Ismariza Ismail
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Preferred name
Ismariza Ismail
Official Name
Ismail, Ismariza
Alternative Name
Ismail, I.
Ismail, Ismariza
Main Affiliation
Scopus Author ID
57203013485
Researcher ID
GTH-8854-2022

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Characterization of LSCF cathode material modified with f-CNTs

2020-07 , Nurul Izzati Abd Malek , Ismariza Ismail , Nafisah Osman

Cathode is one of the important parts in performing the high efficiency of proton conducting fuel cell (PCFC). Selection of appropriate cathode material may resolve the major drawbacks at the cathode part associated with the high Rp. Accordingly, tremendous effort have been done to reduce the Rp and one of the alternatives is the modification of cathode microstructure that can be achieved by introducing dispersing agent in the synthesis route. Thus, in this present work, a functionalized carbon nanotubes (f-CNTs) obtained from acidification process was used as a dispersing agent in the synthesis of La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) cathode material. The amount of 4 mg, 8 mg and 12 mg of f-CNTs were respectively added to LSCF cathode during the synthesizing process by a sol-gel method. Semi-solid gel obtained was calcined at 900 ˚C to form high purity of LSCF powder and respectively denoted as LSCF4, LSCF8 and LSCF12. The powder was characterized by Fourier Transform Infrared (FTIR) Spectroscopy, Pycnometer, Particle Size Analyzer and Scanning Electron Microscopy with Energy Dispersive X-ray (SEM/EDX). The FTIR analysis depicted the peak of respective metal complexes, metal oxide, symmetrical and asymmetrical stretching of carboxylate. The pycnometer showed the lowest density of LSCF4 was 2.8777 g/cm3. The Particles Size Analyzer confirmed the particle size of 38 nm ultrafine powder for LSCF4. The SEM image depicted the highly disperse spherical particles found in LSCF4 with particle size about 30 nm. The elemental composition of the samples is comparable with the nominal stoichiometric of LSCF4 as corroborated by the EDX analysis. Therefore, the LSCF with optimum 4 mg f-CNTs as dispersing agent has potential as nanoporous cathode material for proton conductivity fuel cell.

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La₀.₆Sr₀.₄Co₀.₂Fe₀.₈O₃−δ powder: a simple microstructure modification strategy for enhanced cathode electrochemical performance

2020 , Ismariza Ismail , Nafisah Osman , Abdul Mutalib Md Jani

A simple strategy of producing well-dispersed La₀.₆Sr₀.₄Co₀.₂Fe₀.₈O₃−δ (LSCF) cathode nanopowders that utilizes a dispersing agent is presented. The cathode nanopowder was synthesized by employing a dispersing agent-assisted sol–gel method. Two types of dispersing agents were applied as the synthesizing aids in this study which are the activated carbon (AC) and ethylene glycol (EG). The synthesized cathode powder was systematically characterized by X-ray diffraction (XRD), thermogravimetric analyzer (TGA), field emission scanning electron microscopy (FESEM), and BET surface area analyzer. The electrochemical properties of the fabricated cell were evaluated using electrochemical impedance spectroscopy (EIS). TGA analysis shows that both dispersing agents decomposed below 600 °C. The XRD analysis demonstrates that the single-phase LSCF perovskite is attainable at the calcination temperature of 700 °C for 5 h. FESEM results are in accordance with the BET analysis in which application of the dispersing agents produced more dispersed cathode powders and larger surface area. The electrochemical performances of the LSCF cathode modified with the AC and EG are respectively in the average of six- and eightfolds higher as compared with the pristine LSCF. The dispersing reaction of AC and EG and their influences on the cathode microstructure and performance are also thoroughly discussed.

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Development of MCSF (M=La, Ba) cathode materials for proton conducting fuel cell application

2020-03 , Nafisah Osman , Nurul Izzati Abd Malek , Ismariza Ismail , Anisah Shafiqah Habiballah , Abdul Mutalib Md Jani

Two cathode materials for proton-conducting fuel cell (PCFC), La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) and Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF) were investigated regarding their microstructural and electrical properties under air containing atmosphere. The respective sample was prepared via a modified sol-gel method using an activated carbon as a dispersing agent and anodic aluminium oxide (AAO) templating method assisted with sol-gel process. The powders were subjected to X-ray Diffractometer (XRD) and Brunauer-Emmet-Teller (BET). A symmetrical half-cell of LSCF|BCZY|LSCF and BSCF|BCZY|BSCF (BCZY = BaCe0.54Zr0.36Y0.1O2.95)was fabricated and characterized using an electrochemical impedance spectroscopy (EIS) and scanning electron microscope (SEM). After calcined at T = 900 °C, both of the LSCF and BSCF demonstrated their single-phase structure and exhibited highly dispersed powders with large surface area as proven by BET result. For electrical analyses, impedance spectrum of the cathodes was referred only to the two main contributions of cathode responses which were charge transfer at cathode/electrolyte interface and oxygen adsorption/dissociation on the cathode surface. At 600 °C, the polarization resistance of LSCF half-cell (Rp = 4.94 ω.cm2) was comparable to BSCF (Rp = 4.50 ω.cm2). SEM images revealed no delamination along the electrolyte/ electrode interface after EIS measurements as no sign of crack was observed for both samples. It can be concluded that the microstructure of the cathode layer can be tailored by altering the sample's preparation route which in turn to enhance the PCFC performance.

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Characterization of LaSrCoFeO₃ cathode material prepared with the aid of functionalized carbon nanotubes for proton conducting fuel cell

2020 , Nurul Izzati Abd Malek , Ismariza Ismail , Abdul Mutalib Md Jani , Nafisah Osman

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