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Impact of Dimethylformamide/Acetone Ratios and Stirring Time on Morphology and Electrical Properties of Electrospun PVDF Fibers
(2025-01-01)
Hakimi Bin Ismail, M. I.
;
Syed Bakar, S. S.
;
Yahud, S.
;
Chaisitsak, S.
This study examines the impact of Dimethylformamide, DMF/Acetone ratio (60/40, 70/30 and 100/0) and stirring time (16 hours and 24 hours) on Polyvinylidene Fluoride electrospun fibers. Total of six samples were prepared at 12% solution con-centration were electrospun at 20 kV, 10 cm tip-to-collector distance, and 1 mL/h flow rate. Morphological analysis showed that a 70/30 ratio produced finer fibers with fewer beads than 60/40 ratio, while prolonged stirring increased fiber diameter. Electrical analysis confirmed the lowest resistance and highest conductivity for these fibers. The 70/30 ratio and 16-hour stirring time technique optimized fiber structure and electrical performance for advanced applications.
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Fast-LPG Sensors at Room Temperature by α -Fe2O3/CNT Nanocomposite Thin Films
(2018-01-01)
Chaitongrat, B.
;
Chaisitsak, S.
We present performance of a room temperature LPG sensor based on α-Fe2O3/CNT (carbon nanotube) nanocomposite films. The nanocomposite film was fabricated via the metallic Fe catalyst particle on CNTs in which both the catalyst particles and the CNT were simultaneously synthesized by chemical vapor deposition (CVD) synthesis and were subsequently annealed in air to create α-Fe2O3. These methods are simple, inexpensive, and suitable for large-scale production. The structure, surface morphologies, and LPG response of nanocomposite films were investigated. Raman spectroscopy and XPS analysis showed the formation of α-Fe2O3 on small CNTs (SWNTs). Morphological analysis using FE-SEM and AFM revealed the formation of the porous surface along with roughness surface. Additionally, the sensing performance of α-Fe2O3/CNTs showed that it could detect LPG concentration at lower value than 25% of LEL with response/recovery time of less than 30 seconds at room temperature. These results suggest that the α-Fe2O3/CNTs films are challenging materials for monitoring LPG operating at room temperature.
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Spray deposited CuInS2/TiO2 thin film solar cells
(2013-09-02)
Kaliang, J.
;
Chaisitsak, S.
Copper indium sulfide (CIS) solar cells with Ag/CIS/TiO<inf>2</inf>/FTO/ glass structure were fabricated by non-vacuum methods. The nanoporous TiO <inf>2</inf> and nanocrystalline CIS films were prepared by screen-printing and spray pyrolysis techniques, respectively. The obtained films were examined using field-emission scanning electron microscopy and X-ray diffraction. The solar cell properties were characterized under AM 1.5. The porous nature of TiO <inf>2</inf> layer was found to cause the formation of nanocrystalline CIS with a very small grain size within the TiO<inf>2</inf> matrix. The photocurrent could not be observed in any devices without a TiO<inf>2</inf> layer (i.e. CIS/FTO), while it was detected for the devices consisting of TiO<inf>2</inf> layer (i.e. CIS/TiO<inf>2</inf>/FTO). The thickness of TiO<inf>2</inf> layer was optimized for maximum efficiency. The highest efficiency obtained solar cells was 2.3 × 10-5 % (V<inf>oc</inf>: 0.147 V, J<inf>sc</inf>: 6.5×10-7A/cm2, FF: 0.24) with a 3-μm-thick TiO<inf>2</inf>. © 2013 IEEE.
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F-doped nanocrystalline SnO2 thin films for liquid petroleum gas (LPG) sensors
(2011-10-04)
Chaisitsak, S.
