PEM 연료전지용 AuPt/C 및 AuPtRu/C 복합촉매의 합성과 전기화학적 촉매특성 연구 = Synthesis and Electrochemical Catalytic Properties of AuPt/C and AuPtRu/C Nano Composite Catalysts for PEM Fuel Cell

다국어 초록 (Multilingual Abstract)

Electrocatalysts based on platinium are the best materials for the anodic oxidation of PEM fuel cell and the cathodic reduction of oxygen at low temperature. In this work, AuPt and AuPtRu composite nanoparticles with core-shell structure were synthesized by precipitation method, and these composite nanoparticles were loaded on carbon black for applying to the electrode of fuel cell.
In order to synthesize AuPt and AuPtRu composite nanoparticles, firstly, Au nanoparticles of 25~35nm size was pre-synthesized by Au seed-mediated growth method. And then, in case of AuPt nanoparticles were prepared by adding H₂PtCl_(6) solution and methanol(reducing agent) into Au colloid. And in case of AuPtRu nanoparticles were prepared by adding H₂PtCl_(6) solution, RuCl3 solution and methanol into Au colloid. Then, in the same way, the mixtures were boiled for 15 minute under vigorous stirring and then cooled to room temperature for 10 minute with vigorous stirring.
The synthesized AuPt and AuPtRu composite nanoparticles have a core-shell structure. The size of Au nanoparticles was 25~35nm, and the size of Pt and Ru nanoparticles on Au nanoparticles were 2~5nm.
For synthesis of AuPt/C and AuPtRu/C composite catalysts, this experimental procedure is similar with AuPt and AuPtRu composite nanoparticles. Breifly, fistly, Au colloid was prepared and then, in case of AuPt/C catalysts, carbon black, H₂PtCl_(6) solution and methanol(reducing agent) were added into Au colloid. And in case of AuPtRu/C catalysts, carbon black, Pt stock solution, Ru stock solution and methanol were added, respectively. After that, the mixtures were boiled for 15 minute under vigorous stirring and then cooled to room temperature for 10 minute with vigorous stirring.
The synthesized AuPt/C and AuPtRu/C composite catalysts with different compositions were investigated by transmission electron microscopy(TEM), UV-visible spectroscopy, X-ray diffraction (XRD) and cyclic voltammetry(CV).
AuPt/C composite catalysts are synthesized with different concentrations of Pt. The concentration of Pt was 10wt.%, 20wt.%, 40wt.% and 60wt.%(0.19, 0.38, 0.76 and 1.14mM). The results of CV revealed that the AuPt/C composite catalyst with 40wt.% Pt had high performance because of highest current density at 0.8V. From this results, we can say that Au nanoparticles accelerate methanol oxidation on the surface of Pt catalyst. The AuPt/C composite catalyst with 60wt.% Pt had lower current density than 40wt.%. Because the loaded Pt nanoparticles were strongly agglomerated on the surface of gold nanoparticles.
AuPtRu/C composite catalysts were synthesized with differnent Pt:Ru ratio at 40wt.% of the Pt loading amount. The Ru ratio was changed from 25% to 100% on the basis of Pt weight. In the CV results, the AuPtRu/C composite catalyst with 50% Ru showed the highest electrochemical activity. The first peak of methanol oxidation of the sample with 50% Ru appeared at 70V and the current density was lower than AuPt/C composite catalyst because of the characteristic of PtRu/C catalyst.

목차 (Table of Contents)

• 제 1장 서론 = 1
• 제 2장 이론적 배경 = 6
• 2-1 연료전지 및 연료전지 단위 셀의 구조 = 6
• 2-1-1 PEMFC(Polymer Electrolyte Membrane Fuel Cell) = 6
• 2-1-2 MEA(Membrane Electrode Assembly)의 구조 = 7
• 2-2 Cyclic Voltammetry = 9
• 2-3 Pt/C 촉매의 전기화학적 거동 = 16
• 제3장 실험방법 = 19
• 3-1 시약 및 재료 = 19
• 3-2 Au 콜로이드의 합성 = 22
• 3-3 AuPt 및 AuPtRu 복합나노입자 합성 = 25
• 3-3-1 AuPt 복합나노입자 합성 = 25
• 3-3-2 AuPtRu 복합나노입자 합성 = 25
• 3-4 AuPt 및 AuPtRu 복합나노입자 담지 carbon black의 제조 = 26
• 3-5 특성 분석 = 30
• 3-5-1 형상 및 입경 관찰 = 30
• 3-5-2 광학적 특성 평가 = 30
• 3-5-3 결정구조 및 정성분석 = 30
• 3-5-4 복합나노입자 촉매의 전기화학적 활성평가 = 31
• 제4장 결과 및 고찰 = 33
• 4-1 Au 콜로이드의 합성 = 33
• 4-2 화학적 환원법에 의한 AuPt 및 AuPtRu 복합나노입자 합성 = 35
• 4-2-1 AuPt 복합나노입자의 담지 형상에 미치는 Pt 농도의 영향 = 35
• 4-2-2 Pt 농도에 따른 AuPt 복합나노입자의 결정구조 분석 = 36
• 4-2-3 AuPt 복합나노입자의 형상에 미치는 환원제 양의 영향 = 36
• 4-2-4 AuPtRu 복합나노입자의 형상에 미치는 Ru 농도의 영향 = 38
• 4-2-5 Ru 농도에 따른 AuPtRu 복합나노입자의 결정구조 분석 = 38
• 4-3 PEMFC용 AuPt/C 복합촉매의 제조 = 50
• 4-3-1 AuPt/C 복합촉매의 형상에 미치는 Pt 농도의 영향 = 50
• 4-3-2 AuPt/C 복합촉매의 전기화학적 활성평가 = 50
• 4-4 PEMFC용 AuPtRu/C 복합촉매의 제조 = 52
• 4-4-1 AuPtRu/C 복합촉매의 형상 = 52
• 4-4-2 AuPtRu/C 복합촉매의 전기화학적 활성평가 = 52
• 제 5장 결론 = 59
• 참고문헌 = 61