Wongwiriyapan, Winadda

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Wongwiriyapan, W.

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Integrated Innovative Technology

winadda.wo@kmitl.ac.th

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Hybrid gas sensor based on platinum nanoparticles/poly(methyl methacrylate)-coated single-walled carbon nanotubes for dichloromethane detection with a high response magnitude
(2016-05-01)
Muangrat, Worawut
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Yordsri, Visittapong
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Maolanon, Rungroj
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Pratontep, Sirapat
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Porntheeraphat, Supanit
A dichloromethane (DCM) sensor with a high response magnitude was successfully fabricated using the integration of single-walled carbon nanotubes (SWNTs), poly(methyl methacrylate) (PMMA) and platinum nanoparticles (Pt NPs). A pristine SWNT network was first formed by drop-casting onto printed circuit board (PCB) substrates. Next, PMMA was coated onto the pre-dropped SWNT network by spin coating using a PMMA-toluene solution, followed by the deposition of Pt NPs by electron-beam evaporation (hereafter referred to as Pt/PMMA/SWNT). The Pt/PMMA/SWNT enabled an approximately 69-fold improvement in DCM detection compared to pristine SWNT. The high response magnitude of the Pt/PMMA/SWNT was successfully achieved because of the incorporation of PMMA and Pt functions. Swelling of the PMMA matrix as a result of DCM adsorption leads to PMMA volume expansion, thereby increasing the SWNT-SWNT distance, which results in an increase in the resistance. Pt NPs promote the dissociation of DCM to CO, and consequently the CO oxidation on the Pt NPs catalyst and electron donation from Pt NPs to SWNTs, resulting in an increase in the resistance. Moreover, a linear relationship was obtained between the sensor response of the Pt/PMMA/SWNT and the concentration of DCM. These results suggest that the integration of SWNTs with PMMA and Pt NPs is a promising approach for improving DCM detection at room temperature.
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Field emission properties of a DWCNT bundle and a single MWCNT
(2018-02-01)
Fujishige, Masatsugu
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Wongwiriyapan, Winadda
;
Muramatsu, Hiroyuki
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Takeuchi, Kenji
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Arai, Susumu
The field emission properties of a bundle of double-walled carbon nanotubes (DWCNTs) and a single multiwalled carbon nanotube (MWCNT) were investigated. A DWCNT bundle or a single MWCNT was attached to the head of sharpened tip of tungsten by electrophoresis; the tungsten tip was dipped into a drop of a carbon nanotube/1,2-dichloroethane suspension on a stainless plate, and a high-frequency AC voltage (20 V peak to peak with a frequency of 15 MHz) was applied between the tungsten tip and the stainless steel plate. The turn-on fields of the DWCNT and MWCNT tips for 1 nA/cm2 were 0.05 and 0.48 V/μm, respectively. From the Fowler-Nordheim plots, the field enhancement factor (β) of the tips was estimated to be 109,600 (DWCNT) and 6780 (MWCNT). The present DWCNT emitter is characterized by a very small turn-on field and large β. The field emission performance is discussed in terms of the sizes of the bundle of DWCNTs and a single MWCNT.
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Hydrogen sensing properties of protective-layer-coated single-walled carbon nanotubes with palladium nanoparticle decoration
(2011-02-04)
Wongwiriyapan, W.
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Okabayashi, Y.
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Minami, S.
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Itabashi, K.
;
Ueda, T.
Protective-layer-coated single-walled carbon nanotubes (SWNTs) with palladium nanoparticle decoration (Pd-SiO<inf>2</inf>-SWNTs) were fabricated and their sensing properties for hydrogen (H<inf>2</inf>) were investigated. SWNTs were coated with a 3-4 nm thick SiO<inf>2</inf> layer by pulsed laser deposition and subsequently decorated with Pd nanoparticles by electron beam evaporation. Even though the SWNTs were completely surrounded by a protective layer, Pd-SiO<inf>2</inf>-SWNTs responded to H<inf>2</inf> down to a concentration of 1 part per million. Compared with the Pd nanoparticle-decorated SWNTs without a protective layer (Pd-SWNTs), Pd-SiO<inf>2</inf>-SWNTs exhibited highly stable sensor responses with variations of less than 20%; Pd-SWNTs showed a variation of 80%. The density of the Pd-SWNTs significantly decreased after the sensing test, while that of the Pd-SiO<inf>2</inf>-SWNTs with the netlike structure remained unchanged. The hydrogen sensing mechanism of the Pd-SiO <inf>2</inf>-SWNTs was attributed to the chemical gating effect on the SWNTs due to dipole layer formation by hydrogen atoms trapped at the Pd-SiO<inf>2</inf> interface. Moreover, the relationship between H<inf>2</inf> concentration and sensor response can be described by the Langmuir isotherm for dissociative adsorption. © 2011 IOP Publishing Ltd.
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Effect of metal catalysts on synthesis of carbon nanomaterials by alcohol catalytic chemical vapor deposition
(2013-12-31)
Muangrat, Worawut
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Porntheeraphat, Supanit
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Wongwiriyapan, Winadda
