Photocatalytic Activity Test 36
Ⅲ. Result and discussion 37
3.1. Characterizations of ZnₓCd₁₋ₓS at the atomic scale 37
3.2. Structural characterizations 40
3.3. Photocatalytic degradation of ZnₓCd₁₋ₓS NPs 44
3.4. Selective Oxidation using ZnₓCd₁₋ₓS NPs 46
3.5. Wavelenght-dependent in-situ XPS measurement under irradiation 50
PART Ⅳ. Conclusion 53
PART Ⅴ. References 54
Publications 64
Poster Award 65
ABSTRACT IN ENGLISH 66
Table 1. The pristine ZnO, Co³⁺@ZnO, and Co²⁺@ZnO NPs structural parameters from EXAFS fit. 31
Table 2. Summarizes the changes in distance in the three crystallographic directions in the (100) plane of ZnS 38
Table 3. The binding energies of 2p₃/₂, Cd 3d₅/₂ and S 2p₃/₂ peaks for non-irradiated ZnₓCd₁₋ₓS NPs[이미지참조] 43
Table 4. C/C₀ for HMF after 24 hours of photocatalytic degradation using ZnxCd₁-x NPs was determined and recorded based on the wavelength used for irradiation. 46
Table 5. Summarizes the concentrations of FDCA obtained based on irradiation wavelength for PCD 25 mM HMF (starting material) using ZnₓCd₁₋ₓS NPs. 48
Figure 1. Photocatalyst reaction. 13
Figure 2. Different forms of ZnO, (a) hexagonal wurtzit and (b) cubic zinc blende 17
Figure 3. Different forms of CdS, (a) hexagonal wurtzite and (b) cubic zinc blende 19
Figure 4. Different forms of ZnS, (a) zinc blende, and hexagonal wurtzite 20
Figure 5. Mechanistic pathway for HMF oxidation 21
Figure 6. HAADF-STEM figures of (a) ZnO, (b) Co³⁺ @ZnO, and (c) Co²⁺@ZnO NPs and(d) Line profile analysis was performed to compare the composition of... 24
Figure 7. Elemental mapping of Co, O, and Zn in Co@ZnO NPs 26
Figure 8. (a) XRD patterns, (b) UV-VIS DRS spectra, (c) XPS spectra (Zn 2p and O 1s core-level spectra), and (d) EPR spectra (black: ZnO, pink: Co³⁺@ZnO,... 27
Figure 9. XAS spectra (a) Zn L-edge, (b) O K-edge, and (c) Co L-edge. (d) XANES spectra and (e) EXAFS spectra of ZnO (black line), Co³⁺@ZnO (pink line),... 29
Figure 10. PCD characteristics of (a) HMF among three ZnO NPs: ZnO NPs, Co³⁺ @ZnO NPs, and Co²⁺@ZnO NPs. Product analysis using LC-MS spectra: (b)... 31
Figure 11. Illustrates a hypothesized mechanistic HMF oxidation pathway 33
Figure 12. Three tested ZnO NPs were used in repeated cycles of HMF degradation under 365 nm illumination, with the catalysts being retrieved after... 34
Figure 13. HRTEM figures of (a) CdS, (b) Zn₀.₃Cd₀.₇S, (c) Zn₀.₅Cd₀.₅S, and (d) Zn₀.₇Cd₀.₃S NPs and (e) Line profile analysis was performed to compare the... 37
Figure 14. Elemental mapping of Cd, S, and Zn in ZnₓCd₁₋ₓS NPs with varying ion Zn²⁺ concentrations. 39
Figure 15. (a) X-ray diffraction patterns, (b) UV-VIS DRS spectra (black: CdS, green: Zn₀.₃Cd₀.₇S, pink: Zn₀.₅Cd₀.₅S, and blue: Zn₀.₇Cd₀.₃S NPs) 40
Figure 16. High-resolution XPS spectra of ZnₓCd₁₋ₓS NPs in the absence of irradiation (black: CdS, green: Zn₀.₃Cd₀.₇S, pink: Zn₀.₅Cd₀.₅S, and blue: Zn₀.₇Cd₀.₃S... 42
Figure 17. The photocatalytic degradation of HMF was studied using ZnₓCd₁₋ₓS NPs with varying ion Zn²⁺ concentrations depending on (a) 365, (b) 405, and (c)... 44
Figure 18. Concentration summary found for the oxidation of HMF with (a and c) CdS NPs, (d and f) Zn₀.₃Cd₀.₇S NPs, (g and i) Zn₀.₅Cd₀.₅S NPs, and (j and l)... 47
Figure 19. A cyclic test for the photocatalytic degradation of HMF using ZnₓCd₁₋ₓS NPs was performed 49
Figure 20. Wavelength-dependent in-situ X-ray photoelectron spectra of (a)-(i) CdS, (b)-(j) Zn₀.₃Cd₀.₇S NPs, (c)-(k) Zn₀.₅Cd₀.₅S NPs, and (d)-(l) Zn₀.₇Cd₀.₃S NPs... 50
Figure 21. Mechanistic HMF oxidation pathway 52