Now showing 1 - 10 of 26
  • Publication
    Effect of graphite dopant in polyvinylidene flouride (PVDF) electrospun composites
    ( 2024-12)
    Muhammad Zamzuri Mohd Saad
    ;
    ; ; ;
    Noorasikin Samat
    Polyvinylidene Fluoride (PVDF) is a high purity thermoplastic fluoropolymer that has huge potential, has been employed in numerous electronics, space, and aeronautics industries. The beta-phase of PVDF is the most beneficial due to its superior piezoelectric and pyroelectric properties, which are essential for high-performance applications. Thus, the research on attaining the beta-phase has been critical. PVDF crystallinity could be enhanced by varying processing methods and parameters, including electrospinning. Various researchers have reported on the electrospinning PVDF as a successful route to get beta-phase. The morphology, crystalline phases, and electrical conductivity of PVDF fiber are significantly influenced by electrospinning parameters. In this work, the effect of graphite loading in PVDF is one of the parameters examined. The objective of this work is to investigate the impact of graphite dopant loading on the electrical conductivity of electrospun PVDF composite. The most straightforward and affordable way to create PVDF fibers is by electrospinning. PVDF was first dissolved using N, N-Dimethylformamide (DMF) before mixing with graphite (0.25 wt%, 0.50 wt%, 0.75 wt%, and 1.0 wt%). Each solution was then electrospinned to produce conductive composite fiber. The parameters were fixed at 25 kV voltage; 1.5 ml/h flow rate; and 12 cm tip-to-collector distance. The morphology, electrical conductivity, and crystalline phases of electrospun PVDF fibers were examined using scanning electron microscope (SEM), four-point probe and X-ray diffraction (XRD) machine. As the graphite concentration rises, SEM micrograph showed that more beads were developed along with fiber sizes increment. Short electrospinning times result in insufficient electrospun mat thickness, which affects peak shift, according to XRD examination of all fibers. According to the results of the four-point probe examination, the conductivity rises dramatically and the resistance decreases as the graphite concentration increases.
  • Publication
    The hydrothermal synthesis of TiO₂-GO with enhance photocatalytic activity
    A composite material consisting of titanium dioxide and graphene oxide (TiO₂–GO) was synthesized through a hydrothermal reaction. This reaction involved the use of Ti(SO4)2 in an ethanol–water solvent. Different content of GO was studied to find the optimum parameter. The composites were subjected to characterization, encompassing an examination of their composition, structure, and microstructure through techniques such as X-ray diffraction (XRD), Raman spectra, scanning electron microscopy (SEM), and ultraviolet-visible diffuse reflectance spectroscopy. For Raman spectra, the presence of a G-band at approximately 1599 cm-1 and a D-band at 1350 cm-1 in the spectra indicates the presence of graphene oxide (GO). Therefore, the modified Hummer method synthesized graphite to GO. The findings for the XRD spectrum concerning the TiO2–GO composites revealed the presence of finely dispersed anatase TiO₂ particles on the surface of the graphene oxide sheet layer. Diffraction pattern similar to pristine TiO₂, only for TiO2–GO(0.75) and the peak for rutile TiO2 at 2Ɵ values 27.08° for both technique and TiO₂–GO(0.5) for spray technique. Apparently, GO sheets were almost covered by anchored TiO₂ particles, providing the possibility of efficient electronic conducting and electron transportation as in the SEM microstructures. EDS analysis shows the excessive carbon element for TiO₂-GO(0.75) and TiO₂-GO(1). The findings concerning the TiO₂–GO composites revealed the presence of finely dispersed anatase TiO₂ particles on the surface of the graphene oxide sheet layer. Notably, the photocatalytic performance of the TiO₂–GO composite significantly surpassed that of pure TiO₂ in the photodegradation of methyl blue (MB) when exposed to sunlight. The spray technique had a higher photocatalytic degradation percentage which is 82% for TiO₂-GO(0.25) compared to the dropped technique 79% which is TiO₂-GO(0.5). Degradation analysis of methyl blue concluded that the improved photocatalytic activity of TiO₂–GO primarily results from the enhanced efficiency in trapping and transporting electrons, which can be attributed to the presence of graphene oxide (GO).