Carbon nanomaterials (CNMs) were synthesized by alcohol catalytic chemical vapor deposition (CVD) at atmospheric pressure using different metal catalysts (Ni, Co and Fe) at a growth temperature of 700°C. Ni and Fe acted as active catalysts for multi-walled carbon nanotubes (MWNTs) growth, while Co acted as an active catalyst for bamboo-like MWNTs and carbon nanofibers (CNFs) growth. The CNMs synthesized from Ni catalyst showed the highest crystallinity with a small amount of by-products. These results imply that metal catalyst is a key parameter to the structure, morphology and crystallinity of CNMs. The different effects of metal catalysts on the growth of CNMs can be explained in terms of the difference in the change in Gibbs free energy of metal carbide formation.
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Multifunctional Solvent Molecule Realizing High-Performance Elastic Polymer Electrolytes for Lithium Metal Batteries
(2025-11-26)
Nipatwarakan, Pimchanok
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Song, Junlin
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Cui, Yujie
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Guo, Decai
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Song, Yongyi
Solid-state polyurethane electrolytes offer excellent elasticity, which can significantly improve the interfacial ion transport of solid-state lithium metal batteries. However, pure polyurethane electrolytes suffer from poor Li+ conductivity. Herein, a multifunctional solvent molecule, trifluoro-N,N-dimethylacetamide (TFDMA), is introduced to modify the thermoplastic polyurethane (TPU) electrolyte, resulting in a composite electrolyte (TPU-TFDMA) with both high mechanical properties and good Li+ transport performance (ionic conductivity = 1.53 × 10–3 S cm–1 and Li+ transference number = 0.50). Experimental characterizations and theoretical simulations reveal that the presence of additional hydrogen-bonding interactions between TFDMA and the TPU chains not only maintains the mechanical strength of TPU but also enhances interfacial stability and effectively inhibits lithium dendrite growth. Furthermore, TFDMA promotes lithium salt dissociation and reduces the coordination between solvent molecules and Li+, facilitating Li+ desolvation and rapid diffusion. TFDMA also immobilizes TFSI–, thereby enhancing Li+ transport efficiency and contributing to the formation of stable and multifunctional interfaces between electrodes and electrolytes. Consequently, the TPU-TFDMA electrolytes enable the Li symmetric cell to stably work for over 2500 h and endow the LiFePO<inf>4</inf> full cell with a reversible capacity of 130 mAh g–1 after 320 cycles at 0.5 C.
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Adsorption kinetics of NO2 on single-walled carbon nanotube thin-film sensor
(2008-10-01)
Wongwiriyapan, Winadda
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Inoue, Satoshi
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Honda, Shin ichi
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Katayama, Mitsuhiro
The adsorption kinetics of NO<inf>2</inf> on a single-walled carbon nanotube (SWNT) thin-film sensor was investigated. To avoid the influence of ambient air, the adsorption property of SWNTs was explored under high vacuum. By virtue of the suppression of the influence of residual gases and the cleanness of the SWNT surface in vacuum, the SWNTs exhibited high sensitivity with a detection limit of lower than 1 ppb. On the basis of the Langmuir adsorption isotherm, the sticking probability and adsorption energy of NO<inf>2</inf> molecules on SWNTs were experimentally estimated. © 2008 The Japan Society of Applied Physics.
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A flexible formaldehyde sensor based on palladium nanoparticles-polyvinylpyrrolidone-carbon nanotubes-nanocellulose composite films
(2025-01-01)
Chobsilp, Thanattha
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Muangrat, Worawut
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Inpaeng, Saowaluk
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Tedsree, Karaked
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Yordsri, Visittapong
A flexible formaldehyde sensor with high sensitivity was successfully fabricated by integrating palladium (Pd) nanoparticles, polyvinylpyrrolidone (PVP), multi-walled carbon nanotubes (MWCNTs) and nanocellulose (NC) into composite films. The flexible composite films were fabricated via vacuum filtration. The morphology, structure, composition, crystallinity, and functional group of as-fabricated sensing materials were characterized by scanning electron microscopy, transmission electron microscopy, electron probe microanalyzer, Raman spectroscopy, and Fourier transform infrared spectrometer. Pd nanoparticles-PVP-MWCNTs-NC (Pd-PVP-MWCNTs-NC) composite films exhibited an 11-fold increase in formaldehyde sensitivity compared to MWCNTs-NC composite films. The excellent sensing performances of Pd-PVP-MWCNTs-NC sensors were attributed to the combination of Pd nanoparticles and PVP. The enhanced sensitivity is attributed to the synergistic effect of the high electron transfer from formaldehyde molecule to Pd nanoparticles and swelling of PVP due to sorption of formaldehyde molecule. Pd-PVP-MWCNTs-NC sensors still maintained good response under bending angle up to 30° and 300 bending cycles. The results demonstrate that the Pd-PVP-MWCNTs-NC composite films are highly promising in terms of sensitivity and flexibility for sub-ppm level formaldehyde detection at room temperature.
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Carbon nanotube/polydimethylsiloxane composite micropillar arrays using non-lithographic silicon nanowires as a template for performance enhancement of triboelectric nanogenerators
(2021-02-26)
Pinming, Chinathun
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Wongwiriyapan, Winadda
