스피넬 구조 촉매 ZnCo2O4를 이용한 전극의 전기화학적 성능 평가

다국어 초록 (Multilingual Abstract)

With the world facing numerous climate and environmental challenges due to the use of fossil fuels, a global shift towards a net-zero policy and the adoption of environmentally friendly energy systems by 2050 is imperative. Hydrogen has emerged as a promising solution, serving as a clean and infinite fuel source with zero emissions when utilized. Hydrogen energy, known for its high energy density and long-term storage capabilities, is currently under extensive research in storage and application technologies. Green hydrogen, produced through water electrolysis, is considered the cleanest method of generating hydrogen. However, the oxygen evolution reaction, which requires four electrons for reduction, exhibits a higher overpotential than the hydrogen evolution reaction, hindering smooth electrolysis. Extensive research is being conducted on catalysts to facilitate efficient electrolysis. In this study, we synthesized catalysts modified with zinc and conducted electrochemical analyses to enhance our understanding of their performance in the context of water electrolysis. Initially, the catalyst was synthesized through hydrothermal synthesis under high-temperature and high-pressure conditions. Subsequent annealing processes were performed to ensure thermal stability and achieve fine particle size. Various analytical techniques such as XRD, XPS, FT-IR, Raman, BET, UPS, SEM, and TEM were employed to confirm the synthesis and characterize the catalyst. The results consistently demonstrated the superior performance of ZnCo2O4 compared to ZnO and Co3O4. Improved pore volume and diameter were observed, and ZnCo2O4 exhibited a structurally superior 2D nano-sheet morphology compared to the flake form of ZnO and the 1D nano-rod structure of Co3O4. This structural advantage is expected to lead to an increase in electrochemical surface area. To validate the electrochemical performance, we conducted an electrochemical analysis using the potential difference method after stabilizing the system to reduce the resistance between the electrode and electrolyte. A three-electrode system under alkaline electrolyte conditions (1M KOH) was selected, and cyclic voltammetry (CV) scans in the range of 20–100 mV/s were performed to calculate the electrochemical surface area. A 12% increase in surface area compared to Co3O4 was confirmed. Additionally, through electrochemical impedance spectroscopy (EIS) analysis, it was proven that the synthesized catalyst has the lowest charge transfer resistance, validating its role as an alternative catalyst to reduce overpotential. Based on the results above, the successful synthesis of an improved alternative catalyst has been achieved. This study demonstrates the electrochemical surface area to improve the performance of electrochemical devices. The Catalyst synthesized by adding Zinc exhibited an increased electrochemical surface area. Additionally, this concept will pave the way for the creation of electrochemical devices such as batteries and electrolyzers.

목차 (Table of Contents)

• Ⅰ. 서 론 1
• 1.1 연구 배경 1
• 1.2 연구 동향 2
• 1.3 연구 목적 7
• Ⅱ. 연구 이론 8
• 2.1 수전해 8
• 2.2 전극 10
• 2.2.1 기체 확산층 13
• 2.2.2 촉매층 16
• 2.3 화학분석법 17
• 2.3.1 순환 전압전류법(CV) 18
• 2.3.2 선형주사전위법(LSV) 18
• 2.3.3 전기화학 임피던스 분광법(EIS) 19
• 2.3.4 슈퍼커패시터(Supercapacitor) 19
• 2.3.5 X-선 회절 분석법(XRD) 20
• 2.3.6 X-선 광전자 분광법(XPS) 20
• 2.3.7 푸리에 변환 적외선 분광법(FT-IR) 21
• 2.3.8 라만 분광법(Raman Spectroscopy) 22
• 2.3.9 비표면적 및 기공분석 장치(BET) 23
• 2.3.10 자외선 광전자 분광법(UPS) 23
• 2.3.11 주사 전자 현미경(SEM) 25
• 2.3.12 투과 전자 현미경(TEM) 26
• Ⅲ. 실 험 28
• 3.1 실험 준비 28
• 3.1.1 촉매 합성 28
• 3.1.2 촉매 잉크 32
• 3.1.3 전극 32
• 3.2 장치 구성 34
• Ⅳ. 실험 결과 37
• 4.1 X-선 회절 분석법(XRD) 37
• 4.2 X-선 광전자 분광법(XPS) 40
• 4.3 푸리에 변환 적외선 분광법(FT-IR) 44
• 4.4 라만 분광법(Raman Spectroscopy) 46
• 4.5 비표면적 및 기공분석 장치(BET) 48
• 4.6 자외선 광전자 분광법(UPS) 50
• 4.7 주사 전자 현미경(SEM) 53
• 4.8 투과 전자 현미경(TEM) 55
• 4.9 선형주사전위법(LSV) 58
• 4.10 전기화학적 표면적(ECSA) 59
• 4.11 전기화학 임피던스 분광법(EIS) 62
• 4.12 슈퍼커패시터(Supercapacitor) 63
• Ⅴ. 결론 및 고찰 66
• Appendix 68
• 참고문헌 72