  • Publication
    A controlled growth of carbon nanofibers (CNFs) on graphene
    ( 2023-12)
    Mishtha Fiyatillah
    ;
    ; ;
    L K Wisnu Kita
    ;
    ; ;
    A F Abd Rahim
    Carbon nanofibers (CNFs) have superior properties such as high conductivity, good mechanical strength, high specific surface area, and chemical stability. CNFs-graphene hybrid material can be used as a high-quality electrode in electronics applications. In the CNFs on graphene synthesis, the growth parameters must be well controlled. This work observes the evolution of the CNF's growth on graphene on Ni at reaction temperatures of 800oC and 860oC and at different reaction times of 30 min, 60 min, and 120 min. This research aims to find suitable conditions for obtaining controllable growth of CNFs on graphene. Based on the SEM measurement, it was found that the 860oC reaction temperature at 60 min and 120 min reaction time led to longer and smaller widths of CNFs with high coverage and distribution on graphene. The CNFs on graphene formation were confirmed by the XRD analysis.
  • Publication
    Phase Reduction and Thermodynamic Analysis of Ilmenite Ore by Carbothermal-Iodination using Different Carbon Reductants
    ( 2023-12-01)
    Nasrun N.A.
    ;
    ; ; ;
    Takahiro N.
    ;
    Rezan S.A.
    The present study is on the combination of carbothermal reduction and iodination reaction (carboiodination) process for the phase reduction of ilmenite ore (FeTiO3). The aim is to understand the phase reduction and thermodynamic reaction analysis of ilmenite ore by a combined method of carbothermal-iodination using different carbon reductants (graphite and palm char). Graphite was used as a standard carbon reductant while palm char as a renewable carbon reductant was prepared via the pyrolysis technique. Ilmenite was mixed with carbon reductants and then first reduced by using a carbothermal reduction process at 1550℃. Then, the reduced samples were further investigated with iodination reaction in different temperature ranges of 900-1000 °C using a vertical tube furnace with mixed argon and iodine gas (0.2 L/min). The proximate and ultimate analyses of carbon reductants were analysed by CHON analyser and their microstructure by using SEM, while XRF and XRD were used for analyzing the chemical compositions and the phase reductions of raw ilmenite ore and reduced samples, respectively. The thermodynamics of possible reactions during carbothermal-iodination reactions were calculated by HSC Chemistry 6.0 software. By comparing graphite and palm char, palm char had an amorphous structure, with porous and high carbon content showing high potential for usage as a reductant in titanium extraction from ilmenite ore. The phases of ilmenite ore were ilmenite, rutile, and anatase transformed into rutile, pseudobrookite, and titanium oxide detected by XRD. Further reduction was performed by palm char where more rutile (TiO2) and titanium oxide (Ti3O5) developed from the iodination reaction at the highest temperature compared to graphite due to better properties and amorphous structure. The rutile and titanium oxide were found as stable phases from the thermodynamic analysis and confirmed with XRD. From the findings, the combination of carbothermal-iodination of ilmenite ore was possible and promising for rutile (TiO2) production in mineral extractions.
      1
  • Publication
    A Review: Synthesis and Mechanism of Growth of the Carbon Nanotubes (CNTs) – Graphene Hybrid Material and its Application as Electrodes
    The CNTs–graphene hybrids have many advantages and potential for use in a wide range of electronic applications as electrodes. The CNTs–graphene hybrid structure outperforms the structure of each material in terms of characteristics and performance. There are several methods to grow CNTs. This paper reviews the chemical vapor deposition (CVD) method used to synthesize CNTs–graphene hybrid material. This paper discusses the processes and growth parameters of the synthesis of the CNTs-graphene hybrid. This paper also discusses the growth mechanism and kinetics of CNTs. In addition, the potential and performance of CNTs–Graphene hybrid material as electrodes in batteries are also reviewed.