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Rattanamai, Songsak
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Ketama, Nathakreat
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Treetong, Alongkot
Carbon nanotube/polydimethylsiloxane composite micropillar (CNT/PDMS MP) arrays were successfully fabricated using non-lithographic silicon nanowire (SiNW) arrays as a template for performance enhancement of triboelectric nanogenerators (TENG). The CNT/PDMS MP arrays were obtained by pouring CNT/PDMS composites on the SiNW arrays and peeled off. Surface topology of CNT/PDMS composites directly depends on morphology of SiNW arrays, which can be varied by the etching time of the typical metal-assisted chemical etching process. The micropatterned CNT/PDMS composites was mostly depicted to the SiNW array template pattern when the morphologies of the SiNW were optimized with a length of approximately 10 mm. Next, the CNT/PDMS MP arrays were utilized as a triboelectric layer of TENGs, generating the maximum output voltage of 22.84 0.85 V, enabling an approximately 18-fold improvement in an electrical output compared to the flat PDMS-based TENG. The performance enhancement of TENGs based on CNT/PDMS MP arrays are attributed to synergic effects of (1) an enhancement of electrostatic induction by CNT composites, increasing dielectric constant, and (2) an enhancement of electrification by surface texturing using non-lithographic pattern and CNT composites.
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Nitrogen self-doped activated carbons: Via the direct activation of Samanea saman leaves for high energy density supercapacitors
(2019-01-01)
Sattayarut, Vichuda
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Wanchaem, Thanthamrong
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Ukkakimapan, Pundita
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Yordsri, Visittapong
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Dulyaseree, Paweena
In this study, nitrogen self-doped activated carbons (ACs) obtained via the direct activation of Samanea saman green leaves (SSLs) for high energy density supercapacitors were investigated. The SSL-derived direct-activated carbons (hereinafter referred to SD-ACs) were synthesized by impregnating sodium hydroxide as an activating agent and heating up to 720 °C without a hydrothermal carbonization or pyrolysis step. The optimum condition was investigated by varying the weight ratio of raw SSLs to NaOH. Surpassing the ACs derived from the two-step convention method, SD-ACs showed superior properties, including a higher surface area (2930 m2 g-1), total pore volume (1.37 cm3 g-1) and nitrogen content (4.6 at%). Moreover, SD-ACs exhibited enhanced electrochemical properties with specific gravimetric and volumetric capacitances of 179 F g-1 and 88 F cm-3 in an organic electrolyte, respectively, a high capacitance retention of approximately 87% at a current density of 0.5 A g-1 and excellent cycling stability of 97.5% after 3000 cycles at a current density of 5 A g-1. Moreover, the potential window of the supercapacitor cell was extended to 3.5 V with a significantly enhanced energy density of up to 79 W h kg-1. These results demonstrate that the direct activation of nitrogen-enriched SSLs offers advantages in terms of simplicity, low-cost and sustainable synthetic route to achieve nitrogen self-doped ACs for high energy density supercapacitors, which exhibit superior properties to that of ACs prepared via the conventional method.
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Hydrothermal Synthesis of MnO2 and Hemp-Derived Activated Carbon Composites for Tailored Electrochemical Performance
(2026-07-22)
Klangvijit, Kanisorn
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Bowornthommatadsana, Khemjiranee
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Reilly, Mayuree Phonyiem
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Obata, Michiko
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Fujishige, Masatsugu
This study investigates hydrothermal synthesis of manganese dioxide composited with hemp-derived activated carbon (MnO<inf>2</inf>/AC) as electrodes for supercapacitors. The effects of key hydrothermal parameters, including carbon ratio, reaction temperature, and reaction time were systematically examined. Phase-pure α-MnO<inf>2</inf> was uniformly anchored on carbon framework. Morphology of MnO<inf>2</inf> evolved from nanowalls to well-defined nanorods with increasing reaction temperature and time. Meanwhile, the specific surface area of MnO<inf>2</inf>/AC decreased from 1712 to 1538 m2 g−1 due to partial pore blocking, while a predominantly mesoporous structure was retained. Electrochemical measurements in 1 M Na<inf>2</inf>SO<inf>4</inf> demonstrate that the optimized MnO<inf>2</inf>/AC composites achieve a specific capacitance of 216.8 F g−1 at 1 A g−1. Charge-storage mechanism analysis reveals a balanced contribution between surface-controlled capacitive processes and diffusion-controlled pseudocapacitance, which is directly correlated with preserved mesoporosity and moderate MnO<inf>2</inf> coverage. When the MnO<inf>2</inf>/AC composites were assembled into an asymmetric supercapacitor using AC as the negative electrode, the device operates stably up to 2.4 V and delivers outstanding cycling stability over 95% after 22,000 charge–discharge cycles at 5 A g−1. These results demonstrate that controlled growth of MnO<inf>2</inf>, rather than maximum oxide loading, is essential for optimizing charge-storage mechanisms and achieving high-performance biomass-derived supercapacitor electrodes.

Wongwiriyapan, Winadda

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