Title Page
Contents
ABSTRACT 10
Ⅰ. Introduction 12
1.1. Green Hydrogen : A beacon in renewable energy Solutions 12
1.2. Direction for PEMWE development 13
1.3. Strategies for enhancing PEMWE efficiency 13
1.3.1. Self-supported catalyst using electrodeposition 13
1.3.2. Chemical composition design 15
Ⅱ. Materials and Methods 16
2.1. Chemicals 16
2.2. Materials Synthesis 16
2.2.1. Preparation of Titanium mesh(TM) supports 16
2.2.2. Preparation of electrolyte of NiIr and NiIr Re 16
2.2.3. Synthesis of NiIr and NiIr Re onto TM 17
2.3. Materials Characterizations 17
2.4. Electrochemical Measurements 18
2.4.1. Three-electrode electrochemical measurement 18
2.4.2. Calculation of turnover frequency (TOF) 19
2.4.3. Calculation of Activation energy (Ea) 20
2.4.4. Calculation of electrochemical double layer capacitance (Cdl)[이미지참조] 20
2.4.5. Calculation of electrochemical surface area (ECSA) 20
2.4.6. Calculation of Faradaic efficiency(FE) using gas chromatography 21
2.5. Computational methods 21
Ⅲ. Results and discussion 24
3.1. Material characterizations 24
3.2. Electrochemical performance 32
3.3. DFT calculation 42
Ⅳ. Conclusion 51
References 53
Abstract (in Korean) 57
Table. 1. The calculated lattice parameters of cubic Ir comparison with previous papers 43
Table. 2. The Calculated overpotential with respect to the structure and plane of metal iridium 45
Table. 3. The calculated lattice parameters of Rutile IrO₂ comparison with previous papers 48
Table. 4. The Calculated overpotential for OER of IrO₂ (110) 50
Figure. 1. a) conventional powder catalysts on GC electrode with binders. b) self-supported catalyst of binder free electrode. 14
Figure. 2. FE-SEM images of a) Titanium mesh, b) Iridium₁₀₀, c) NiIr, d) NiIr Re, e) NiIr after OER and f) NiIr Re after OER. g) XRD Pattern of NiIr Re... 24
Figure. 3. Morphology and structure of NiIr and NiIr Re. a, b, d, e) of NiIr and h, I, k, l) of NiIr Re of TEM images; c,j) SAED pattern of NiIr, NiIr Re; f, g, m... 26
Figure. 4. Morphology and structure of NiIr and NiIr Re after OER. a and c) TEM image and the right outsets demonstrate the corresponding SAED. b and... 28
Figure. 5. Characterization for electronic properties. a) XPS of a) Ir 4f, b) Ni 2p, c) O1s and d) Re 4f. 29
Figure. 6. Characterization for electronic properties. XANES of a, d) Ir L₃-edge, b) Re L₂-edge, c) Ni K-edge, e, f) O K-edge utilizing TEY and FY,... 30
Figure. 7. LSV curves for NiIr Re with (a) different Ir amounts, (b) different Ni amounts and (c) different Re amounts. 33
Figure. 8. Characterization for electrochemical properties of NiIr Re. a) LSV polarization curves. b) the corresponding Tafel plots. C)EIS of the... 34
Figure. 9. Characterization for electrochemical properties of NiIr Re. CV scans for calculating Cdl (a) NiIr, (b) NiIr Re and (c) IrO₂, respectively. D)...[이미지참조] 36
Figure. 10. Characterization for electrochemical properties of NiIr Re. (a) CV curves of electrocatalysts (b) Utilizing a short CV profile of electrocatalysts,... 38
Figure. 11. Characterization for electrochemical properties of NiIr Re. a) TOFs NiIr Re in comparison tested catalysts at an overpotential of 250mV. 38
Figure. 12. LSV curves of (a) NiIr, (b) NiIr Re, and (c) IrO₂ measured at different temperatures 39
Figure. 13. Characterization for electrochemical properties of NiIr Re. a) Arrhenius plot for determining activation energy for the acidic OER 39
Figure. 14. Electrochemical catalytic properties a) LSV polarization curves measured for HER in 0.1M HClO4 using a scan rate of 5mV/s. b) Polarization... 40
Figure. 15. Electrochemical catalytic properties. LSV of NiIr Re for OER, HER in a) 1M KOH, b) 1M KOH + 0.5M NaCl and c) 1M PBS. 41
Figure. 16. DFT Calculation. a) Bulk structure of Catalyst. Cohesive energy of NiIr and NiIr Re b) Ni concentration, c) Re concentration. d) Phase... 42
Figure. 17. DFT calculations. a) Side view of atomic configurations for metallic Ir slab models. b) Pourbaix diagram for metallic Ir surfaces c)... 44
Figure. 18. DFT calculations. a) Top view and side view of optimized IrO₂ (110) structure. b) Re doping formation energy c) Atomic configurations of... 47
Figure. 19. DFT calculations. a) VIr formation energy b) Optimized atomic configurations of IrO₂ (110) with Ir vacancies. c) Pourbaix diagram of IrO₂ (110)...[이미지참조] 49