      1
  • Publication
    Structural Characterizations and Phase Transition on the Reducibility of Ilmenite Ore with Different Carbon Reductants by Carbothermal Reduction Under Hydrogen Atmosphere
    ( 2023-12-01) ; ;
    Nasrun N.A.
    ;
    Kurniawan A.
    ;
    Nomura T.
    ;
    Rezan S.A.
    This research focused on investigating the properties and phase transition of ilmenite ore with various carbon reductants by performing a carbothermal reduction, followed by a hydrogen reduction (Ar:H2) at 900–1000 °C to extract rutile from the ore. To comprehend the impact of the carbon structure and characteristics on the reduction performance and incorporate a thermodynamic assessment during reduction reactions, two distinct carbon reductants: graphite (GI) and renewable carbon from palm char (PI), were selected. The phase transitions and reduced samples were examined using both qualitative and quantitative X-ray diffraction. The results revealed that ilmenite ore transformed into pseudobrookite ferrous (FeTi2O5), titanium trioxide (Ti3O5), rutile (TiO2), and iron (Fe) after carbothermal reduction at 1550 °C where brookite (TiO2) and anatase (TiO2) peaks were diminished. As the temperature rose during the secondary reduction by hydrogen, the reduction reaction sequenced as follows: FeTi2O5 → Ti3O5 → Ti2O3 → TiO2 and Fe. Due to the carbon structure and superior characteristics, the reduced PI demonstrated a greater degree of TiO2 reduction (81.8%) than the reduced GI (74.8%) at the highest reduction temperature of 1000 °C. In the early and middle stages of the reaction at high temperatures, the carbothermal reduction of ilmenite ore with solid carbon and CO participated and produced rutile, iron, and Ti3O5, whereas, in the latter stages, rutile, iron, and Ti2O3 are mostly formed when reduced by hydrogen. In conclusion, employing palm char with hydrogen atmosphere to extract pure rutile from ilmenite ore might be accomplished by using these proposed methods. Graphical Abstract: [Figure not available: see fulltext.]
      1
  • Publication
    Review on performance of lithium titanate and its impurities dopant as a lithium-ion battery anode
    Li-ion batteries are the main source of energy for electronic devices such as cameras, calculators, mobile phones, laptops, and electric vehicles. Among the materials being considered, lithium titanate (𝐿𝑖4𝑇𝑖5𝑂12) has become a promising anode material due to its high stability and safety, as well as enabling high operability without sacrificing lifetime. However, in order to further improve performance and customise properties for specific applications, impurity dopants have been investigated as a means of modifying 𝐿𝑖4𝑇𝑖5𝑂12 performance. This paper examines 𝐿𝑖4𝑇𝑖5𝑂12 and its impurities as anode materials. Starting with a basic understanding of the crystal structure and characteristics of 𝐿𝑖4𝑇𝑖5𝑂12, its properties and applications. Besides, this study explores the effects of different dopants on the 𝐿𝑖4𝑇𝑖5𝑂12 on battery parameters. Based on various research studies and recent developments, the review summarises the current knowledge about 𝐿𝑖4𝑇𝑖5𝑂12 and impurity dopants. Each dopant's different effects on the lattice structure highlight its importance for further development. As a result, it may lead to future research of 𝐿𝑖4𝑇𝑖5𝑂12 anodes for large-scale energy storage technology.
