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Surface Modification of Activated Carbon by Nitrogen Doping and KOH Activation for Enhanced Carbon Dioxide Adsorption Performance
(2025-01-01)
Chobsilp, Thanattha
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Treetong, Alongkot
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Yordsri, Visittapong
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Santasnachok, Mattana
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Charoeythornkhajhornchai, Pollawat
Nitrogen-doped activated carbon (N-AC) was successfully prepared by KOH-activation and nitrogen doping using ammonia (NH<inf>3</inf>) heat treatment. Coconut shell-derived activated carbon (AC) was heat-treated under NH<inf>3</inf> gas in the temperature range of 700℃–900℃. Likewise, the mixture of potassium hydroxide (KOH) and AC was heated at 800℃, followed by heat treatment under NH<inf>3</inf> gas at 800℃ (hereafter referred to as KOH-N-AC800). Scanning electron microscopy (SEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and Brunauer-Emmett-Teller (BET) method were utilized to analyze morphology, crystallinity, chemical bonding, chemical composition and surface area. The surface area and porosity of N-AC increased with increasing NH<inf>3</inf> heat treatment. Similarly, the nitrogen content in the N-AC increased from 3.23% to 4.84 at% when the NH<inf>3</inf> heat treatment was raised from 700℃ to 800℃. However, the nitrogen content of N-AC decreased to 3.40 at% after using NH<inf>3</inf> heat treatment at 900℃. The nitrogen content of KOH-N-AC800 is 5.43 at%. KOH-N-AC800 and N-AC800 exhibited improvements of 33.66% and 26.24%, respectively, in CO<inf>2</inf> adsorption compared with AC. The enhancement of CO<inf>2</inf> adsorption of KOH-N-AC800 is attributed to the synergic effect of the nitrogen doping, high surface area, and porosity. The results exhibited that nitrogen sites on the surface play a more significant role in CO<inf>2</inf> adsorption than surface area and porosity. This work proposes the potential synergistic effect of KOH-activation and nitrogen doping for enhancing the CO<inf>2</inf> adsorption capacity of activated carbon.
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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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Nitrogen-doped graphene nanosheet-double-walled carbon nanotube hybrid nanostructures for high-performance supercapacitors
(2021-09-01)
Muangrat, Worawut
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Obata, Michiko
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Htay, Myo Than
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Fujishige, Masatsugu
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Dulyaseree, Paweena
A hybrid nitrogen-doped graphene nanosheet-grafted double-walled carbon nanotube (NG-DWCNT) was synthesized by chemical vapor deposition (CVD). Double-walled carbon nanotube (DWCNT) was synthesized by floating catalytic CVD using ferrocene and thiophene dissolved in ethanol. NG was directly grafted onto the DWCNT bundles by thermal CVD using mixed ethanol-urea solution. The NG possess sharp-edged petal-like structure on one-dimensional DWCNT bundle. The NG-DWCNT showed the nitrogen content of approximately 1.93 at%. The NG-DWCNT hybrid nanostructures exhibited a higher specific capacitance of 563 F g<sup>−1</sup> than that of the DWCNT and un-doped G-DWCNT. The improvement of capacitance value is attributed to the synergic effect of the nitrogen doping together with the sharp-edged petal-like structure of the NG. The facile technique by CVD method provides a promising approach for simple and low-cost technique to synthesize the NG-DWCNT hybrid nanostructures. A hybrid carbon nanostructure of NG-DWCNT has a potential application in electrochemical conversion and energy storage devices.
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Graphene nanosheet-grafted double-walled carbon nanotube hybrid nanostructures by two-step chemical vapor deposition and their application for ethanol detection
(2019-12-01)
Muangrat, Worawut
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Wongwiriyapan, Winadda
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Morimoto, Shingo
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Hashimoto, Yoshio
Here, we present a facile technique for synthesis of graphene nanosheet (GNS)-grafted double-walled carbon nanotube (DWCNT) hybrid carbon nanostructures (here after referred to as G-DWCNTs) by directly growing GNSs along the sidewalls of DWCNTs using a two-step chemical vapor deposition (CVD). DWCNTs were synthesized by floating catalyst CVD at 1300 °C using ferrocene and thiophene dissolved in ethanol. Then, GNSs were grafted onto the synthesized DWCNT bundles by thermal CVD at 1300 °C using ethanol. The sharp-edged petal-like structure of GNSs were grown along the sidewalls of DWCNT bundles while maintaining the one-dimensional structure of DWCNT. Next, DWCNTs and G-DWCNTs were dispersed in ethanol, then deposited on the paper using vacuum filtration method and used for ethanol detection. G-DWCNTs sensor exhibited a 3-fold improvement in the response to ethanol vapor compared to the DWCNTs sensor. The sensing mechanism of DWCNTs and G-DWCNTs can be described in terms of charge transfer between the gas molecules and sensing material. These results demonstrate that the facile technique by two-step CVD method provides a promising approach for simple and low-cost technique to synthesize the hybrid nanostructure of GNSs and DWCNTs. The new hybrid carbon nanostructures are attractive for gas sensing application.
