Nickel based electro oxidation catalysts for urea sensors and urea fuel cells doctor of philosophy major chemical and biological engineering

A thesis for the Degree of Doctor of Philosophy Nickel – based electro-oxidation catalysts for urea sensors and urea fuel cells By TRAN THAO QUYNH NGAN Department of Chemical and biological engineering Graduate School Gachon University A thesis for the Degree of Doctor of Philosophy Nickel – based electro-oxidation catalysts for urea sensors and urea fuel cells By TRAN THAO QUYNH NGAN Submitted in Fulfillment of the Requirements for the Degree of Doctor of Philosophy July, 2018 Department of Chemical and biological engineering Graduate School Gachon University Thesis for Doctor of Philosophy’s Degree Nickel – based electro-oxidation catalysts for urea sensors and urea fuel cells By TRAN THAO QUYNH NGAN Accepted in Fulfillment of the Requirements for the Degree of Doctor of Philosophy July 2018 Committee Chairman Young Soo Yoon Committee Member Hyon Hee Yoon Committee Member Ho Yu Yong Committee Member Il Tae Kim Committee Member Jae Seung Kim i ACKNOWLEDGEMENTS Firstly, I would like to express my sincere gratitude to my advisor, Prof Hyon Hee Yoon, for his tremendous guidance, support and continuous encouragement During my study for Ph.D course, he not only supported to me the best living and working environment, but also provided his guidance, with complete patience and motivation in the best condition for my research process All my achieved things are direct results of his nourishment of knowledge bestowed upon me during my study Furthermore, his encouragement and advice are the main motivation for me to overcome the difficulties of being a foreign student in Korea Especially, I’d like to give my appreciation to my laboratory members who are friendly beside me and give their hands to support me during this period Sincerely, I would like to thank all the academic and technical staff of department of Chemical and Biological Engineering, Gachon University for their support towards me in one way or another Finally, I would like to express my heartfelt gratitude to my parents who gave me a chance to every incredible thing and always give their continuous love, uninterrupted support and encouragement throughout the studying period here And, many thanks to all my friends who is a part of my life I want to you know I deeply cherish you and always will ii CONTENTS CHAPTER 1: RESEARCH AMBITION AND SIGNIFICANCE I.1 Urea sensor I.2 Direct urea fuel cell .5 I.3 Significance and organization CHAPTER 2: INTRODUCTION II Urea sensors .8 II 1.1 Enzymatic urea sensor II 1.2 Non-enzymatic urea sensor 10 II 1.3 Metal-organic frameworks (MOFs) 11 II 1.4 CeO2-modified perovskite oxide (LaNi0.6Fe0.4O3-CeO2) 12 II 1.5 The role of MWCNT in fabrication of urea sensor .14 II Direct urea fuel cell .14 II 2.1 Anode materials 20 II 2.2 Electrolyte materials 22 II 2.3 Cathode materials 23 II Modelling of DUFC 26 II 3.1 I-V behavior 26 II 3.2 Basic assumption and model structure 27 II 3.3 Mathematical model 32 II.3.3.1 Anode side 33 iii 3.3.1.1.Urea transport to gas diffusion layer (GDL): 33 3.3.1.2.Diffusion layer 33 3.3.1.3.Catalyst layer 35 II.3.3.2 Anion exchange membrane (AEM) 38 II.3.3.3 Ohmic overpotential 40 II.3.3.4 At cathode 43 3.3.4.1.Diffusion layer: .43 3.3.4.2.Catalyst layer: 44 II.3.3.5Solution procedure 45 3.3.5.1.Anode 46 3.3.5.2.Cathode 48 CHAPTER 3: EXPERIMENTAL SECTION 51 III Materials processing 51 III.1.1 LNF-C synthesized and electrode fabrication 51 III.1.2 Synthesis of Ni– benzene-1,3,5-tricarboxylic acid metal– organic framework 53 III.1.3 Ni@C, NiO@C synthesis 56 III Electrical system and single stack cell fabrication 56 III Quantitative characterizations .57 CHAPTER 4: RESULTS AND DISCUSSION 57 IV Urea sensor 57 iv IV 4.1 NiBTC materials .57 IV 4.1.1Morphological and structural studies .57 IV 4.1.2Electro-catalytic activity of Ni– benzene-1,3,5tricarboxylic acid metal–organic framework for urea electro-oxidation 65 IV 4.1.3Electrochemical performance of urea sensor 70 IV 4.1.4Interference, reproducibility and shelf life 75 IV 4.1.5Analysis of urea in urine sample 78 IV 4.2 LNF-CeO material .80 IV 4.2.1Structural and morphological characterization 80 IV 4.2.2Electrochemical analysis .82 IV 4.2.3Interference, stability, and real sample analysis 97 IV 4.3 Summary 100 IV Ni@C, NiO@C and NiBTC for direct urea fuel cell .104 IV 5.1 Characterization and optimization 104 IV 5.2 Catalytic performance of urea electro-oxidation on various forms of nickel supported-carbon 112 IV 5.3 Performances of DUFC 120 CHAPTER 5: SUMMARY AND CONCLUSIONS 133 CHAPTER 6: FUTURE WORK 135 APPENDICES 138 v REFERENCES 139 vi LIST OF FIGURES Figure 2-1 Comparison of energy density of different energy resources [89] 17 Figure 2-2 Schematic diagram of urea fuel cell system 19 Figure 2-3 Pictorial summary of major factors that contribute to fuel cell performance 27 Figure 2-4 The general model structure 31 Figure 2-5 Schematic of anode and cathode bonded to AEM in DUFC 32 Figure 3-1 The synthesis schematic of LNF-C material 52 Figure 3-2 Schematic diagram of Ni-BTC/MWCNT composite preparation and its application for electrochemical detection of urea 55 Figure 4-1 SEM images of (a) Ni-MOF-24 powder, (b) NiMOF particle, (c) composite of Ni-MOF/MWCNT, (d) STEM vii image of single Ni-MOF particle; and distribution of the nickel, carbon, and oxygen elements 59 Figure 4-2 SEM images (a) and particle-size distribution of Ni-MOF powder 60 Figure 4-3 Barrett-Joynet-Halenda (BJH) pore size distribution curves of Ni-MOF-24 60 Figure 4-4 (a) XRD patterns of MWCNT, Ni-MOF in 24h of hydrothermal reaction and Ni-MOF/MWCNT composite, (b) FT-IR spectra of H3BTC and Ni-MOFs, (c) XPS spectrum of Ni-MOF/MWCNT and (d) Ni 2p 63 Figure 4-5 Schematic representation of synthesis process of Ni-(BTC)MOF 63 Figure 4-6 Possible structure of Ni-(BTC)MOF 64 Figure 4-7 (a) Electrochemical response of Ni- BTC/MWCNT electrodes in a range concentration of 0-20 mM urea in 0.1M KOH solution, and (b) repetitive CV of the Ni-BTC/MWCNT/ITO non-enzymatic electrode in different viii ... thesis for the Degree of Doctor of Philosophy Nickel – based electro- oxidation catalysts for urea sensors and urea fuel cells By TRAN THAO QUYNH NGAN Submitted in Fulfillment of the Requirements for. .. Degree of Doctor of Philosophy July, 2018 Department of Chemical and biological engineering Graduate School Gachon University Thesis for Doctor of Philosophy? ??s Degree Nickel – based electro- oxidation. .. based electro- oxidation catalysts for urea sensors and urea fuel cells By TRAN THAO QUYNH NGAN Accepted in Fulfillment of the Requirements for the Degree of Doctor of Philosophy July 2018 Committee