Development and investigation of non-Pt cathode catalysts for polymer electrolyte membrane fuel cells고분자 전해질 막 연료전지용 비 백금 양극 촉매의 개발 및 연구

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Alternatives for Pt-based catalysts for oxygen reduction reactions (ORRs) in polymer electrolyte membrane fuel cells (PEMFCs), various non-Pt catalysts were synthesized and characterized. In the acidic media, non-Pt catalysts show relatively much lower ORR activity and stability compared to Pt-based cata-lysts; therefore, improving their performance is one of the major challenges for commercializing PEMFCs. In this study, two different types of alternative catalysts were investigated. One is the Pd-based catalysts and the other is the heteroatom-doped carbon catalysts. To improve the performance of the catalysts, diverse ap-proaches were attempted by metal oxide decorations, morphological modifications, changing precursors, and controlling doping amount or type. Decorations of Pd nanoparticles with Mn3O4 were investigated. The catalysts were prepared by polyol reduction of Pd(acac)2 and thermal decomposition of Mn2(CO)10. Surface composition and structure of the particles were varied depending on the injection temperature of Mn2(CO)10 and were closely related to the electrochemical properties. The presence of Mn3O4 promoted the performance towards ORRs by facilitating oxygen transfer to the active sites of Pd. Through an accelerated degradation test (ADT), nanoparticles with a Pd-rich shell were obtained by dissolution of surface exposed Mn3O4 and at 0.57 V (vs. Ag/AgCl) this catalyst showed the highest activity towards ORRs, a 149 % in mass activity and 142 % in specific activity compared to that of Pd/C. N-doped CNTs grafted on Vulcan carbon were synthesized by pyrolyzing dicyandiamide (DCDA) on carbon supported iron oxide at 700, 800, and 900 oC. The effects of pyrolysis temperature on ORRs were investigated. After pyrolysis, newly generated carbon arising from DCDA was observed in all the catalysts. Especially at 900 oC, CNTs were grown catalyzed by Fe2O3/C. Pyrolysis of DCDA at higher temperatures in-creased ORR activity significantly. The catalyst exhibi...
Advisors
Woo, Seong-Ihlresearcher우성일
Description
한국과학기술원 : 생명화학공학과,
Publisher
한국과학기술원
Issue Date
2012
Identifier
511834/325007  / 020097116
Language
eng
Description

학위논문(박사) - 한국과학기술원 : 생명화학공학과, 2012.8, [ xi, 171 p. ]

Keywords

Polymer electrolyte membrane fuel cells; oxygen reduction reactions; non-Pt catalysts; Pd; 고분자 전해질 막 연료전지; 산소환원반응; 비 백금 계 촉매; 팔라듐; 탄소; Carbon

URI
http://hdl.handle.net/10203/179901
Link
http://library.kaist.ac.kr/search/detail/view.do?bibCtrlNo=511834&flag=dissertation
Appears in Collection
CBE-Theses_Ph.D.(박사논문)
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