Now showing 1 - 5 of 5
  • Publication
    The effect of polyethylene glycol addition on wettability and optical properties of GO/TiO2 thin film
    Modification has been made to TiO2 thin film to improve the wettability and the absorption of light. The sol-gel spin coating method was successfully used to synthesize GO/TiO2 thin films using a titanium (IV) isopropoxide (TTIP) as a precursor. Different amounts of polyethylene glycol (PEG) (20 to 100 mg) were added into the parent sol solution to improve the optical properties and wettability of the GO/TiO2 thin film. The effect of different amounts of PEG was characterized using X-ray diffraction (XRD) for the phase composition, scanning electron microscopy (SEM) for microstructure observation, atomic force microscopy (AFM) for the surface topography, ultraviolet–visible spectrophotometry (UV-VIS) for the optical properties and wettability of the thin films by measuring the water contact angle. The XRD analysis showed the amorphous phase. The SEM and AFM images revealed that the particles were less agglomerated and surface roughness increases from 1.21 × 102 to 2.63 × 102 nm when the amount of PEG increased. The wettability analysis results show that the water contact angle of the thin film decreased to 27.52° with the increase of PEG to 80 mg which indicated that the thin film has hydrophilic properties. The optical properties also improved significantly, where the light absorbance wavelength became wider and the band gap was reduced from 3.31 to 2.82 eV with the presence of PEG.
      1  2
  • Publication
    The Effect of GO/TiO2 Thin Film During Photodegradation of Methylene Blue Dye
    Titanium (IV) isopropoxide (TTIP) was used to synthesize GO/TiO2 thin films using a sol-gel spin-coating method onto a glass substrate, undergoing an heat tretment at 350 °C. Several amounts of graphene oxide (GO) (0-20mg) were weighed into a sol solution of TiO2 to produce GO/TiO2 thin films. The thin film samples were characterized by X-ray diffraction (XRD) to analyze the samples’ phase and by scanning electron microscopy (SEM) to analyze the samples’ microstructure. Physical testing such as water contact angle (WCA) was analyzed using an optical microscope with J-Image software. In contrast, the optical band gap and photodegradation of methylene blue under sunlight irradiation of the thin film was analyzed using UV-VIS spectrophotometry. GO5 thin film sample showed low-intensity anatase phase formation, where the microstructure revealed a larger surface area with the addition of GO. WCA reveals that GO/TiO2 thin film exhibits super hydrophilic properties where the angle decreases from 37.83° to 4.11°. The optical result shows that GO has improved the absorption edges by expanding into visible regions. Moreover, due to the existence of GO 3.30 eV band gap energy of TiO2 decreases from to 3.18 eV obtained by GO5. The improved adsorption edge allows Ti3+, O2 and interstitial states to be formed in low valence states with energy underneath than in the TiO2 band gap. Therefore, the photodegradation of methylene blue (MB) dye increases from 48 % to 59 % in the GO/TiO2 thin film.
      34  30
  • Publication
    Evaluation of GO and rGO on breast cancer cell line (MCF7) and normal breast cell line (MCF10a) for cell viability and electrical response
    (Universiti Malaysia Perlis (UniMAP), 2018-12)
    Siti S. Mat Isa
    ;
    N. S. Mazlan
    ;
    ;
    L. F. A. Talip
    ;
    Rafeezul Mohamed
    ;
    Graphene based materials become a phenomenal in various applications including biomedical devices due to their excellent properties. Their effects towards certain diseases were broadly studies and presented. However, the work has been performed was only limited to the graphene oxide (GO) and its biocompatibility only. In this work, the interaction of GO and reduced graphene oxide (rGO) on breast cancer cell (MCF7) and normal breast cell (MCF10a) was investigated specifically on the cell viability, cell mortality and current-voltage (IV) relationship. Graphene oxide and rGO at the concentration of 100μg/mL were prepared by chemical methods. The morphology and quality of both materials were characterized using AFM and Raman Spectroscopy. The cells were treated for 24 hours and the effects of these materials on the viability and mortality of the cell were observed. The interaction between graphene-based materials and both cells significantly impact the current-voltage (IV) characteristics. The results show that GO and rGO did not affect the cell viability but only small percentage different was obtained on cell mortality. It also observed that the resistance of cell treated with rGO decreased with time for MCF7 and vice versa for MCF10a. While for GO, the resistance of cell increased with time for MCF7 and vice versa for MCF10a. These clear patterns of these interactions lead to a good input for biosensor fabrication which was aimed to be used as the early diagnosis cancer stem cell point of care (POC) device.
  • Publication
    rGO-SWCNT hybrid for counter electrode in dye sensitized solar cell
    (Universiti Malaysia Perlis (UniMAP), 2018-12)
    M. R. Muda
    ;
    Siti S. Mat Isa
    ;
    Towards platinum free counter electrode in dye sensitized solar cells, some carbon-based materials like carbon nanotubes and graphene are fully utilized due to their extraordinary properties such as high aspect ratio and conductivity. In this paper, single-walled carbon nanotubes (SWCNT), reduced graphene oxide (rGO) and hybrid structure of rGO-SWCNT spray coated counter electrodes were compared with graphite as the reference material. The morphology of these materials was analyzed with FESEM and FTIR. The DSSC performance was then measured using solar simulator. The current-voltage (I-V) characteristics show that the rGO-SWCNT counter electrode result the excellent performance with efficiency of ~1.86 %, 95.2 % better than graphite. This higher performance was attributed by the complete oxygen-functional group removal during reduction process which offers large active surface area for electro-photocatalytic activity, higher conductivity, better structure and properties compared to the individual forms.
  • Publication
    Remazol orange dye sensitized solar cell using graphene oxide and reduced graphene oxide working electrode
    (Universiti Malaysia Perlis (UniMAP), 2018-12) ;
    Siti S. Mat isa
    ;
    ;
    N. Rosli
    Dye Sensitized Solar Cell (DSSC) is said as a potential solar device which offers easy, cheaper and greener materials and preparation process. However, the efficiency of this device is still an ultimate problem and challenge. In this paper, an organic Remazol orange dye was used as the DSSC dye sensitizer which prepared with different working electrodes. The different working electrodes consist of Titanium Dioxide (TiO2) with Graphene Oxide (GO) and TiO2 with reduced Graphene Oxide (rGO). In order to analyze the adsorption characteristics of GO and rGO, the solution was tested using Ultraviolet-Visible-Near Infrared Spectrophotometry and the surface morphology of all mixed pastes was observed under Atomic Force Microscopy and Scanning Electron Microscope. Then, the device performance was tested under illumination of solar cell simulator. From overall results, the efficiency for all tested devices was quite low from expectation. For this work, the performance of TiO2-rGO DSSC at 0.138% is 84.7% higher compared to the TiO2-GO DSSC which was 0.021%. This result was obtained when the working electrode and dye less exposed to the light during dye preparation process at 24 hours soaking time.