Browsing by Author "Nor, Najah Syahirah Mohd"

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    Effects of Activation Time on the Performance of Supercapacitor Binderless Activated Carbon Electrodes Derived from Fibers of Oil Palm Empty Fruit Bunches
    (2015-09-07) Ishak; Deraman, Mohamad; Dollah, Besek Nurdiana Mohd; Othman; Omar, Ramli; Basri, Nur Hamizah; Nor, Najah Syahirah Mohd; Taer, Erman; Awitdrus; Farma, Rakhmawati; Aziz
    Green monoliths (GMs) with different composition, labelled as GM1, GM2 and GM3, were prepared from self-adhesive carbon grains (SACG) produced from fibers of oil palm empty fruit bunches, SACG treated with 0.4 M H2SO4 and mixtures of SACG and carbon nanotubes (5 wt.%) treated with 0.4 M H2SO4, respectively. Each GMs was carbonized and then activated with holding time of 1 h and 2 h, respectively, to produce their respective activated carbon monoliths (ACMs). These ACMs were used as electrodes to fabricate supercapacitor cells using H2SO4 electrolytes, Teflon separator and stainless steel 316L current collector. The porosity of the ACMs, examined by nitrogen adsorption-desorption isotherm method were found affected after prolonging the activation time. From the electrochemical characterization of the ACMs electrodes using galvanic charge-discharge methods, it was found that supercapacitor cells fabricated using the ACMs produced by longer activation time (2 h) showed better performance, which had higher specific capacitance (113 F/g), specific power (159 W/kg) and specific energy (3.35 W h/kg), compared to the cells using ACMs produced by shorter activation time (1 h).
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    Influence of gamma irradiation exposure on the performance of supercapacitor electrodes made from oil palm empty fruit bunches
    (2015-08-18) Nor, Najah Syahirah Mohd; Deraman, Mohamad; Omar, Ramli; Awitdrus; Farma, Rakhmawati; Basri, Nur Hamizah; Dolah, Besek Nurdiana Mohd; Mamat, Nurul Fatin; Yatim, Baharudin; Daud, Mohd Norizam Md
    Carbon-monolith electrodes for supercapacitors were prepared from GMs (green monoliths) made from pre-carbonized fibers of oil palm EFB (empty fruit bunches) and GMs of pre-carbonized EFB fibers exposed to gamma radiation at 5 kGy, 15 kGy, and 20 kGy. GMs and irradiated GMs were carbonized and activated to prepare ACM (activated-carbon-monolith) electrodes. The gamma radiation affected the pore structure of the ACM electrodes and the electrochemical performance of the supercapacitors; irradiation doses of 0 kGy, 5 kGy, 15 kGy and 20 kGy produced specific capacitances of 121 F g 1, 196 F g 1, 11 F g 1, and 12 F g 1, respectively. The irradiation dose of 5 kGy appears to be optimum and produces a specific power and specific energy of 236 W kg 1 and 5.45 W h kg 1, respectively, representing 34% and 60% increases over ACM electrodes prepared from non-irradiated GMs.
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    Nanoporous separators for supercapacitor using activated carbon monolith electrode from oil palm empty fruit bunches
    (2015-09-06) Nor, Najah Syahirah Mohd; Deraman, Mohamad; Omar, Ramli; Taer, Erman; Awitdrus; Farma, Rakhmawati; Basri, Nur Hamizah
    Activated porous carbon electrode prepared from fibres of oil palm empty fruit bunches was used for preparing the carbon based supercapacitor cells. The symmetrical supercapacitor cells were fabricated using carbon electrodes, stainless steel current collector, H2SO4 electrolyte, and three types of nanoporous separators. Cells A, B and C were fabricated using polypropylene, eggshell membrane, and filter paper, respectively. Electrochemical characterizations data from Electrochemical Impedance Spectroscopy, Cyclic Voltammetry, and Galvanic Charge Discharge techniques showed that specific capacitance, specific power and specific energy for cell A were 122 F g-1, 177 W kg-1, 3.42 Wh kg-1, cell B; 125 F g- 1, 179 W kg-1, and 3.64 Wh kg-1, and cell C; 180 F g-1, 178 W kg-1, 4.27 Wh kg-1. All the micrographs from Field Emission Scanning Electron Microscope showed that the different in nanoporous structure of the separators lead to a significant different in influencing the values of specific capacitance, power and energy of supercapacitors, which is associated with the mobility of ion into the pore network. These results indicated that the filter paper was superior than the eggshell membrane and polypropylene nanoporous separators. However, we found that in terms of acidic resistance, polypropylene was the best nanoporous separator for acidic medium.
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    A New Empirical Equation for Estimating Specific Surface Area of Supercapacitor Carbon Electrode from X-ray Diffraction
    (2015-08-18) Deraman, Mohamad; Daik, Rusli; Soltaninejad, Sepideh; Nor, Najah Syahirah Mohd; Awitdrus; Farma, Rakhmawati; Mamat, Nurul Fatin; Basri, Nur Hamizah; Othman, Mohd Amir Radhi
    The current trend of increasing research interest in supercapacitor is due to high demands for an energy storage device that can work in systems that require either low or high power-energy usage. In a supercapacitor using porous carbon electrodes, the energy storage mechanism involves the electrolyte ions in electrode pores and electronic charges in electrodes to form electric double layers at the electrode-electrolyte interface without undergoes any chemical reaction. The specific surface area of porous electrodes, which affect the performance of supercapacitor, have been widely investigated by many researchers using the nitrogen adsorption-desorption measurement. However, despite its simplicity, the X-ray diffraction method is rarely found being used to determine the specific surface area of porous electrodes. Therefore, in the present paper, we propose a new equation which expressed the specific surface area of electrodes as a function the electrode structural parameters obtained from the X-ray diffraction data, and duration of activation time employed during the electrode preparation. This equation is found to produce a satisfactory result and is expected to be beneficial for studying supercapacitor electrode materials
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    Physical and electrochemical properties of supercapacitor composite electrodes prepared from biomass carbon and carbon from green petroleum coke
    (2015-09-09) Awitdrus; Deraman, Mohamad; Talib; Farma, Rakhmawati; Omar, Ramli; Ishak; Taer, Erman; Dollah, Besek Nurdiana Mohd; Basri, Nur Hamizah; Nor, Najah Syahirah Mohd
    The green monoliths (GMs) were prepared from the mixtures of pre-carbonized fibers of oil palm empty fruit bunches (or self-adhesive carbon grains (SACG)) and green petroleum coke (GPC) with the mixing ratio of 0, 10, 30, 50 and 70 % GPC, respectively. The GMs were carbonized in N2 environment at 800oC to produce carbon monoliths (CM00, CM10, CM30, CM50 and CM70). The CMs were CO2 activated at 800oC for 1 hour to produced activated carbon monolith electrodes (ACM00, ACM10, ACM30, ACM50 and ACM70). For each percentage of GPC, three duplicate symmetrical supercapacitor cells were fabricated using these activated carbon monolith electrodes respectively, and the capacitive performance amongst the cells was compared and analyzed in order to observe the relationship between the capacitive performance and the physical properties (microstructure and porosity) of the ACMs electrodes containing varying percentage of GPC.