The Electrochemical Performance of Deposited Manganese Oxide-Based Film as Electrode Material for Electrochemical Capacitor Application

The transition metal oxide has been recognized as one of the promising electrode materials for electrochemical capacitor application. Due to the participation of charge transfer reactions, the capacitance offered by transition metal oxide can be higher compared to double layer capacitance. The investigation on hydrous ruthenium oxide has revealed the surface redox reactions that contributed to the wide potential window shown on cyclic voltammetry curve. Although the performance of ruthenium oxide is impressive, its toxicity has limited itself from commercial application. Manganese oxide is a pseudocapacitive material behaves similar to ruthenium oxide. It consists of various oxidation states which allow the occurrence of redox reactions. It is also environmental friendly, low cost, and natural abundant. The charge storage of manganese oxide film takes into account of the redox reactions between Mn3+ and Mn4+ and can be accounted to two mechanisms. The first one involves the intercalation/deintercalation of electrolyte ions and/or protons upon reduction/oxidation processes. The second contributor for the charge storage is due to the surface adsorption of electrolyte ions on the electrode surface

Effect of calcination temperature and time on waste heterogeneous catalysts for biodiesel production

This paper studies the effect of calcination time and temperature of mixed waste catalyst for optimization of FAME yield. Fish bone and mixture of coconut waste and eggshells were used to catalyzed the transesterification process. The parameter was tested on different calcination condition and the result shows that the optimum condition was achieved at condition 800˚C, 2 hours was 80.3 wt% of FAME yield for mixed coconut waste and eggshells and 85 wt% were obtained at 900˚C for fish bone catalyst at 225 rpm, 12:1 methanol to oil ratio and amount of catalyst, 3wt%. It can be concluded that waste heterogeneous catalyst exhibits as a cheaper substitute to the homogenous catalyst

Penilaian pretasi pelajar MDAB yang mengikuti program diploma Pengurusan dan teknologi pejabat, UiTM Pahang / Siti Khalijah Majid & Rohana Rohana Johan

Kajian ini melihat kepada perkembangan prestasi pelajar-pelajar MDAB atau yang mengikuti program Pra Perdagangan di UiTM sebelum mengikuti program Diploma Pengurusan dan Teknologi Pejabat. Seramai 106 orang pelajar tahun akhir sesi Mac – Julai 2018 telah dijadikan responden kepada kajian kes ini. Seramai 74 orang dari bilangan tersebut adalah pelajar MDAB dan hanya 32 orang adalah pelajar yang memasuki UiTM dengan keputusan lepasan SPM. Perbandingan dibuat di antara kedua kumpulan ini dan hasil kajian mendapati bahawa bilangan pelajar yang tamat di dalam tempoh adalah 67.2% bagi pelajar MDAB dan 100% dari kumpulan lepasan SPM. Manakala bilangan yang menyambung pengajian adalah 32.8% bagi pelajar MDAB. Kursus yang paling mencabar bagi kedua-dua kumpulan ini ialah kursus ACC106 bagi pelajar lepasan SPM (49%) dan OBM345 bagi pelajar MDAB (33%). Terdapat 17.9% pelajar MDAB yang berjaya menamatkan pengajian dengan sijil dekan sementara pelajar lepasan SPM yang tamat dengan sijil dekan ialah seramai 31.25%. Bagi pelajar ANC pula, terdapat tiga (3) orang pelajar di dalam kalangan pelajar lepasan SPM yang mendapat ANC manakala hanya seorang sahaja dari kalangan pelajar MDAB yang berjaya memperolehi anugerah tersebut. Namum begitu pelajar MDAB yang tamat dengan HPNG 3.00 ke atas adalah seramai 53.8% dan 87.5% bagi pelajar lepasan SPM. Kesimpulannya, peluang yang diberikan oleh UiTM kepada pelajar pra atau MDAB perlu digunakan sebaik mungkin kerana peluang untuk berjaya mendapatkan diploma dan memperbaiki diri sendiri dan keluarga boleh direalisasikan dengan berkat kesungguhan dan usaha dari semua pihak sama ada pelajar, pensyarah mahupun institusi itu sendiri

