UniMAP RIS :: Browsing by Department "Faculty of Electronic Engineering & Technology"

Publication

A review of visible-to-UV photon upconversion systems based on triplet–triplet annihilation photon upconversion

( 2022-12)

Kelvin Voon Yan Jie

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Safizan Shaari

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Arif Mawardi Ismail

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Yusran Sulaiman

Due to the tunable spectrum range and potential application under non-coherent solar irradiation, triplet-triplet annihilation based molecular photon upconversion (TTA-UC) systems represent a compelling study field for a variety of photonic implementations. There were studies on the incorporation of TTA-UC technology with photovoltaic technology, which made it possible to further improve the energy harvest performance through the utilisation of the wasted spectrum. However, many TTA-UC studies are limited to energy upconversion within the visible spectrum range. For photovoltaic cells with a higher band gap, which harvest the higher energy spectrum (UV region), an efficient Vis-to-UV upconversion is preferred. The Vis-to-UV TTA-UC system was first introduced in 2006. Recently, more studies were conducted to discover the Vis-to-UV upconversion system with high quantum efficiency and low excitation intensity such as the nanocrystal sensitizerbased system and the thermally activated delayed fluorescence sensitizer-based system. Recent studies in the solvent system of Vis-to-UV upconversion system had demonstrated the dependence of the couple photostability on the solvent and extended the solvent selection to inorganic solvent. In this review, we are reviewing the research background of the Vis-to-UV TTA-UC system and discussing the current challenges and potential developments in this research area.

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Publication

Banana stem waste as a sustainable modifier for microstructure modification of protonic ceramic fuel cell cathode

( 2024-06)

Ismariza Ismail

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Norizah Abd Karim

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Abdullah Abdul Samat

This study investigates the feasibility of utilizing banana stem waste (BSW) as a pore former to modify the microstructure of the PCFC composite cathode. The microstructure of the La₀.₆Sr₀.₄Co₀.2Fe₀.8O3-α-Ba(Ce₀.₆Zr₀.₄)₀.₉Y₀.1O3-δ (LSCF-BCZY64) composite cathode was modified by varying the amounts of the incorporated banana stem waste. The samples underwent sintering at 1000 ˚C, and their microstructural and physical properties were analyzed using X-ray diffraction, scanning electron microscopy, and densimeter. The results indicate that the incorporation of BSW enhances the porosity of the cathode without significantly affecting its crystalline structure. As the amount of BSW increased from 10 to 40 wt.%, the porosity level increased from 7.0% to 32.7%, and the density of the samples decreased from 1.3 to 0.9 g/cm3, thereby supporting the results of the porosity analysis. Increased cathode porosity can enhance reactant accessibility to active sites, potentially resulting in improved cell performance and durability. Moreover, the utilization of BSW as a sustainable and cost-effective pore former aligns with the growing emphasis on environmentally friendly materials in energy applications.

Publication

Characterization of Excimer Laser Micromachining Parameters to Derive Optimal Performance for the Production of Polydimethylsiloxane (PDMS)-based Microfluidic Devices

( 2024-01-01)

Shazlina Johari

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Ting Z.K.

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Mazlee Mazalan

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Yufridin Wahab

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Anas Mohd Noor

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Laser micromachining has been used as an alternative to producing microfluidics structures and simplifying the conventional soft lithography process. In this paper we characterize the excimer laser micromachining parameters and demonstrate its application by producing several microfluidic structures in polydimethylsiloxane (PDMS). The parameters include the number of laser pulses, laser energy and rectangular variable aperture (RVA) in both x- and y-directions. We found that the laser energy and pulse rate affect the depth of micromachining d channels, while RVA in both x- and y-directions affects the width of the channels. Repetition of laser scan does not change the channel width but significantly changes the channel depth. Proper adjustment for laser energy and pulse rate is required to fabricate a desired channels depth. In order to demonstrate the microfabrication capability of an excimer laser with the optimal operating parameters, several microfluidic structures were micromachining d into PDMS with a KrF excimer laser.

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Publication

Comprehensive study on gate recess step for the fabrication of high-speed InGaAs/InAlAs/InP pHEMT

( 2017-01-03)

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Siti Salwa Mat Isa

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Nurul Izza Mohd Nor

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Missous M.

