Hydrogen Storage in Ni/graphene and Pd/graphene Nanomaterials

169 Pages·2017·28.99 MB·English

Hydrogen Storage in Ni/graphene and Pd/graphene Nanomaterials

A Thesis Submitted to the College of Graduate and Postdoctoral Studies
In Partial Fulfillment of the Requirements
For the Degree of Doctor of Philosophy
In the Department of Mechanical Engineering
University of Saskatchewan

By
Chunyu Zhou

© Copyright Chunyu Zhou, December, 2016 All Rights Reserved.
PERMISSION TO USE
In presenting this thesis in partial fulfillment of the requirements for a postgraduate degree from
the University of Saskatchewan, I agree that the Libraries of this University may make it freely
available for inspection. I further agree that permission for copying of this thesis in any manner,
in whole or in part, for scholarly purposes may be granted by the Dr. J. A. Szpunar who
supervised my thesis work or, in their absence, by the Head of the Department or the Dean of the
College in which my thesis work was done. It is understood that any copying or publication or
use of this thesis or parts thereof for financial gain shall not be allowed without my written
permission. It is also understood that due recognition shall be given to me and to the University
of Saskatchewan in any scholarly use which may be made of any material in my thesis.
Requests for permission to copy or to make other use of material in this thesis in whole or part
should be addressed to:

Head of the Department of Mechanical Engineering
57 Campus Dr.
University of Saskatchewan
Saskatoon, Saskatchewan (S7N 5A9)

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ABSTRACT
Hydrogen is a promising energy carrier that could be an alternative to the traditional carbon
based fuels. Hydrogen storage in the Ni/graphene and Pd/graphene systems was investigated in
the present work using Thermogravimetric Analysis (TGA).
A laboratory apparatus was designed, built and applied for hydrogenation under pressure. Novel
synthesis methods were developed to synthesize the graphene-based composites. Multiple
characterizations have been performed to understand the sorbent structures, including the
component determination and distribution, chemical state, electronic structure and metal-
graphene interfaces. The hydrogen storage behavior was determined, and a hypothesis was
proposed to explain the hydrogen performance in the sorbents.
The Ni/graphene (5 at.% Ni, atomic percentage; 100 at.% : Ni + C) composite, charged with H
2
pressure under 1 and 60 bar desorbed 0.14 wt.% H and 1.18 wt.%, respectively, in a TGA
2
apparatus under a flow of argon, at room temperature. The hydrogen release could occur at an
operating temperature below 150°C and was completed at 250°C.
The Pd/graphene (1 at.% Pd, 100 at.% : Pd + C) composite, charged under H pressure of 50 and
2
60 bar released 6.7 and 8.67 wt.% H , respectively, in a TGA apparatus under a flow of argon, at
2
room temperature. The 5%Pd/graphene (5 at.% Pd, 100 at.% : Pd + C) composite charged under
60 bar H and dehydrogenated under the same conditions in a TGA apparatus, released 7.16 wt.%
2
H . The composites could discharge hydrogen below 100°C and complete the process up to
2
200°C. The Pd/graphene system releases relatively high hydrogen storage capacity in TGA.
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ACKNOWLEDGEMENTS
I would like to express my sincere gratitude to my supervisor, Dr. Jerzy A. Szpunar for being a
wonderful mentor, for all his continuous guidance, enthusiasm, support, inspiration and patience
throughout the research. Besides, his passion and curiosity for life, energetic attitude also
motivate me towards a positive lifestyle.
I greatly acknowledge the advisory committee members: Dr. Hui Wang, Dr. Yongfeng Hu, Dr.
Ikechukwuka Oguocha and Dr. Szyszkowski Walerian for the constructive comments. I thank
external examiner, Prof. Robert Varin, for his insightful points.
My great thanks go to Mr. Fan Fan and Mr. Xu Wang for the experimental discussions and
operations, and for offering kind assistance whenever they could. My special thanks go to Mr.
Siyamak Javadian for his kind advice in scientific attitude and methods at my starting phase of
project. I also appreciate the beamline scientists Dr. Jian Wang and Dr. Xiaoyu Cui for their kind
comments on my research and help with the data collections.
I would like to thank the staff and students from various departments for their friendly, effective
assistance and support. The list goes to Mr. Blair, Mr. Dung, Ms. Helen Yin, Mr. Rob Peace, Dr.
Daniel Chen, Dr. Ajay Rajaram, Ms. Heli Eunike, Mr. Richard Blondin, Mr. Qunfeng Xiao, Mr.
Guosheng Liu and Mr. Bei Yan.
I thank Mr. Tedric Soh, Dr. Nilesh Gurao, Dr. Razavi Tousi, Seyed Salman, Ravikiran
Siripurapu and other colleagues in the Advance Materials and Renewable Energy (AMRE)
research team.
I acknowledge the Natural Sciences and Engineering Research Council of Canada (NSERC), and
particularly express my gratitude to the China Scholarship Council (CSC) for the continuous
financial support.
Last but by no means least, my special thanks go to my family: especially my husband and also
my best friend Ming Zhu for being with me with great love, ongoing support and understanding;
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my dear father for his continuous support and strong spiritual backing. Without their support, it
would have been much more difficult to complete a Ph.D. degree.
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DEDICATION
This thesis is dedicated to my thoughtful husband and beloved parents for their unconditional
love and ongoing support in my life.
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TABLE OF CONTENTS

