아주대학교

목차

1. Chapter 1: Introduction 1
1.1. Global Energy Crisis and Green Hydrogen 1
1.2. Photoelectrochemical and Electrocatalytic Water Splitting 2
1.2.1. Photoelectrochemical Water Splitting 2
1.3. Challenges of Cu2O Photocathodes and Transition Metal Sulfides 5
1.4. Atomic-Scale Defect and Heterostructure Engineering 6
1.5. Research Objectives and Hypothesis 8
1.5.1. Central hypothesis of this dissertation 9
1.6. Thesis Organization 9
2. Chapter 2: Technical Overview of Photocathodes and Transition Metal Chalcogenides 12
2.1. Semiconductor Photo-electrochemistry 12
2.1.1. Band structure and charge transport 12
2.1.2. Band bending and semiconductor/electrolyte interface 12
2.1.3. Charge Recombination Mechanisms 13
2.2. Cu2O-Based Photocathodes 14
2.2.1. Structural and Electronic Properties of Cu2O 14
2.2.2. PEC hydrogen evolution using Cu2O 15
2.2.3. Surface Passivation Strategies 15
2.2.4. Heterostructure Engineering Approaches 16
2.2.5. Cocatalysts and Conductive Interlayers 17
2.3. Interface and Surface Engineering Techniques 17
2.3.1. Electrodeposition 17
2.3.2. RF Magnetron Sputtering 18
2.3.3. Atomic Layer Deposition （ALD） 19
2.3.4. Electrophoretic Deposition （EPD） 19
2.3.5. Reactive Ion Etching （RIE） 20
2.4. Transition Metal Sulfides for HER 21
2.4.1. Fundamentals of HER Electrocatalysis 21
2.4.2. Ni-Mo Sulfides 21
2.4.3. V-Mo and Mo‑V Bimetallic Sulfides 22
2.4.4. Bimetallic Synergistic Effects 23
2.5. Defect and Doping Engineering in Sulfides 24
2.5.1. Sulfur Vacancies and Active Sites 24
2.5.2. Electronic Modulation Through Doping 25
2.5.3. Conductivity Enhancement Strategies 25
2.5.4. Catalytic Reaction Mechanisms 26
3. Chapter 3: Advanced Cu2O‑Based Heterostructured Photocathodes for Efficient and Stable PEC Hydrogen Evolution 27
3.1. FeOOH/Cu2O/HfO2/MoOx Photocathodes for PEC Hydrogen Evolution 27
3.1.1. Introduction 27
3.1.2. Experimental Section 29
3.1.3. Results and Discussion 31
3.1.4 Summary 44
3.2. Cu2O/SnO2/rGO/FeNiOOH Photocathodes with RIE Surface Engineering 45
3.2.1. Introduction 45
3.2.2. Experimental Section 47
3.2.3. Results and Discussion 48
3.2.4. Summary of Section3.2 65
4. Chapter 4: Transition from PEC to electrolysis: Indium-Doped Ni-Mo Bimetallic Sulfides for HER 66
4.1 Introduction 66
4.2 Experimental Section 68
4.2.1 Chemicals 68
4.2.2 Synthesis of NMS‑4 and In‑Doped NMS‑4 68
4.2.3 Electrochemical Analysis 69
4.2.4 Characterization Techniques 70
4.3 Results and Discussion 71
4.3.1 Structural and Morphological Characterization 71
4.3.2 HER Performance in Alkaline Medium （1M KOH 80
4.3.3 HER Performance in Acidic Medium （0.5M H2SO4） 82
4.3.4 DFT Analysis 85
4.4 Summary of Chapter 4 88
5. Chapter 5: Co-Doped V-Mo and Mo-V Bimetallic Sulfides for HER 90
5.1 Introduction 90
5.2 Experimental Section 92
5.2.1 Chemicals 92
5.2.2 Synthesis of VMS‑3, MVS‑2, Co‑doped VMS‑3, and Co‑doped MVS‑2 92
5.2.3 Electrochemical Measurements 94
5.3 Results and Discussion 94
5.3.1 Morphological and Structural Characterization 94
5.3.2 X‑ray Diffraction Analysis 99
5.3.3 Transmission Electron Microscopy （TEM） and HRTEM （To be added） 101
5.3.4 X‑ray Photoelectron Spectroscopy （XPS） 101
5.3.5 HER Performance in Acidic Medium （0.5M H2SO4） 105
5.3.6 HER Performance in Alkaline Medium （1M KOH） 107
5.3.7 Density Functional Theory （DFT） Analysis （To be added） 109
5.4 Summary of Chapter 5 110
6. Chapter 6: Conclusions and Future Perspectives 111
6.1 Major Findings 111
6.2 Scientific Contributions 112
6.3 Future Research Directions 113
Bibliography 115