Now showing 1 - 10 of 18
  • Publication
    Fabrication of Graphene Electrode via Graphene Transfer Method for Bisphenol A (BPA) Detection
    Exposure of BPA is a concern as BPA can seep into food or beverages from containers and can possibly effects on human health especially endocrine systems. An electrochemical-based aptasensor utilizing graphene was developed in detecting endocrine disrupting compound Bisphenol A (BPA, 4,4'-(propane-2,2-diyl) diphenol). The graphene modified electrode was developed via graphene transfer. Fabrication and characterization of graphene transfer was studied in this paper using Scanning Electron Microscopy (SEM) and High-Power Microscope (HPM). In this research, the investigation of interfacial characteristic modified graphene with aptasensor and recognition of BPA with aptasensor had been done using electrochemical impedance spectroscopy (EIS). The increment of charge transfer resistance (Rct) before and after recognition of BPA denoting the accumulation of charge at the electrode surface in this research.
  • Publication
    Nanoparticle-based Biosensors for Detection of Heavy Metal Ions
    ( 2023-10-01)
    Beh Y.J.
    ;
    ; ;
    Chia S.B.
    ;
    Ng C.H.
    ;
    Ong C.C.
    ;
    Fathil M.F.M.
    ;
    Zailan Z.
    Heavy metal pollution is one of the most serious environmental problems in the world. Many efforts have been made to develop biosensors for monitoring heavy metals in the environment. Development of nanoparticle-based biosensors is the most effective way to solve this problem. This review presents the latest technology of nanoparticle-based biosensors for environment monitoring to detect heavy metal ions, which are magnetic chitosan biosensor, colorimetric biosensor, and electrochemical biosensor. Magnetic chitosan biosensor acts as a nano-absorbent, which can easily detect and extract poisonous heavy metal ions such as lead ions and copper ions. There are several methods to prepare the chitosan based on the nanoparticle, which are cross-linking, co-precipitation, multi-cyanoguanidine, and covalent binding method. In colorimetric biosensor, gold and silver nanoparticles are commonly used to detect the lead and mercury ions. In addition, this biosensor is very sensitive, fast and selective to detect metal ions based on the color change of the solution mixture. Meanwhile, electrochemical biosensor is widely used to detect heavy metal ions due to a simple and rapid process, easy, convenient and inexpensive. This biosensor is focused on the surface area, which leads to significant improvement in the performance of devices in terms of sensitivity. The wide surface area can affect the performance of the biosensor due to a limited space for operation of electrode. Therefore, reduced graphene oxide is a suitable material for making the electrochemical biosensor due to a wide surface area, good conductivity and high mechanical strength. In conclusion, these three technologies have their own advantages in making a very useful biosensor in the detection of heavy metal ions.
      1  20
  • Publication
    Nanoparticle-based biosensors for detection of heavy metal ions
    Heavy metal pollution is one of the most serious environmental problems in the world. Many efforts have been made to develop biosensors for monitoring heavy metals in the environment. Development of nanoparticle-based biosensors is the most effective way to solve this problem. This review presents the latest technology of nanoparticle-based biosensors for environment monitoring to detect heavy metal ions, which are magnetic chitosan biosensor, colorimetric biosensor, and electrochemical biosensor. Magnetic chitosan biosensor acts as a nano-absorbent, which can easily detect and extract poisonous heavy metal ions such as lead ions and copper ions. There are several methods to prepare the chitosan based on the nanoparticle, which are cross-linking, co-precipitation, multi-cyanoguanidine, and covalent binding method. In colorimetric biosensor, gold and silver nanoparticles are commonly used to detect the lead and mercury ions. In addition, this biosensor is very sensitive, fast and selective to detect metal ions based on the color change of the solution mixture. Meanwhile, electrochemical biosensor is widely used to detect heavy metal ions due to a simple and rapid process, easy, convenient and inexpensive. This biosensor is focused on the surface area, which leads to significant improvement in the performance of devices in terms of sensitivity. The wide surface area can affect the performance of the biosensor due to a limited space for operation of electrode. Therefore, reduced graphene oxide is a suitable material for making the electrochemical biosensor due to a wide surface area, good conductivity and high mechanical strength. In conclusion, these three technologies have their own advantages in making a very useful biosensor in the detection of heavy metal ions.
      4  23
  • 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.
      40  1
  • 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.
      3  32
  • Publication
    A Controlled Growth of Carbon Nanofibers (CNFs) on Graphene
    ( 2023-12-01)
    Fiyatillah M.
    ;
    ; ;
    Kita L.K.W.
    ;
    ; ;
    Abd Rahim A.F.
    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.
      3  36
  • 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.