We report a comprehensive etching study on the gate recess step for the fabrication of the novel high speed pHEMT devices. The experiments focused on the elimination of 'hump' structure as a result of an incomplete etching process at the InGaAs cap layer. In this work, two types of test samples were used, namely bulk InGaAs and epitaxial structure together with an etch stop layer. The result showed that the etch rate of bulk InGaAs is about 360 A/min and the percentage of dome height is consistent at approximately 25%. Meanwhile, the study on pHEMT epitaxial layer showed that the etching time of 3 minutes is sufficient in order to completely remove the cap layer. Gate leakage current of magnitude more than 10 times lower is observed on the devices that engaging Succinic Acid as the gate recess etching agent. The optimized processing steps will tailor for highly reproducible pHEMT fabrication process for high speed applications.

Publication

Effect of isothermal annealing on Sn whisker growth behavior of Sn0.7Cu0.05Ni solder joint

( 2023)

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Andrei Victor Sandu

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Petrica Vizureanu

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Ioan Gabriel Sandu

This paper presents an assessment of the effect of isothermal annealing of Sn whisker growth behavior on the surface of Sn0.7Cu0.05Ni solder joints using the hot-dip soldering technique. Sn0.7Cu and Sn0.7Cu0.05Ni solder joints with a similar solder coating thickness was aged up to 600 h in room temperature and annealed under 50 °C and 105 °C conditions. Through the observations, the significant outcome was the suppressing effect of Sn0.7Cu0.05Ni on Sn whisker growth in terms of density and length reduction. The fast atomic diffusion of isothermal annealing consequently reduced the stress gradient of Sn whisker growth on the Sn0.7Cu0.05Ni solder joint. It was also established that the smaller (Cu,Ni)6Sn5 grain size and stability characteristic of hexagonal η-Cu6Sn5 considerably contribute to the residual stress diminished in the (Cu,Ni)6Sn5 IMC interfacial layer and are able to suppress the growth of Sn whiskers on the Sn0.7Cu0.05Ni solder joint. The findings of this study provide environmental acceptance with the aim of suppressing Sn whisker growth and upsurging the reliability of the Sn0.7Cu0.05Ni solder joint at the electronic-device-operation temperature.

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Publication

Effect of isothermal annealing on Sn whisker growth behavior of Sn0.7Cu0.05Ni solder joint

( 2023)

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Andrei Victor Sandu

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Petrica Vizureanu

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Ioan Gabriel Sandu

This paper presents an assessment of the effect of isothermal annealing of Sn whisker growth behavior on the surface of Sn0.7Cu0.05Ni solder joints using the hot-dip soldering technique. Sn0.7Cu and Sn0.7Cu0.05Ni solder joints with a similar solder coating thickness was aged up to 600 h in room temperature and annealed under 50 °C and 105 °C conditions. Through the observations, the significant outcome was the suppressing effect of Sn0.7Cu0.05Ni on Sn whisker growth in terms of density and length reduction. The fast atomic diffusion of isothermal annealing consequently reduced the stress gradient of Sn whisker growth on the Sn0.7Cu0.05Ni solder joint. It was also established that the smaller (Cu,Ni)6Sn5 grain size and stability characteristic of hexagonal η-Cu6Sn5 considerably contribute to the residual stress diminished in the (Cu,Ni)6Sn5 IMC interfacial layer and are able to suppress the growth of Sn whiskers on the Sn0.7Cu0.05Ni solder joint. The findings of this study provide environmental acceptance with the aim of suppressing Sn whisker growth and upsurging the reliability of the Sn0.7Cu0.05Ni solder joint at the electronic-device-operation temperature.

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Publication

Effect of Ni on the suppression of sn whisker formation in Sn-0.7Cu solder joint

( 2021)

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Andrei Victor Sandu

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Khor Chu Yee

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Noor Zaimah Mohd Mokhtar

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Jitrin Chaiprapa

The evolution of internal compressive stress from the intermetallic compound (IMC) Cu6Sn5 growth is commonly acknowledged as the key inducement initiating the nucleation and growth of tin (Sn) whisker. This study investigates the effect of Sn-0.7Cu-0.05Ni on the nucleation and growth of Sn whisker under continuous mechanical stress induced. The Sn-0.7Cu-0.05Ni solder joint has a noticeable effect of suppression by diminishing the susceptibility of nucleation and growth of Sn whisker. By using a synchrotron micro X-ray fluorescence (µ-XRF) spectroscopy, it was found that a small amount of Ni alters the microstructure of Cu6Sn5 to form a (Cu,Ni)6Sn5 intermetallic layer. The morphology structure of the (Cu,Ni)6Sn5 interfacial intermetallic layer and Sn whisker growth were investigated by scanning electron microscope (SEM) in secondary and backscattered electron imaging mode, which showed that there is a strong correlation between the formation of Sn whisker and the composition of solder alloy. The thickness of the (Cu,Ni)6Sn5 IMC interfacial layer was relatively thinner and more refined, with a continuous fine scallop-shaped IMC interfacial layer, and consequently enhanced a greater incubation period for the nucleation and growth of the Sn whisker. These verification outcomes proposes a scientifically foundation to mitigate Sn whisker growth in lead-free solder joint.

