폐고분자 업사이클링을 통한 질소 도입 탄소 지지체의 합성과PEMFC 응용에 대한 연구 = Upcycling Waste Polymers into Nitrogen-Doped Carbon Supports for PEMFC

다국어 초록 (Multilingual Abstract)

Global environmental pollution and greenhouse gas emissions have increased, driving the demand for environmentally benign energy conversion technologies. Among them, hydrogen-based technologies have attracted significant attention as low-emission power-generation systems. Hydrogen fuel cells directly convert the chemical energy of hydrogen and oxygen into electrical energy via electrochemical redox reactions, producing water as the only byproduct. Polymer electrolyte membrane fuel cells (PEMFCs) are widely considered promising for transportation applications owing to their low operating temperature, high power density, and rapid startup capability. However, PEMFC performance is largely governed by the cathodic oxygen reduction reaction (ORR), and the intrinsically
ORR kinetics lead to large activation overpotentials and voltage losses under practical operating conditions, thereby limiting further improvements in efficiency and power output. Platinum (Pt)-based catalysts are typically employed to mitigate these activation losses. However, the high cost and limited abundance of Pt remain major barriers to large-scale commercialization. In addition, during prolonged operation, Pt catalysts undergo degradation processes such as dissolution, particle growth, agglomeration, and detachment from the carbon support. Carbon corrosion can further accelerate performance decay, resulting in a loss of active sites (or electrochemically active surface area) and deteriorated durability. In this study, nitrogen-doped carbon supports derived from waste polystyrene were developed and evaluated as Pt catalyst supports for PEMFCs. Nitrogen-doped hyper-crosslinked polymer precursors were synthesized via a Friedel–Crafts reaction using pyrrole, followed by carbonization to produce the carbon supports. The resulting supports exhibited a porous structure including mesopores, and nitrogen doping adjusted the electronic structure of the carbon surface while improving ionomer–support interactions. Based on these supports, Pt/NCPS catalysts were prepared and evaluated in H2/O2 single cells. Pt/N0.5CPS delivered improved performance over commercial Pt/C at the same Pt loading, achieving
a mass activity of 0.24 A mgPt-1 at 0.9 V and a maximum power density of 1174.6 mW cm-2. In addition, after 30,000 cycles of an accelerated stress test, Pt/N0.5CPS retained 65.4% of its initial power density. These results demonstrate that tailoring the structural and electrical properties of nitrogen-doped carbon supports can improve both the activity and durability of PEMFC catalysts, highlighting the potential of waste plastic–derived carbon supports for PEMFC
applications.

목차 (Table of Contents)

• Chapter 1. General Introduction 1
• 1.1. 수소 연료전지 1
• 1.2. 연료전지 종류 2
• 1.2.1. 고분자 전해질 연료전지 (PEMFC) 3
• 1.2.2. 알칼리 연료전지 (AFC) 4
• 1.2.3. 인산형 연료전지 (PAFC) 4
• 1.2.4. 용융 탄산염 연료전지 (MCFC) 5
• 1.2.5. 고체산화물 연료전지 (SOFC) 6
• 1.3. PEMFC 구성요소 8
• 1.3.1. 막 전극 접합체 (Membrane Electrode Assembly, MEA) 10
• 1.3.2. 산소 환원 반응 (Oxygen Reduction Reaction, ORR.) 11
• 1.3.3. 삼상계면 (Triple Phase Boundary, TPB) 13
• 1.4. 작동전압 16
• 1.4.1. 활성화 과전압 (Activation Overpotential) 17
• 1.4.2. 저항 과전압 (Ohmic Overpotential) 17
• 1.4.3. 물질 전달 과전압 (Mass Transport Overpotential) 18
• 1.5. 연료전지에서 탄소 지지체의 역할 20
• 1.5.1. 탄소 지지체 20
• 1.5.2. 탄소 지지체 열화 21
• 1.6. 탄소 지지체 구조 설계 전략 23
• 1.6.1. 고온 열처리 23
• 1.6.2. 이종원소 도입 24
• Chapter 2. PEMFC 용 질소 도입 탄소 지지체의 제조 및 특성 분석 26
• 2.1. 연구배경 26
• 2.2. 실험 32
• 2.3. 실험 방법 32
• 2.3.1. 탄소 지지체 합성 32
• 2.3.2. 백금 촉매 담지 33
• 2.3.3. MEA 제조 방법 33
• 2.3.4. 소재 특성 분석 37
• 2.3.5. 전기화학적 특성분석 38
• 2.4. 결과 및 고찰 39
• 2.4.1. 탄소 소재 합성 및 백금 촉매 담지 39
• 2.4.2. W-PS 의 초가교화 및 질소 도입에 따른 열분해 거동 및 탄화 특성 40
• 2.4.3. W-PS 의 초가교화 및 탄화에 따른 구조 변화 49
• 2.4.4. 질소 도입량에 따른 탄소 구조 및 기공표면 특성 변화 55
• 2.4.5. 촉매 특성 분석 62
• 2.4.6. 전기화학 특성 분석 67
• 2.5. 결 론 77
• References 79