Synthesis and functionalization of graphene as eletrode material for supercapacitors /
Teo, Ellie Yi Lih,
Synthesis and functionalization of graphene as eletrode material for supercapacitors / Ellie Teo Yi Lih - xxiii, 215 pages : illustrations (some color), chart ; 30 cm. + 1 CD-ROM
Faculty of Industrial Sciences and Technology
Thesis (Doctor of Philosophy in Advanced Materials) -- Universiti Malaysia Pahang – 2018
Includes bibliographical references
Supercapacitors, also known as ultracapacitors or electrochemical capacitors have attracted the attention of the research community over the past decade due to their attractive properties. It has been one of the focus of the research to search for a potential electrode material. Ever since its discovery, graphene have been in the limelight due to its intriguing properties. Graphene became an attractive electrode material which can also be combined with other materials such as the conducting polymer to be the used in energy storage devices like the supercapacitors. Various methods have been developed for the production of graphene. One of them is the chemical oxidation method where graphite is oxidized to form graphite oxide and subsequently reduced using reducing agent to obtain reduced graphene oxide (rGO). rGO however, suffers from agglomeration and poor solubility which are important issues that need to be addressed as they affect the electrochemical performance of rGO. Consequently, the main aim of this thesis is to prepare non-covalently modified reduced graphene oxide and reduced graphene oxide based material with enhanced electrochemical performance. rGO was non covalently modified with phenothiazine via hydrothermal treatment and mechanical mixing. Besides that, aminopyrene functionalized reduced graphene oxide (Ap-rGO) was also prepared via mechanical mixing and subsequently, Ap-rGO was polymerized with aniline to form aminopyrene functionalized reduced graphene oxide/polyaniline (Ap-rGO/PANI) composite. The materials were characterized with UV-vis spectroscopy, fourier transformed infrared spectroscopy (FTIR), fluorescence spectroscopy, x-ray photoelectron spectroscopy (XPS) and field emission scanning electron microscope/energy dispersive x-ray (FESEM/EDX). It was found that the non-covalent modifications have successfully occurred through π-π interactions. The electrochemical performances of the materials were investigated by cyclic voltammetry (CV), galvanostatic charge-discharge (CDC) and electrochemical impedance spectroscopy (EIS) in 1 M H2SO4 using the three-electrode system. Phenothiazine functionalized rGO obtained through hydrothermal method (PTZ[O]-rGO) and mechanical mixing (PTZ-rGO) exhibited specific capacitance of 277 F g-1 and 302 F g-1, which are 2.3 times and 2 times higher than their respective unfunctionalized analogues. Meanwhile, Ap-rGO exhibited high specific capacitance of 235 F g-1 and recorded capacitance retention of 92.7%. Upon polymerization with PANI to form Ap-rGO/PANI composite, the specific capacitance was further enhanced to 505 F g-1. Ap-rGO/PANI electrodes retained 87% of its capacitance after 4000 cycles, which shows that it has a higher stability as compared to PANI which exhibited stability of only 34.3%. To conclude, phenothiazine and aminopyrene both demonstrated the ability to form non-covalent interactions with rGO. The functionalized rGO electrodes exhibited superior electrochemical performance which makes it a promising electrode material for supercapacitors.
THE0007808(Local)
Faculty of Industrial Sciences and Technology--Dissertations
Universities and colleges--Disertations
Theses
Synthesis and functionalization of graphene as eletrode material for supercapacitors / Ellie Teo Yi Lih - xxiii, 215 pages : illustrations (some color), chart ; 30 cm. + 1 CD-ROM
Faculty of Industrial Sciences and Technology
Thesis (Doctor of Philosophy in Advanced Materials) -- Universiti Malaysia Pahang – 2018
Includes bibliographical references
Supercapacitors, also known as ultracapacitors or electrochemical capacitors have attracted the attention of the research community over the past decade due to their attractive properties. It has been one of the focus of the research to search for a potential electrode material. Ever since its discovery, graphene have been in the limelight due to its intriguing properties. Graphene became an attractive electrode material which can also be combined with other materials such as the conducting polymer to be the used in energy storage devices like the supercapacitors. Various methods have been developed for the production of graphene. One of them is the chemical oxidation method where graphite is oxidized to form graphite oxide and subsequently reduced using reducing agent to obtain reduced graphene oxide (rGO). rGO however, suffers from agglomeration and poor solubility which are important issues that need to be addressed as they affect the electrochemical performance of rGO. Consequently, the main aim of this thesis is to prepare non-covalently modified reduced graphene oxide and reduced graphene oxide based material with enhanced electrochemical performance. rGO was non covalently modified with phenothiazine via hydrothermal treatment and mechanical mixing. Besides that, aminopyrene functionalized reduced graphene oxide (Ap-rGO) was also prepared via mechanical mixing and subsequently, Ap-rGO was polymerized with aniline to form aminopyrene functionalized reduced graphene oxide/polyaniline (Ap-rGO/PANI) composite. The materials were characterized with UV-vis spectroscopy, fourier transformed infrared spectroscopy (FTIR), fluorescence spectroscopy, x-ray photoelectron spectroscopy (XPS) and field emission scanning electron microscope/energy dispersive x-ray (FESEM/EDX). It was found that the non-covalent modifications have successfully occurred through π-π interactions. The electrochemical performances of the materials were investigated by cyclic voltammetry (CV), galvanostatic charge-discharge (CDC) and electrochemical impedance spectroscopy (EIS) in 1 M H2SO4 using the three-electrode system. Phenothiazine functionalized rGO obtained through hydrothermal method (PTZ[O]-rGO) and mechanical mixing (PTZ-rGO) exhibited specific capacitance of 277 F g-1 and 302 F g-1, which are 2.3 times and 2 times higher than their respective unfunctionalized analogues. Meanwhile, Ap-rGO exhibited high specific capacitance of 235 F g-1 and recorded capacitance retention of 92.7%. Upon polymerization with PANI to form Ap-rGO/PANI composite, the specific capacitance was further enhanced to 505 F g-1. Ap-rGO/PANI electrodes retained 87% of its capacitance after 4000 cycles, which shows that it has a higher stability as compared to PANI which exhibited stability of only 34.3%. To conclude, phenothiazine and aminopyrene both demonstrated the ability to form non-covalent interactions with rGO. The functionalized rGO electrodes exhibited superior electrochemical performance which makes it a promising electrode material for supercapacitors.
THE0007808(Local)
Faculty of Industrial Sciences and Technology--Dissertations
Universities and colleges--Disertations
Theses