Nanotube Buckypaper Electrodes for PEM Fuel Cell Applications Chung-Lin Ku
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Florida State University Libraries Electronic Theses, Treatises and Dissertations The Graduate School 2007 Nanotube Buckypaper Electrodes for PEM Fuel Cell Applications Chung-Lin Ku Follow this and additional works at the FSU Digital Library. For more information, please contact [email protected] THE FLORIDA STATE UNIVERSITY COLLEGE OF ENGINEERING NANOTUBE BUCKYPAPER ELECTRODES FOR PEM FUEL CELL APPLICATIONS By CHUNG-LIN KU A Thesis submitted to the Department of Industrial and Manufacturing Engineering in partial fulfillment of the requirements for the degree of Master of Science Degree Awarded: Fall Semester, 2007 The members of the committee approve the thesis of Chung-Lin Ku defended on November 06, 2007. ______________________________ Zhiyong Liang Professor Directing Thesis ______________________________ Jim P. Zheng Outside Committee Member __________________________________ Ben Wang Committee Member ______________________________ Chuck Zhang Committee Member Approved: __________________________________________________________ Chuck Zhang, Chair, Department of Industrial and Manufacturing Engineering __________________________________________________________ Ching-Jen Chen, Dean, FAMU-FSU College of Engineering The Office of Graduate Studies has verified and approved the above named committee members. ii BIOGRAPHICAL SKETCH Chung-Lin (Daphne) Ku is currently a master’s student in Industrial Engineering at FAMU-FSU College of Engineering and expecting graduation in December, 2007. She was born in October of 1982. She received her Bachelor’s of Engineering in Industrial Engineering in June 2005 from Tung-Hai University at Tai-Chuang, Taiwan. Her research interests include nanotube technologies, design of experiments, supply chain management, quality control, reliability, and applied optimization. Her favorite hobbies include badminton, music and movies. She is looking forward to pursue a career in the field of Industrial Engineering. For more information, please feel free to contact her at [email protected]. 72 TABLE OF CONTENTS List of Tables.....................................................................................................................vi List of Figures..................................................................................................................vii Abstract...............................................................................................................................x CHAPTER 1 INTRODUCTION......................................................................................1 1.1 Motivation......................................................................................................................2 1.2 Problem Statement.........................................................................................................3 1.3 Research Objectives...........................................................................................…........4 CHAPTER 2 LITERATURE REVIEWS........................................................................6 2.1 Introduction of Fuel Cells…………………………………………………….……….6 2.1.1 Principle..............................................................................................................6 2.1.2 Types of Fuel Cells..............................................................................................8 2.1.3 Proton Exchange Membrane Fuel Cells (PEMFCs)..........................................9 2.1.4 Electrodes.........................................................................................................10 2.2 Carbon Nanotube (CNT) and Nanofiber (CNF)..........................................................13 2.2.1 Good Candidates for Catalyst Supports……………………………………..13 2.2.2 CNT Buckypaper……………….…………………………………….………16 2.3 CNT Application Studies in PEMFCs.........................................................................19 2.3.1 Synthesis Methods for Pt/ CNT Electrocatalysts..............................................20 2.3.2 CNT Supports for PEMFC Catalysts................................................................24 2.4 Conclusion...................................................................................................................29 CHAPTER 3 EXPERIMENTAL………...