      45  3
  • Publication
    Preliminary Study of Hydrothermal Synthesis of TiO2-GO Composites as a High Performance Photocatalyst
    In this study, the addition of graphene oxide (GO) into TiO2 was investigated. GO was prepared by modified Hummer method before it was added into TiO2 via hydrothermal method. The graphite and GO was characterized by Raman spectra, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscope (SEM) along with the TiO2-GO composites also have been characterized. The morphology of TiO2 deposited on the surface of the GO sheet was observed by SEM. the phase formation of anisotropic anatase (TiO2) of the TiO2-GO was detected in XRD. The photocatalytic activity was determined by calculating the photodegradation efficiency of methylene blue (MB) under UV light irradiation. The photodegradation of MB were increased with time for TiO2-GO compared to pure TiO2. The results indicated that TiO2-GO composites was successfully produced using hydrothermal method for the photocatalytic application.
      18  2
  • Publication
    Physical, electrical and optical characterizations of Ba0.5Sr0.5TiO3 (BST) thin films
    ( 2020-01-08)
    Bakar Nurhanani Abu
    ;
    Adnan Johari
    ;
    ; ; ; ;
    Man Bahari
    Single layer Barium Strontium Titanate (BaxSr1-xTiO3) thin films were deposited on P type Silicon (Si) and thin Silicon Dioxide (SiO2) layer grown on Silicon (Si) substrate (1.5 cm x 1.5 cm) using spin coating technique were investigated in this work. The thin films were crystallized by annealing at 950 °C for 4 hours. Physical characterization was performed using XRD. Electrical and optical characterizations were aided by depositing Aluminum (Al) using Physical Vapor Deposition (PVD) on the thin films as electrode metal. I-V profile was obtained using Semiconductor Parametric Analyzer (SPA). A high impedance multimeter, light meter and a variable light source were introduced for optical characterizations including optical sensitivity, current density and I-V profile under variable light intensity from 0 to 900 Lux. Results show BST has diode like characteristics. The results which were compared with those from commercial solar cells and light sensors indicated that the BST thin films have potential as solar power generator and sensor.
      2  12
  • Publication
    Phase reduction and thermodynamic analysis of Ilmenite Ore by carbothermal-iodination using different carbon reductants
    ( 2023-12)
    N. A. Nasrun
    ;
    ; ; ;
    N. Takahiro
    ;
    S. A. Rezan
    The present study is on the combination of carbothermal reduction and iodination reaction (carboiodination) process for the phase reduction of ilmenite ore (FeTiO3). The aim is to understand the phase reduction and thermodynamic reaction analysis of ilmenite ore by a combined method of carbothermal-iodination using different carbon reductants (graphite and palm char). Graphite was used as a standard carbon reductant while palm char as a renewable carbon reductant was prepared via the pyrolysis technique. Ilmenite was mixed with carbon reductants and then first reduced by using a carbothermal reduction process at 1550℃. Then, the reduced samples were further investigated with iodination reaction in different temperature ranges of 900-1000 °C using a vertical tube furnace with mixed argon and iodine gas (0.2 L/min). The proximate and ultimate analyses of carbon reductants were analysed by CHON analyser and their microstructure by using SEM, while XRF and XRD were used for analyzing the chemical compositions and the phase reductions of raw ilmenite ore and reduced samples, respectively. The thermodynamics of possible reactions during carbothermal-iodination reactions were calculated by HSC Chemistry 6.0 software. By comparing graphite and palm char, palm char had an amorphous structure, with porous and high carbon content showing high potential for usage as a reductant in titanium extraction from ilmenite ore. The phases of ilmenite ore were ilmenite, rutile, and anatase transformed into rutile, pseudobrookite, and titanium oxide detected by XRD. Further reduction was performed by palm char where more rutile (TiO2) and titanium oxide (Ti3O5) developed from the iodination reaction at the highest temperature compared to graphite due to better properties and amorphous structure. The rutile and titanium oxide were found as stable phases from the thermodynamic analysis and confirmed with XRD. From the findings, the combination of carbothermal-iodination of ilmenite ore was possible and promising for rutile (TiO2) production in mineral extractions.
      13  2