Title Page
Contents
ABSTRACT 10
Ⅰ. Introduction 12
1.1. The Research Background of Water Splitting and Seawater Splitting 12
1.2. The Electrochemical Methods for Evaluating the Performance of Water Splitting 17
1.2.1. Linear Sweep Voltammetry 17
1.2.2. Tafel slope 18
Ⅱ. Materials and Experimental Method 20
2.1. Materials 20
2.2. Experimental Method 20
2.2.1. Synthesis of CoFe LDH on Nickel foam 20
2.2.2. Synthesis of CoFe LDH@ZI 21
2.2.3. Synthesis of CoFe LDH@PNC 21
2.3. Characterization 22
2.3.1. Materials Characterization 22
2.3.2. Electrochemical Characterization 23
Ⅲ. Result and Discussion 24
3.1. Material Characterization 24
3.2. Electrochemical Characterization 44
3.2.1. Water Splitting 44
3.2.2. Direct Seawater Splitting 56
Ⅳ. Conclusion 66
References 67
Appendix 73
Abstract (in Korean) 74
Figure 1-1. Pourbaix diagram for artificial seawater model. 14
Figure 3-1. Schematic illustration of fabrication procedure of CoFe LDH@PNC. 25
Figure 3-2. Real images of CoFe LDH, CoFe LDH@ZIF, CoFe LDH@PNC. 27
Figure 3-3. SEM images of (a),(d) CoFe LDH, (b), (e) CoFe LDH@ZIF, and (c),(f) CoFe LDH@PNC. 28
Figure 3-4. elemental mapping images of (a) CoFe LDH, and (b) CoFe LDH@ZIF. 29
Figure 3-5. SEM, and elemental mapping images of CoFe LDH@PNC at cross section. 30
Figure 3-6. SEM images of CoFe LDH@ZIF-x hr; (a) 0 hr, (b) 0.5 hr, (c) 1 hr, (d) 3 hr, and (e) 6 hr. 32
Figure 3-7. SEM images of CoFe LDH@PNC-x hr; (a) 0 hr, (b) 0.5 hr, (c) 1 hr, (d) 3 hr, and (e) 6 hr. 34
Figure 3-8. (a)-(c) TEM images, (d) EDS elemental mapping images of CoFe LDH@PNC. 36
Figure 3-9. TEM images of CoFe LDH@P. 37
Figure 3-10. XRD spectra of CoFe LDH, CoFe LDH@ZIF, CoFe LDH@P, and CoFe LDH@PNC. 38
Figure 3-11. N₂ adsorption-desorption isotherm of CoFe LDH@P, and CoFe LDH@PNC (inset: pore size distribution plot with NL-DFT method). 40
Figure 3-12. XPS spectra of CoFe LDH@P and CoFe LDH@PNC (a) survey, (b) Co 2p, (c) Fe 2p, (d) O 1s, (e) P 2p, (f) N 1s, and (g) C 1s. 43
Figure 3-13. Electrochemical properties for OER. (a) LSV curves, (b) Comparison of the overpotentials required to reach current densities of 10, 100, 500, and 1000 mA cm⁻... 45
Figure 3-14. Electrochemical properties for OER. (a) LSV curves, (b) Comparison of the overpotentials required to reach current densities of 10, 100, 500, and 1000 mA cm⁻... 47
Figure 3-15. Electrochemical properties for HER. (a) LSV curves, (b) Comparison of the overpotentials required to reach current densities of 10, 100, 500, and 1000 mA cm⁻... 49
Figure 3-16. Electrochemical properties for HER. (a) LSV curves, (b) Comparison of the overpotentials required to reach current densities of 10, 100, 500, and 1000 mA cm⁻... 51
Figure 3-17. (a) Cdl curves, CV curves of (b) CoFe LDH@PNC-0.5 hr, (c) CoFe LDH@PNC-1 hr, (d) CoFe LDH@PNC-3 hr, and (e) CoFe LDH@PNC-6 hr at...[이미지참조] 53
Figure 3-18. (a) Cdl curves, CV curves of (b) CoFe LDH@PNC-0.5 hr, (c) CoFe LDH@PNC-1 hr, (d) CoFe LDH@PNC-3 hr, and (e) CoFe LDH@PNC-6 hr at...[이미지참조] 55
Figure 3-19. Collection of seawater. (a) Photograph of Oido Island, Siheung, Republic of Korea, (b) collected seawater. 58
Figure 3-20. The real images of 1M KOH, 1M KOH + 0.5M NaCl, and 1M KOH + seawater electrolyte. 59
Figure 3-21. Electrochemical parameters of CoFe LDH@PNC for direct seawater splitting in 1M KOH, 1M KOH + 0.5M NaCl, and 1M KOH + seawater. LSV curves... 60
Figure 3-22. (a) Schematic illustration of full-cell for overall water-splitting at elevated temperature by sun, and (b) LSV curves of overall water-splitting in 1M KOH, 1M... 61
Figure 3-23. (a) OER, and (b) HER LSV curves of CoFe LDH@PNC in 1 M KOH, 1M KOH+0.5M NaCl, and 1M KOH + seawater with or without 10 mM KSCN. 63
Figure 3-24. Chronopotentiometry at 100 mA cm⁻² of CoFe LDH@P and CoFe LDH@PNC for (a) OER, and (b) HER (inset: Phosphorus concentration in the... 65