….................................................................31 3.1 Preparation of Mixed CNT Buckypapers....................................................................31 3.1.1 Fabrication Methodology.................................................................................31 3.1.2 Characterization Methods................................................................................33 3.2 Preparation of Pt/BP Electrodes..................................................................................33 3.2.1 Electrodepositions of Pt Nanoparticles............................................................33 3.2.2 Electrochemical and Structural Analyses of Pt/BP Samples………................36 CHAPTER 4 RESULTS AND DISCUSSION...............................................................38 4.1 Surface Morphology of Pt/Mixed BP Electrodes.....................................................38 4.1.1 SEM Analysis of the Specimens…………........................................................38 iv 4.1.2 XRD Analysis of the Specimens........................................................................45 4.2 Electrocatalytic Properties of Pt/Mixed BP Electrodes................................................47 4.2.1 Pt Specific Surface Area...................................................................................47 4.2.2 Pt Utilization Analysis......................................................................................52 4.3 Effects of Mixed BPs Nanostructure on Pt Deposition……........................................54 4.4 Cost Analysis................................................................................................................54 4.5 Ideal Electrode Microstructure for PEMFC.................................................................58 CHAPTER 5 CONCLUSIONS.......................................................................................61 CHAPTER 6 FUTURE WORKS....................................................................................62 REFERENCES.................................................................................................................63 BIOGRAPHICAL SKETCH..........................................................................................72 v LIST OF TABLES Table 2.1 Pore channel types and composition in the negative of H2/O2 fuel cell............10 Table 2.2 Current Pt loading of anode and cathode......................................................….12 Table 2.3 Adsorption properties of CNT, CNF, and carbon black……………………....15 Table 2.4: BET surface area analyzer………………………………………………........18 Table 2.5: Electrical conductivity of mixed buckypapers……………………………….18 Table 2.6 Summarization of synthesis methods for CNT-supported Pt electrocatalysts...24 Table 2.7 Summarization of Pt particle size on CNT supports by electrodeposition……29 Table 3.1 The weight ratio information of all buckypaper samples……………………..33 Table 4.1 Pt particle size calculated by Debye-Scherrer formula……….………...……..46 Table 4.2 Material cost analysis………………………………………………………….55 Table 4.3 Theoretical Pt loadings of Pt/S89M72 BP…………………………………….55 Table 4.4 Prediction of material cost in 2010 and 2020…………………………………57 vi LIST OF FIGURES Figure 1.1 Scheme of platinum on carbon support..............................................................4 Figure 2.1 Scheme of a fuel cell and basic operating principles.........................................7 Figure 2.2 The components of a single PEM fuel cell.......................................................10 Figure 2.3 Electrode structure of a conventional design and SEM micrograph of carbon cloth (GDL)……………………………………………………………………................11 Figure 2.4 Schematic configuration of the MEA………………………………………...12 Figure 2.5 Schematic representations of nanotube and nanofiber structures………..…...14 Figure 2.6 SWNT buckypaper, TEM image of SWNT powder, and SEM images of SWNT buckypaper surface……………..………………………………………………..17 Figure 2.7Scheme of the structures of a MWNT and a carbon black particle, and their structures after electrochemical oxidation; comparison of Pt active surface area loss for the case of Vulcan XC-72 and MWNT during oxidation treatment……………….…….19 Figure 2.8 Typical synthesis process and explanation of Pt/ CNT catalyst by the chemical reduction method………………………...………………………………………………20 Figure 2.9 SEM micrograph of carbon cloth after impregnation, and SEM image of the surface of a Pt-sputtered GDE with an equivalent film of thickness of 3 nm…………...21 Figure 2.10 The synthesis procedure for Pt/CNT catalysts by microwave heated polyol process……………………………………………………………………………………22 Figure 2.11 Schematic diagram of three-step electrochemical synthesis of Pt particles on CNTs…………...……………………………………………………………...…………23 Figure 2.12 SEM image of the well-aligned carbon nanotube arrays on Ti substrate…...25 2.13 Chronoamperometric curves for 30wt% Pt/Vulcan XC-72, 30wt% Pt/MWNT, Vulcan XC-72, and MWNT……………………….…………………………...………...26 Figure 2.14 TEM micrographs and histogram of Pt particle size distribution on Pt/Vulcan XC-72 and Pt/MWNTs before and after durability test….…………...………………….27 vii Figure 2.15 Electrical conductivity as a function of thickness for SWNT papers……….27 Figure 2.16 SEM images of an in-house prepared