Characterisation of plasticised PVDF–HFP polymer electrolytes

This study focuses on the preparation and characterisation of sodium ion conducting polymer electrolytes. Poly(vinylidenefluoride-co-hexafluoropropylene) has been used as the host matrix and hydrated sodium sulphide (Na2S.9H2O) salt as the source of charge carriers in the polymer electrolyte system. To the highest conducting polymer–salt electrolyte, different concentrations of equal weight of propylene carbonate and diethyl carbonate mixture have been added, and the electrolytes have been characterised by X-ray diffraction, Fourier transform infrared spectrometry, scanning electron microscopy and electrochemical impedance spectroscopy. The room temperature ionic conductivity of 1?3461024 S cm21 for the unplasticised electrolyte with a composition of 65 wt-% poly(vinylidenefluoride-co-hexafluoropropylene)–35 wt-%Na2S increased to 3?4961024 S cm21 when 30 wt-% propylene carbonate/diethyl carbonate (w/w51) plasticisers were added

Graphene oxide and its electrochemical performance

In this study, graphene oxide (GO) was synthesized from graphite flakes using simplified Hummer’s method. Field Emission Scanning Electron Microscopy (FESEM) image showed that the GO nanosheets had an average area 7000 μm2 with lateral dimension of up to 150 μm. The X-Ray Diffraction (XRD) pattern revealed a (002) diffraction peak, signifying the successful synthesis of GO. GO solution was cast on an aluminum (Al) foil placed in a petri dish and left to dry to form an electrode made up of GO film on the Al foil (GO-Al). It was found that GO-Al exhibited equivalent series resistance (ESR) close to that of the Al foil

Input range driver for measurement of a differential 10 bit SAR ADC

Imbalance and out-of-range input signals can cause inaccuracy in fully differential successive approximation (SAR) analog to digital converter (ADC). Therefore, implementation of an ADC driver can solve the problem since the input can be properly adjusted to suit with an ADC input. AD8139 single to differential amplifier was chosen as an ADC driver in this design and placed on a printed circuit board (PCB) to drive differential input signal of SAR ADC. The result shows each of output amplitude of the amplifier remains equal and is 180° out of phase for DC and AC input signal. The fabricated 10 bit SAR ADC is capable to digitize full code from analog input produced by the ADC driver

Manganese oxide-based nanocomposite electrodes for supercapacitors / Siti Rohana Majid

