Title Page
Contents
ABSTRACT 12
초록 14
I. INTRODUCTION 16
II. THEORETICAL BACKGROUND 20
II-1. CO₂ electrochemical reduction reaction (CO₂ER) 20
II-1-1. Components of conventional CO₂ electrochemical reduction reaction system 20
II-1-2. Principle of electrochemical CO₂ reduction reaction 23
II-2. Research background 25
II-2-1. Materials for CO₂ electrochemical reduction 25
II-2-2. Selective CO₂ER to CO and practical applications 27
II-2-3. Various nanostructures of Zn based materials 29
II-2-4. Gas chromatography for gas phase product analysis 29
III. RESEARCH SCOPE AND PURPOSE 31
IV. EXPERIMENTAL DETAILS 33
IV-1. Synthesis of cathode electrode 33
IV-1-1. Zinc foil pretreatment 33
IV-1-2. Hydrothermal synthesis 33
IV-1-3. Electrode preparation 36
IV-1-4. H - type cell assembly and composition 38
IV-2. Microstructure and component analysis method 40
IV-2-1. X-ray Diffraction (XRD) 40
IV-2-2. Scanning electron microscope (SEM) 41
IV-2-3. Transmission electron microscope (TEM) 41
IV-2-4. X-ray Photoelectron spectroscopy (XPS) 42
IV-3. Electrochemical characterization 42
IV-4. Gas product analysis 43
V. RESULTS AND DISCUSSION 45
V-1. Microstructure and component analysis 45
V-1-1. XRD analysis 45
V-1-2. SEM and TEM analysis 47
V-1-3. XPS analysis 53
V-2. Electrochemical characterization 55
V-2-1. Electrochemical CO₂ conversion behavior 55
V-2-2. Electrochemical CO₂ conversion behavior 60
VI. CONCLUSIONS 65
VII. REFERENCE 66
Table. 1. Electrochemical potentials of possible CO₂ reduction reactions in aqueous solutions for the production of different hydrocarbon fuels 28
Table. 2. Equivalent-circuit parameters of Rs and Rct for the Zn foil, TU-ZnS, and TA-ZnS electrodes.[이미지참조] 59
Fig. 1. Components of electrochemical CO₂ reduction reaction system 24
Fig. 2. Classification of major metal catalysts for electro-reduction of CO₂ 26
Fig. 3. Electrochemical CO₂ reduction reaction pathways and intermediates 32
Fig. 4. Schematic description of hydrothermal synthesis process 35
Fig. 5. The used equipment for hydrothermal synthesis process 35
Fig. 6. Pictures of prepared working electrode after epoxy coating 37
Fig. 7. Schematic of H-type cell assembly and experimental setup 39
Fig. 8. XRD patterns and JCPDS No. of the Zn-based electrodes 46
Fig. 9. FE-SEM results of (a) TU-ZnS and (b) TA-ZnS 49
Fig. 10. Cross-section SEM images of (a) TU-ZnS and (b) TA-ZnS 50
Fig. 11. TEM results of TU-ZnS ; (a) TEM and (b) HR-TEM image, (c) EDX mapping 51
Fig. 12. TEM results of TA-ZnS ; (a) TEM and (b) HR-TEM image, (c) EDX mapping 52
Fig. 13. XPS spectra of (a) Zn 2p and (b) S 2p of TU-ZnS and TA-ZnS 54
Fig. 14. Electrochemical measurement results of Zn foil, TU-ZnS and TA-ZnS. All electrochemical measurement was performed in CO₂-saturated... 58
Fig. 15. CO₂ conversion behavior of TA-ZnS electrode corresponding continual potential increases 62
Fig. 16. Microstructural analysis before and after 20 hr CO₂ conversion 62
Fig. 17. XPS spectra of S 2p peaks before and after a CO₂ER stability test 63
Fig. 18. CO₂ conversion behavior of (a) Zn foil and (b) TU-ZnS electrode corresponding continual potential increases. 64