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First Principles Study of Morphology, Doping Level and Water Solvation Effects on Catalytic Mechanism of a Graphene Towards Oxygen Reduction Reaction

Title
First Principles Study of Morphology, Doping Level and Water Solvation Effects on Catalytic Mechanism of a Graphene Towards Oxygen Reduction Reaction
Translated Title
제 1 원리 전산을 이용하여 모폴로지, 도핑농도, 용매가 그래핀에서 산소환원반응에 미치는 영향 분석
Authors
Kwak, Do Hyun
DGIST Authors
Kwak, Do Hyun; Han, Byung Chan
Advisor(s)
Han, Byung Chan
Co-Advisor(s)
Yoon, Young Gi
Issue Date
2015
Available Date
2015-01-12
Degree Date
2015. 2
Type
Thesis
Keywords
First principlesRenewable energyGrapheneCatalystOxygen reduction reaction제 일 원리신 재생에너지그래핀촉매산소환원반응
Abstract
First principles density functional theory calculations are utilized to unveil oxygen reduction reaction mechanisms on nitrogen doped graphene (N-Gr). Considering the effect of both the geometry and concentration of N in bulk and edge N-Gr forms, we calculate the energies of a large number of model systems to cover a wide range of possible N-Gr structures and determine the most stable ones. In agreement with experiments, our calculations suggest that doping levels in stable N-Gr forms are limited to less than about 30 at.%, above which the hexagonal graphene framework is broken. Remarkably, the ground state structures of bulk and edge N-Gr are found to differ depending on the doping level and poisoning of the edge bonds. ORR mechanisms are estimated using Gibbs free energy diagrams, both with and without water solvation. Our results indicate that N doping significantly alters the catalytic properties of pure graphene and that dilutely doped bulk N-Gr forms are the most active. ⓒ 2015 DGIST
Table Of Contents
1. Introduction 1-- 1.1. Introduction to First principles DFT calculations 1-- 1.2. Background 1-- 2. Methodology and Model Systems 3-- 2.1. Computational Details 3-- 2.2. DFT calculations of stable N-Gr Structures 4-- 2.3. Poisoning of dangling bonds in edge N-Gr 6-- 3. Results and Discussion 11-- 3.1. Electronic structures of N-Gr model systems 11-- 3.2. Thermodynamic free energy diagram of ORR: Formalism 12-- 3.3. Gibbs free energy diagrams for ORR: The effect of dopant concentration 13-- 3.4. Thermodynamic free energy diagram of ORR: Effect of water solvation 18-- 4. Conclusion 20-- References 21-- Summary(국문요약) 25-- Acknowledgement 26-- Curriculum Vitae 27
URI
http://dgist.dcollection.net/jsp/common/DcLoOrgPer.jsp?sItemId=000001923020
http://hdl.handle.net/20.500.11750/1374
DOI
10.22677/thesis.1923020
Degree
Master
Department
Energy Systems Engineering
University
DGIST
Files:
Collection:
Energy Science and EngineeringThesesMaster


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