      3  29
  • Publication
    Carbon Nanofibers (CNFs) Synthesis on Graphene/Ni Thin Film: An Analysis on the Effect of Carrier Gas Flow Rate
    ( 2023-01-01)
    Fiyatillah M.
    ;
    ; ;
    Kita L.K.W.
    ;
    Jun H.Q.
    ;
    ; ;
    Abd Rahim A.F.
    The pursuit of high-performance materials for interconnects and electrodes in various electronic applications has led to the exploration of carbon nanotubes (CNTs)-graphene hybrid materials due to their potential to surpass copper (Cu) in terms of thermal conductivity. This study aimed to grow CNTs on graphene. However, the applied growth parameters led to the formation of carbon nanofibers (CNFs) on graphene. CNFs-graphene hybrids may have lower thermal conductivity compared to CNTs-graphene hybrids. This investigation aims to understand the growth evolution of the CNFs at a varied carrier gas flow rate. This work investigates the CNFs' growth on graphene on a nickel (Ni) thin film substrate under a growth temperature of 860°C in 2 hours. By varying the gas flow rate, this research aims to discern the optimal conditions for achieving controllable CNFs growth on graphene. This work found that the higher carrier gas flow rate led to better formation of CNFs with a more uniform coverage and smaller width. The XRD results confirm the formation of CNFs on graphene.
      2  34
  • Publication
    Hexagonal enhanced porous GaN with delayed integrated pulse electrochemical (iPEC) etching
    ( 2024-10)
    Nurul Syuhadah Mohd Razalia
    ;
    Alhan Farhanah Abd Rahim
    ;
    Nur Sabrina Mohd Hassan
    ;
    Rosfariza Radzali
    ;
    Ainorkhilah Mahmood
    ;
    ;
    Irni Hamiza Hamzah
    ;
    Mohaiyedin Idris
    ;
    Mohamed Fauzi Packeer Mohamed
    This present study investigates the effect of time delay (Td) on the formation of porous GaN (P-GaN) using integrated pulse electrochemical (iPEC) etching. Porous GaN (P-GaN) was formed by etching an N-type GaN wafer with a 4% KOH electrolyte for 60 minutes under an ultraviolet (UV) lamp at a current density of 80 mA/cm2. A Td of 120 minutes was applied before electrochemically etching the P-GaN sample. The top view image of the field emission scanning electron microscopy (FESEM) revealed a significant difference when a Td was applied. A dense and uniform hexagonal P-GaN was obtained from the Td iPEC sample, while the non-Td sample exhibited a multi-layered hexagonal porous structure with unfinished pore-etched areas. Higher porosity and deeper pores were observed in the Td sample. Intense high-resolution X-ray diffraction (HR-XRD) peak intensity was observed in the Td iPEC sample with a lower full width half maximum (FWHM), indicating that the sample had better crystallinity. The Raman spectra of the sample anodized with a Td exhibited higher Raman peak intensity and a slight shift to a higher frequency concerning as-grown GaN, indicating better crystallinity and a tensile stress relaxation of 0.24 GPa. Post etching, a blue shift of the photoluminescence (PL) peak, from 364 nm (as-grown GaN) to 363 nm (P-GaN), was observed, and a small PL peak started to form around 385 nm compared to the as-grown GaN due to the relaxation of the tensile stress, which modified the bandgap. The PL peak intensity of the Td sample was higher than the non-Td sample, indicating that the porosity and uniformity allowed more light interaction with the material, resulting in more efficient photon absorption and emission. The results indicated that potentially efficient optoelectronics devices can be fabricated on a P-GaN using a combination of electroless and electrochemical etching of the GaN epitaxial layer.
      19  2
  • Publication
    A study on the impact of silicon-on-nothing (SON) versus silicon-on-insulator (SOI) on the electrostatic performance of a transistor
    (Universiti Malaysia Perlis (UniMAP), 2018-12) ; ;
    In this work, we investigate the impact of employing silicon-on-nothing (SON) versus silicon-on-insulator (SOI) on the electrostatic performance of a transistor with various ground-plane (GP) structures of Lg = 10 nm through the use of Sentaurus TCAD simulator. The digital figure-of-merit (FoM) of interest includes the results of drain-induced barrier lowering (DIBL) which is a major indicator of a control of short-channel effects (SCEs). It is found that SOI devices produce a lower off-current (Ioff) as compared to SON. In terms of the different GP architectures, the introductions of various GP architectures were found to affect the values of DIBL in SOI whereas the impact on SON is negligible. It can be concluded that GP-B architectures with ground plane underneath the channel areas of SOI is most effective in suppressing substrate depletion effects as evidenced from the lowest DIBL produces.
      1  15