Publication

Effect of Ni on the suppression of Sn whisker formation in Sn-0.7Cu solder joint

( 2021)

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Andrei Victor Sandu

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Khor Chu Yee

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Noor Zaimah Mohd Mokhtar

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Jitrin Chaiprapa

The evolution of internal compressive stress from the intermetallic compound (IMC) Cu6Sn5 growth is commonly acknowledged as the key inducement initiating the nucleation and growth of tin (Sn) whisker. This study investigates the effect of Sn-0.7Cu-0.05Ni on the nucleation and growth of Sn whisker under continuous mechanical stress induced. The Sn-0.7Cu-0.05Ni solder joint has a noticeable effect of suppression by diminishing the susceptibility of nucleation and growth of Sn whisker. By using a synchrotron micro X-ray fluorescence (µ-XRF) spectroscopy, it was found that a small amount of Ni alters the microstructure of Cu6Sn5 to form a (Cu,Ni)6Sn5 intermetallic layer. The morphology structure of the (Cu,Ni)6Sn5 interfacial intermetallic layer and Sn whisker growth were investigated by scanning electron microscope (SEM) in secondary and backscattered electron imaging mode, which showed that there is a strong correlation between the formation of Sn whisker and the composition of solder alloy. The thickness of the (Cu,Ni)6Sn5 IMC interfacial layer was relatively thinner and more refined, with a continuous fine scallop-shaped IMC interfacial layer, and consequently enhanced a greater incubation period for the nucleation and growth of the Sn whisker. These verification outcomes proposes a scientifically foundation to mitigate Sn whisker growth in lead-free solder joint.

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Publication

Effect of polyethylene glycol and sodium dodecyl sulphate on microstructure and self-cleaning properties of graphene oxide/TiO2 thin film

( 2020-09-01)

Azani A.

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Dewi Suriyani Che Halin

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Kamrosni Abdul Razak

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Norsuria Mahmed

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Mohd Fairul Sharin Abdul Razak

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Ayu Wazira Azhari

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Chobpattana V.

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Kaczmarek L.

In this study, a sol gel procedure for preparation of TiO2 thin films with graphene oxide (GO) was developed. The effect of PEG and SDS addition on the microstructure of the films as well as the photocatalytic activity of the thin film was also investigated. The morphology and surface structure of the films were studied by SEM and AFM while the photocatalytic activity of the films was analyzed by measuring the degradation of methylene blue under sunlight irradiation using UV-Vis spectrophotometer. It was found that GO/TiO2 thin film with PEG shows a smaller and porous particle while GO/TiO2 thin film with SDS formed a very smooth surface and very fine particles. Therefore, in AFM analysis reveals that surface roughness decreases with the addition of PEG and SDS. Finally, the photocatalytic activity showed that GO/TiO2 thin film with SDS have the most effective self-cleaning property which degrade 64% of methylene blue that act as model of contaminants.

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Publication

Effect of sodium ion addition on copper selenide/chitosan film towards electrical and shielding efficiency improvement

( 2024-06)

Nurul Najiha Mazu

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Hazeem Ikhwan Mazlan

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Josephine Ying Chyi Liew

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Nurul Huda Osman

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Ali Reshak

The operation of electronic devices can be disrupted by unwanted electromagnetic signals, affecting its operation. Deploying electromagnetic shielding is a viable solution to minimize the impact of electromagnetic interference (EMI). The conventional methods of electromagnetic shielding use metal gaskets to safeguard sensitive electronic components, which have drawbacks of cost and weight. Hence, electromagnetic shielding polymer can be an alternative to replace metal gaskets. This work investigates the effect of sodium ion (Na) addition to copper selenide/chitosan (CuSe/Ch) film for electromagnetic shielding applications. The shielding polymers were produced using solution casting methods, while the CuSe was synthesized using the chemical coprecipitation method. Impedance spectroscopy and two port waveguide methods were used to characterize the prepared polymer's electrical properties and shielding efficiency. The results indicate that Na incorporation in the CuSe/Ch film resulted in a 47 % decrease in bulk resistivity and increased DC conductivity from 6.07 × 10-6 S/cm to 3.69 × 10˗5 S/cm. The AC conductivity of films containing Na demonstrates a similar level of conductivity at lower frequencies, followed by a sharp increase at higher frequencies, indicating a more substantial influence of Na at higher frequencies. Higher absorption shielding efficiency (SEA) and lower reflection shielding efficiency (SER) were achieved by introducing Na into the CuSe chitosan film. The Na/CuSe/Ch film shows higher total shielding efficiency at an average of 20 dB, equivalent to 99 % of the EM power shield.