PERMISSION TO USE ................................................................................................................. i
ABSTRACT .................................................................................................................................. ii
ACKNOWLEDGEMENTS ........................................................................................................ iii
DEDICATION ............................................................................................................................... v
TABLE OF CONTENTS ............................................................................................................. vi
LIST OF TABLES ......................................................................................................................... x
LIST OF FIGURES ...................................................................................................................... xi
ACRONYMS ................................................................................................................................ xv
1 INTRODUCTION ............................................................................................................. 1
1.1 Overview ........................................................................................................................... 1
1.2 Research objectives ........................................................................................................... 3
1.3 Thesis outline .................................................................................................................... 3
2 LITUREATURE REVIEW .............................................................................................. 5
2.1 Hydrogen storage .............................................................................................................. 5
2.1.1 Technological barriers ............................................................................................... 5
2.1.2 Storage technology .................................................................................................... 6
2.1.3 Storage materials ....................................................................................................... 8
2.2 Graphene ........................................................................................................................... 9
2.2.1 Graphene nanomaterials ............................................................................................ 9
2.2.2 Preparation ............................................................................................................... 12
2.2.3 Properties and applications ...................................................................................... 12
2.3 Hydrogen storage in metal/graphene .............................................................................. 13
2.3.1 Methods for hydrogen storage ................................................................................. 13
2.3.2 Theoretical and experimental findings .................................................................... 15
2.3.3 Metal-graphene interface ......................................................................................... 16
2.3.4 Mechanism of hydrogen storage ............................................................................. 17
2.4 Summary ......................................................................................................................... 19
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3 METHODOLOGY .......................................................................................................... 20
3.1 Apparatus for hydrogen charging ................................................................................... 22
3.2 Preparation ...................................................................................................................... 23
3.2.1 Preparation of graphene ........................................................................................... 23
3.2.2 Synthesis of Ni/graphene composite ....................................................................... 26
3.2.3 Synthesis of Pd/graphene composite ....................................................................... 29
3.3 Characterization techniques ............................................................................................ 31
3.3.1 XRD analysis of crystal structure ............................................................................ 31
3.3.2 BET analysis of surface area, pore size and porosity .............................................. 31
3.3.3 Microscopy analysis of morphology ....................................................................... 31
3.3.4 Spectroscopy analysis of chemical and electronic structure ................................... 32
3.3.5 TGA test of weight change ...................................................................................... 34
3.4 Summary ......................................................................................................................... 35
4 NI/GRAPHENE NANOCOMPOSITE .......................................................................... 36
4.1 Abstract ........................................................................................................................... 39
4.2 Introduction ..................................................................................................................... 39
4.3 Experimental procedures ................................................................................................ 40
4.3.1 Synthesis of Ni/graphene nanocomposite ............................................................... 40
4.3.2 Characterization techniques ..................................................................................... 40
4.3.3 Hydrogen charge and discharge .............................................................................. 41
4.4 Results and discussion .................................................................................................... 42
4.4.1 Phase composition and morphology ........................................................................ 42
4.4.2 Electronic structure .................................................................................................. 48
4.4.3 Hydrogen release measurement ............................................................................... 51
4.4.4 Hydrogen release mechanism .................................................................................. 55
4.4.5 Violation of the Van’t Hoff Law in TGA ................................................................ 57
4.5 Conclusions ..................................................................................................................... 58
5 X-RAY CHEMICAL IMAGING AND ELECTRONIC STRUCTURE OF A
SINGLE NANOPLATELET NI/GRAPHENE COMPOSITE ................................... 59
5.1 Abstract ........................................................................................................................... 61
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5.2 Introduction ..................................................................................................................... 61
5.3 Experimental section ....................................................................................................... 63
5.4 Results and discussion .................................................................................................... 63
5.4.1 Ni-graphene interface analysis ................................................................................ 63
5.4.2 Schematic configuration of Ni-graphene interface .................................................. 69
5.5 Conclusions ..................................................................................................................... 71
6 PD/GRAPHENE NANOCOMPOSITES ....................................................................... 72
6.1 Abstract ........................................................................................................................... 76
6.2 Introduction ..................................................................................................................... 76
6.3 Experimental section ....................................................................................................... 77
6.3.1 Preparation of graphene gel ..................................................................................... 77
6.3.2 Synthesis of Pd/graphene composite ....................................................................... 77
6.3.3 Material characterization ......................................................................................... 77
6.3.4 Hydrogen release measurement ............................................................................... 78
6.4 Results and discussion .................................................................................................... 79
6.4.1 Decoration of graphene ........................................................................................... 79
6.4.2 Morphology and structure ....................................................................................... 80
6.4.3 Hydrogen release ..................................................................................................... 83
6.4.4 Electronic structure analysis .................................................................................... 88
6.4.5 Hydrogen release mechanism .................................................................................. 91
6.5 Conclusions ..................................................................................................................... 93
7 CONCLUSIONS AND FUTURE RESEARCH ........................................................... 94
7.1 Summary ......................................................................................................................... 94
7.2 Conclusions ..................................................................................................................... 96
7.3 Contribution to original knowledge ................................................................................ 96
7.4 Limitations of the hydrogen storage measurements ....................................................... 97
7.5 Sieverts technique ........................................................................................................... 98
7.6 Suggestions for future work ............................................................................................ 99
REFERENCES .......................................................................................................................... 101
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APPENDIX A. CUSTOM-MADE APPARATUS FOR HYDROGEN STORAGE
DETERMINATION. ................................................................................................................. 121
APPENDIX B. SUPPORTING INFORMATION .................................................................. 129
Supporting Information of Chapter 4 .................................................................................. 129
Supporting Information of Chapter 5 .................................................................................. 132
Supporting Information of Chapter 6 .................................................................................. 140
APPENDIX C. COPYRIGHT PERMISSION ........................................................................ 149
Copyright Permission for manuscript 1 and 3 (Chapter 4 and Chapter 6) .......................... 149
Copyright Permission for manuscript 2 (Chapter 5) ........................................................... 152

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