The increasing demands on energy have led to environmental issues and the depletion of fossil fuels. The intense research on energy storage and conversion has attracted much attention for future technology development. Batteries have become a choice for energy storage devices in many applications. However, expanding markets are pushing for alternative pulse batteries that offer high power and long cycle life. Inspired by this, supercapacitors have attracted growing interest due to their high power density, long cycle life, and fast charging rate, which display great potential in complimenting or even replacing batteries in many applications. The research work in this project concentrates on improving the specific capacitance or energy density of nanostructure composite metal oxides electrodes, namely oxides of manganese, nickel and cobalt (MnO2, MnO2/NiO and Mn3O4/NiO/Co3O4) with porous texture morphology. First, MnO2 was deposited on top of stainless steel by simple chronopotentiometry electrodeposition method with various manganese acetate tetrahydrate (Mn(CH3COO)2·4H2O) concentrations in deposition solution. The optimum performance was obtained using 0.01 M Mn(CH3COO)2·4H2O. In order to enhance the specific capacitance of MnO2 electrode, the NiO was incorporated into the MnO2 electrode by adding different concentrations of nickel acetate tetrahydrate (Ni(CH3COO)2·4H2O) mixed with 0.01 M Mn(CH3COO)2·4H2O. The optimum performance of MnO2-NiO electrode was obtained using the deposition solution containing 0.25 M Ni(CH3COO)2·4H2O mixed with 0.01 M Mn(CH3COO)2·4H2O. The optimum MnO2-NiO electrode was further studied in different electrodeposition modes and different CV’s cycles. The work proceeded by adding different concentrations of cobalt ion into 0.01 M Mn(CH3COO)2·4H2O mixed with 0.25 M Ni(CH3COO)2·4H2O concentration. The iv effect of the addition of different cobalt ion concentrations was explored and the obtained Mn3O4-NiO-Co3O4 ternary electrode exhibited optimum specific capacitance of 7404 F g-1 with high energy and power density of 1028 Wh kg-1 and 99 kW kg-1 respectively at current density of 20 A g-1 in 0.5 M potassium hydroxide (KOH)/0.04 M potassium ferrocyanide (K3Fe(CN)6) mixture electrolyte. Lastly, the electrochemical performance of supercapacitors were enhanced by incorporating MnO2 electrode with carbon based composite (reduce graphene oxide (RGO)/glucose carbon). The incorporation of RGO/glucose carbon into MnO2 electrode increased the electrical conductivity of the electrode. The introduction of D (+) glucose into the deposition solution slowed down the nucleation process of MnO2 particles and led to uniform and ultrathin nanoflakes structure. The optimized electrode exhibited low transfer resistance and resulted in excellent electrochemical performance in three electrolyte systems viz. sodium sulfate (Na2SO4), KOH and KOH/K3Fe(CN)6 electrolytes. The optimum specific capacitance obtained was 13,333 F g-1 with energy density and power density of 1851 Wh kg-1 and 68 kW kg-1 respectively at current density of 20 A g-1 in mixed 0.5 M KOH/0.04 M K3Fe(CN)6 electrolyte. The preparation of electrodes in this work using electrodeposition method is simple, low-cost, and environmental-friendly. It holds great potential to produce cost-effective and high energy density supercapacitors

Electrochemical performance of binder-free NiO-PANI on etched carbon cloth as active electrode material for supercapacitor

Binder free electrode for supercapacitor application was successfully fabricated which consists of carbon cloth‑nickel oxide-polyaniline (EC-NiP). The composite electrode was prepared by growing NiO on EC via hydrothermal followed by the electrodeposition of PANI. The crystallite sizes of NiO were varied from 5.73 nm to 17.81 nm over the temperature range of 200 to 500 °C. The optimized electrode, heated at 300 °C (NIP300) showed good specific capacitance of 192.31 Fg−1 with energy density of 21.63 mWhkg−1 and 4.81 Wkg−1 of power density at 0.5 Ag−1 current density in 0.5 M H2SO4 electrolyte. The symmetrical NIP300//PVA + 0.5 M H2SO4//NIP300 cell exhibit excellent reversibility where the specific capacitance retained 72% of the initial value after 4500 cycles

Mobility and density of ions in chitosan-orthophosphoric acid-ammonium nitrate electrolytes

An important factor that contributes significantly to the conductivity of a material is the number density and mobility of the mobile species. In this work the number density of mobile ions, n, was calculated using the Rice and Roth model and the random walk formulation. The value of n as calculated using the Rice and Roth model depends on the activation energy and mean free path of the ions whereas calculation using the random walk formulation depends on the hopping rates of the ions. Our results show that the values of n calculated using the random walk formulation is more than one order of magnitude larger than that calculated using the Rice and Roth model. Unlike mobility, the values of n do not show significant changes with temperature. This suggests that mobility influences the conductivity of the polymer at elevated temperatures. (c) 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinbeim

Electrical behavior of proton-conducting chitosan-phosphoric acid-based electrolytes

Dielectric and AC conductivity studies have been carried out for chitosan-based proton-conducting electrolytes. Chitosan-phosphoric acid (CP) and chitosan composite (CPS) electrolytes were prepared using the solution cast method. In both systems, the frequency dependence of epsilon(r), M-i and tan delta is non-Debye type. The AC conductivity in both electrolytes follows the Jonscher power law. Conduction mechanism studies show that the CP sample follows the quantum mechanical tunneling (QMT) model and the CPS electrolyte follows the overlapping large polaron-tunneling (OLPT) model. (c) 2006 Elsevier BN. All rights reserved