Publication

Fabrication of Strontium Titanate thin film with pre-crystallized layer via sol-gel spin coating method

( 2022-12)

Kelvin Voon Yan Jie

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Safizan Shaari

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Arif Mawardi Ismail

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Yusran Sulaiman

The technique of pre-crystallized layer is introduced in the strontium titanate (STO) thin film fabrication to improve the coating thickness and the crystallinity. The STO thin films were fabricated on glass substrates via the spin coating method with STO precursor solution that was synthesized through the sol-gel process. The characteristics of the thin films were analyzed through X-ray diffraction (XRD) analysis, profilometry, UV-Vis spectra analysis and scanning electron microscopy (SEM) analysis. In the present study, the samples of 20 layers and 25 layers (deposited on the pre-crystallized layer) exhibited better crystallinity as compared with the samples of 5 layers, 10 layers and 15 layers (without the pre-crystallized layer). The samples of 25 layers exhibited the highest film thickness (224 nm), highest absorbance intensity and the highest XRD peak intensity at 32, 40, 47 and 58°, which represent the planes (110), (111), (200) and (210), respectively. The pre-crystallized layer served as the mechanical support for further layer deposition.

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Publication

Film bulk acoustic wave resonator in 10-20 GHz frequency range

( 2017-01-03)

Nurul Izza Mohd Nor

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Siti Salwa Mat Isa

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This paper presents the design and optimisation of film bulk acoustic wave resonator (FBAR) using nano electro mechanical systems (NEMS) technology in 10-20 GHz frequency band. The effect of thickness, width and length and damping factor of the FBAR are analysed. The air-gap FBAR are designed due its ability to achieve high quality (Q) factor in 10-20 GHz frequency band. The proposed designs achieve a constant electromechanical coupling coefficient for 10-20 GHz. Analysis shows the Q varies highly dependent on the damping factor. The results show that the proposed design achieves almost double the Q factor at 15 GHz and 20 GHz operation when compared to similar designs.

Publication

Geopolymer Ceramic as Piezoelectric Materials: A Review

( 2020-07-09)

Ahmad R.

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Wan Mastura Wan Ibrahim

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Victor Sandhu A.

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Nurul Aida Mohd Mortar

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Waried Wazien Ahmad Zailani

Diverse application for geopolymer so called inorganic polymer have been expanded as potential to continue growing at a realistic rate where the properties, processing tolerance and economical are comparable with the existing materials. An aluminosilicate inorganic polymer can be produced at low temperature under highly alkali conditions from a solid aluminosilicate and an alkali silicate solution. The conversion of amorphous to semi-crystalline behaviour of geopolymer into crystalline phases upon heating make the method be an alternate way in producing ceramic materials. For another application related to high temperature packaging and enclosure of electronical devices, piezoelectric behavior turn out to be important properties to the geopolymer ceramic materials. This paper summarize the review on the important research findings on the basic geopolymer systems, current knowledge of geopolymer ceramic, and outline potential piezoelectric effect on ceramic materials.

Publication

Interdigitated electrodes as impedance and capacitance biosensors: A review

( 2017-09-26)

Mazlan N.

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Dewi Suriyani Che Halin

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Isa S.

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Talip L.

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Nuaim Siddiqi Danial

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Sohiful Anuar Zainol Murad

Interdigitated electrodes (IDEs) are made of two individually addressable interdigitated comb-like electrode structures. IDEs are one of the most favored transducers, widely utilized in technological applications especially in the field of biological and chemical sensors due to their inexpensive, ease of fabrication process and high sensitivity. In order to detect and analyze a biochemical molecule or analyte, the impedance and capacitance signal need to be obtained. This paper investigates the working principle and influencer of the impedance and capacitance biosensors. The impedance biosensor depends on the resistance and capacitance while the capacitance biosensor influenced by the dielectric permittivity. However, the geometry and structures of the interdigitated electrodes affect both impedance and capacitance biosensor. The details have been discussed in this paper.

