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First-principles thermodynamic study on the electrochemical stability of Pt nanoparticles in fuel cell applications

Title
First-principles thermodynamic study on the electrochemical stability of Pt nanoparticles in fuel cell applications
Translated Title
제일원리전산을 이용한 연료전지용 백금 나노촉매의 전기화학적 안정성에 대한 열역학적 분석
Authors
Seo, Joon Kyo
DGIST Authors
Seo, Joon Kyo; Han, Byung Chan
Advisor(s)
Han, Byung Chan
Co-Advisor(s)
Yoon, Young Gi
Issue Date
2013
Available Date
2016-05-18
Degree Date
2013. 2
Type
Thesis
Keywords
Density functional theoryFuel cellNanocatalystStabilityDegradation mechanism제일원리전산연료전지나노입자내구성열화메커니즘
Abstract
Durability of Pt based nanocatalyst materials in acidic environments is one of the key issues hindering the development of efficient fuel cells. In this study, we used first principles calculations to analyze the electrochemical degradation of Pt nanoparticles. Model systems for Pt nanoparticles of different sizes were conceptualized for calculating their electrochemical dissolution potential, which essentially indicates the nanoparticle’s resistance to dissolution. We adopted a step by step mechanism for dissolution of Pt atoms on the outermost shell of the nanoparticle by accounting for various possible pathways which lead to complete dissolution. Based strictly on thermodynamic considerations, our findings point towards a strong size dependent behavior of the Pt nanoparticles, whose properties become similar to bulk Pt for size more than 3 nm. Remarkably, we find that for all cases, the dissolution proceeds by exposing more (111) facets at the expense of other atomic sites. Our results indicate that the competition between two major thermodynamic factors, the cohesive energy and the surface energy, decides the dissolution pathway. Based on our findings, we propose some desired characteristics which can serve towards rational design of model Pt nanocatalysts. Our findings may be of importance in understanding of the electrochemical stability in other applications as well, for instance the photo-catalysts for fuel generations via water splitting. ⓒ 2013 DGIST
Table Of Contents
Chapter 1. Introduction 1 -- 1.1 Challenges of fuel cells 1 -- 1.2 Objectives of this work 2 -- Chapter 2. Methodology 4 -- 2.1 Model systems 4 -- 2.2 Computational details 7 -- 2.3 Formalisms 8 -- Chapter 3. Results and discussion 10 -- Chapter 4. Limitations of the thesis and future works 17 -- Chapter 5. Conclusions 19 -- References 21 -- Summary (국문요약) 25
URI
http://dgist.dcollection.net/jsp/common/DcLoOrgPer.jsp?sItemId=000002262498
http://hdl.handle.net/20.500.11750/1327
DOI
10.22677/thesis.2262498
Degree
Master
Department
Energy Systems Engineering
University
DGIST
Files:
Collection:
Energy Science and EngineeringThesesMaster


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