In this paper we reported the improvement sensing performance of nanocrystalline SnO<inf>2</inf> thin film based LPG sensors by doping with fluorine. Un-doped and F-doped tin oxide films were prepared on glass substrates by dip-coating technique using a layer-by-layer deposition cycle (alternating between dip-coating a thin layer followed by a drying in air after each new layer). The results showed that this technique is superior to the conventional technique for both improving the film thickness uniformity and film transparency. Atomic Force Microscopy (AFM) and X-ray diffraction pattern measurements showed that the obtained thin films were nanocrystalline SnO <inf>2</inf>. Gas sensing characteristics (sensor response, response/recovery time and repeatability) of the nanocrystalline SnO<inf>2</inf> sensors based on a planar interdigital structure were investigated at different operating temperatures and different LPG concentrations. The addition of fluorine to SnO<inf>2</inf> was found to be advantageous for efficient detection of LPG gases, e.g. F-doped sensors were more stable at low operating temperature and had higher sensor response and faster response/recovery time, compared to un-doped sensor material. © 2011 IEEE.
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Graphite-encapsulated iron particles grown by mist-CVD
(2009-11-30)
Chaisitsak, S.
In this paper, a novel and simple method for synthesis of iron nanoparticles using a CVD of ferrocene-ethanol mist was proposed. By using this technique, graphite-encapsulated Fe2O3 nanoparticles could be synthesized at a low temperature of ∼400°C under 1 atm. The synthesis temperature as well as the deposition position and time were found to determine the amount of carbon-filament impurities in the obtained materials. The addition of water mist in the growth atmosphere was found to be a key parameter for eliminating carbon by-products due to the water-asisted etching effect. The result of this study could be useful for the production of graphite-encapsulated iron particles since our modified CVD technique is simple and low-cost. © 2009 American Institute of Physics.
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Effect of the deposition condition for carbon nanotube thin films on gas sensing performance
(2008-01-01)
Chaisitsak, S.
;
Tuantranont, A.
A simple fabrication process for single-walled carbon nanotube (SWCNT)-based sensors was reported. By using chemical vapor deposition (CVD) of alcohol-ferrocene mist, SWCNT films could be directly deposited on patterned Al electrodes to fabricate a sensor. The effects of depositing position along the inner quartz reactor on the properties of SWGNT films (morphology, structure and purity) and the characteristics of sensors (response and reproducibility) were investigated. The SWCNT-film-based sensors fabricated at low substrate temperatures of 200-700 °C exhibited a reasonably good sensitivity to saturated organic vapor (ethanol, methanol and acetone) and showed a fair reproducibility even operated at a room temperature (∼28 °C). Copyright © 2008 American Scientific Publishers All rights reserved.
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Parametric study of atmospheric-pressure single-walled carbon nanotubes growth by ferrocene-ethanol mist CVD
(2007-11-01)
Chaisitsak, S.
;
Nukeaw, J.
;
Tuantranont, A.
Uniform web-like films consisting single-walled carbon nanotubes (SWCNTs) were deposited on a silicon substrate using the chemical vapor deposition (CVD) of ferrocene-ethanol mist at atmospheric pressure (∼ 1 atm). The tiny mist was generated using a high-frequency ultrasonic vibration. The effects of various parameters including deposition position in the reactor, temperature, ferrocene/ethanol ratio, flow rate of carrier gas (argon), and deposition time on the formation of SWCNTs was investigated using high-resolution scanning electron microscopy, transmission electron microscopy and Raman spectroscopy. The worm region outside the furnace was found to be a suitable position for the formation of SWCNT films. The furnace temperature and the flow rate of carrier gas were found to determine the diameter and crystallinity of nanotube. The ferrocene concentration in ethanol strongly influenced the amount of impurity particles in the material. Moreover, the intensity of metallic tail in D-band was found to decrease with increasing the flow rate, showing a possibility of the formation of semiconducting SWCNTs. Results of this study can be used to improve understanding of the growth of SWCNTs by floating catalyst CVD of alcohol mist. © 2007 Elsevier B.V. All rights reserved.

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