Publication

Linear modelling of novel InGaAs/InAlAs/InP pHEMT for low noise applications

( 2017-01-03)

En A.Y.

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Siti Salwa Mat Siti

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Nurul Izza Mohd Nor

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Missous M.

Linear modelling of novel InGaAs/InAlAs/InP pHEMT for low noise applications is substantial to the future transistors that will operate in high speed and low noise conditions. The novel pHEMT is constructed by sandwiching two different materials together with different lattice constants, for instance InGaAs and InAlAs in order to form a heterojunction in between. However, InP is only utilised to be the substrate base of pHEMT. In the modelling process, extrinsic and intrinsic parameters need to be extracted. Briefly, a high accuracy transistor modelling enables designers to predict the real output of a circuit before it can be fabricated onto an actual chip.

Publication

Mesoporous Structure of Doped and Undoped PEG on Ag/TiO2 Thin Film

( 2019-08-14)

Abdul Razak K.

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Dewi Suriyani Che Halin

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Azani A.

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Norsuria Mahmed

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Sepeai S.

In this reaserch, photocatalyst silver titanium dioxide was doped and modified by Polyethylene Glycol (PEG). The purpose of the present study was to analyse the synthesized Ag/TiO2 thin film doped and undoped PEG. Ag/TiO2 thin films on silicon wafer have been prepared by sol-gel spin coating. The samples were characterized by Grazing Incidence X-ray diffraction (GIXRD), Field Emission Scanning Electron Microscopy (FESEM) and Atomic Force Microscope (AFM). The doped and undoped PEG Ag/TiO2 thin films showed a mesoporous TiO2 matrix which includes TiO2 crystallites of 10-20 nm in size and small Ag nanoparticles (white spots) with various sizes ranging from 10 to 30 nm. However, doped PEG Ag/TiO2 thin film showed the Ag nanoparticles became agglomerates but still remained roughly uniform on the surface.

Publication

Production of low temperature synthetic graphite

( 2023-04)

Anis Syafiqa Rosman

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Ranjitha Navalan

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Norizah Abd Karim

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Shazlina Johari

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Norshamsuri Ali @ Hasim

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Nurul Huda Osman

Synthetic graphite is a material consisting of graphitic carbon which has been obtained by graphitizing a non-graphitic carbon. The growth in demand, particularly in customizing properties for certain usage has brought about research on viable alternative, low-cost, and environmentally pleasant synthetic graphite production. Biomass wastes are amongst appealing carbon precursors which have been broadly checked out as replacement carbon for graphite production. This research aimed to synthesize synthetic graphite from oil palm trunks at low temperatures (500 °C, 400 °C and 300 °C) under controlled conditions to determine the physical properties and properties of the graphite obtained. After the heat treatment process, the obtained samples were then characterized by using XRD, SEM and RAMAN characterizations. Based on SEM and RAMAN characterization, it can be seen that graphite that undergoes a 500 °C pyrolysis process shows the best results compare to graphite that undergoes a pyrolysis process at the temperatures of 300 °C and 400 °C. The graphite flakes and the peaks obtained for 500 °C graphite are obviously present. For XRD characterization, the best samples at 500 °C were chosen to be characterized. From the results, the sample shows slight behavior imitating the commercialized graphite. Hence, from the characterizations of the samples, it can be concluded that the best synthetic graphite produced was from the oil palm trunks heated at 500 ° C

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Publication

Remazol orange dye sensitized solar cell

( 2017-01-03)

Siti Salwa Mat Isa

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Nor Azura Malini Ahmad Hambali

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Muda M.R.

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Nurul Izza Mohd Nor

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Nur M. Selamat

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Nur Asyikin Mohd Anhar

Water based Remazol Orange was utilized as the dye sensitizer for dye sensitized solar cell. The annealing temperature of TiO2 working electrode was set at 450 °C. The performance of the device was investigated between dye concentrations of 0.25 mM and 2.5 mM at three different immersion times (3, 12 and 24 hours). The adsorption peak of the dye sensitizer was evaluated using UV-Vis-Nir and the device performance was tested using solar cell simulator. The results show that the performance was increased at higher dye concentration and longer immersion time. The best device performance was obtained at 0.2% for dye concentration of 2.5 mM immersed at 24 hours.

Publication

Single wall carbon nanotubes dispersion study of different dye molecules and chitosan

( 2017-09-26)

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Siti Salwa Mat Isa

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