Master’s thesis Nanotechnology: Preparation of manganese dioxide/graphene composites by plasma enhanced electrochemical exfoliation process and its electrochemical performance

In this thesis, I have developed a low-cost, simple and one-step approach to synthesize MnO2/graphene composite with enhanced electrochemical performance. MnO2/graphene composite was prepared via a plasma-assisted electrochemical exfoliation method with an electrolyte solution made of KMnO4 precursor. | VIETNAM NATIONAL UNIVERSITY HANOI VIETNAM JAPAN UNIVERSITY NGUYEN THANH HAI PREPARATION OF MANGANESE DIOXIDE GRAPHENE COMPOSITES BY PLASMA-ENHANCED ELECTROCHEMICAL EXFOLIATION PROCESS AND ITS ELECTROCHEMICAL PERFORMANCE MASTER S THESIS Hanoi 2019 VIETNAM NATIONAL UNIVERSITY HANOI VIETNAM JAPAN UNIVERSITY NGUYEN THANH HAI PREPARATION OF MANGANESE DIOXIDE GRAPHENE COMPOSITES BY PLASMA-ENHANCED ELECTROCHEMICAL EXFOLIATION PROCESS AND ITS ELECTROCHEMICAL PERFORMANCE Major Nanotechnology Code Pilot Research supervisor Dr. Phan Ngoc Hong MASTER S THESIS Hanoi 2019 i TABLE OF CONTENTS TITLE PAGE .i TABLE OF CONTENTS . ii LIST OF FIGURES .iv LIST OF TABLES .vi LIST OF ABBREVIATIONS . vii ACKNOWLEDGMENTS . viii DECLARATION .ix ABSTRACT . x INTRODUCTION . 1 Chapter 1 OVERVIEW. 3 . Electrochemical energy storages . 3 . Supercapacitors . 5 . Electrode materials for supercapacitors . 6 . MnO2 graphene composites . 7 . Direct oxidation-reduction reaction . 8 . Solution-based mechanical mixing . 10 . The other methods . 13 . Current research in Vietnam . 15 Chapter 2 MATERIALS AND METHODS . 18 . Chemicals and reagents . 18 . Preparation of MnO2 graphene composites. 18 . Preparation of graphene and GM1 electrodes . 19 . Preparation of symmetric supercapacitor GM1 GM1 . 20 . Characterizations . 20 . Electrochemical analysis . 21 Chapter 3 RESULTS AND DISCUSSION . 23 . Characterizations of MnO2 graphene composites. 23 . The proposed mechanism for PE3P method . 29 . Electrochemical performance . 30 ii . Symmetric supercapacitor. 35 CONCLUSIONS . 39 LIST OF PUBLICATIONS . 40 REFERENCES. 42 iii LIST OF FIGURES Figure . A Ragone plot for various electrochemical energy storage devices 33 . . 4 Figure . The working principles of a electrochemical double layer capacitor carbon as the electrode material and b Pseudocapacitor MnO2 as the electrode material in Na2SO4 electrolyte 18 . . 5 Figure . a Schematic .