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Unravel the Active Site in Nitrogen-Doped Double-Walled Carbon Nanotubes for Nitrogen Dioxide Gas Sensor
(2018-07-11)
Muangrat, Worawut
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Wongwiriyapan, Winadda
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Yordsri, Visittapong
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Chobsilp, Thanattha
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Inpaeng, Saowaluk
In this paper, a nitrogen dioxide (NO<inf>2</inf>) gas sensor using nitrogen-doped double-walled carbon nanotubes (N-DWCNTs) with different types of nitrogen is demonstrated, and the sensor performance to the pyridinic nitrogen is related. The ratio of nitrogen is controlled by the temperature applied for the synthesis. It is found that the fabricated sensor from N-DWCNTs enable an approximately threefold improvement in NO<inf>2</inf> detection compared to the sensor from DWCNTs. Also, the improvement of sensor response of N-DWCNTs more depends on the pyridinic site than the other types of nitrogen, because it can strongly interact with the NO<inf>2</inf> molecule. The sensing mechanism is attributed to the charge transfer between the NO<inf>2</inf> molecule and the sensing materials (especially with pyridinic site), which shifts the Fermi level, resulting in a decrease of the electrical resistance. Furthermore, the relation between the sensor response and the concentration of NO<inf>2</inf> is derived based on Langmuir adsorption isotherm, and the calculated detection limit can be down to 0.14 ppm, which suggests that the N-DWCNTs-based sensor is a promising approach for low concentration NO<inf>2</inf> detection at room temperature.
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Graphene and poly(methyl methacrylate) composite laminates on flexible substrates for volatile organic compound detection
(2018-04-01)
Rattanabut, Chanoknan
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Wongwiriyapan, Winadda
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Muangrat, Worawut
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Bunjongpru, Win
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Phonyiem, Mayuree
In this paper, we present a gas sensor for volatile organic compound (VOC) detection based on graphene and poly(methyl methacrylate) (GR/PMMA) composite laminates fabricated using CVD-grown graphene. Graphene was transferred to a poly(ethylene terephthalate) (PET) substrate by PMMA-supported wet transfer process without PMMA removal in order to achieve the deposition of GR/PMMA composite laminates on PET. The GR/PMMA and graphene sensors show completely different sensitivities to VOC vapors. The GR/PMMA and graphene sensors showed the highest sensitivities to dichloromethane (DCM). The response of the GR/PMMA sensor to DCM was 3 times higher than that of the graphene sensor but the GR/PMMA sensor hardly responded to acetone, chloroform, or benzene. The sensing mechanism of the graphene sensor can be based on the dielectric constant of VOCs, the size of VOC molecule, and electron hopping effects on defect graphene, while that of the GR/PMMA sensor can be explained in terms of the polymer swelling owing to the Hansen solubility parameter.
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Graphene and poly(methyl methacrylate) composite laminates on flexible substrates for volatile organic compound detection
(2018-04-01)
Rattanabut, Chanoknan
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Wongwiriyapan, Winadda
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Muangrat, Worawut
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Bunjongpru, Win
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Phonyiem, Mayuree
In this paper, we present a gas sensor for volatile organic compound (VOC) detection based on graphene and poly(methyl methacrylate) (GR/PMMA) composite laminates fabricated using CVD-grown graphene. Graphene was transferred to a poly(ethylene terephthalate) (PET) substrate by PMMA-supported wet transfer process without PMMA removal in order to achieve the deposition of GR/PMMA composite laminates on PET. The GR/PMMA and graphene sensors show completely different sensitivities to VOC vapors. The GR/PMMA and graphene sensors showed the highest sensitivities to dichloromethane (DCM). The response of the GR/PMMA sensor to DCM was 3 times higher than that of the graphene sensor but the GR/PMMA sensor hardly responded to acetone, chloroform, or benzene. The sensing mechanism of the graphene sensor can be based on the dielectric constant of VOCs, the size of VOC molecule, and electron hopping effects on defect graphene, while that of the GR/PMMA sensor can be explained in terms of the polymer swelling owing to the Hansen solubility parameter.
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Sensitivity Enhancement of Benzene Sensor Using Ethyl Cellulose-Coated Surface-Functionalized Carbon Nanotubes
(2018-01-01)
Chobsilp, Thanattha
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Muangrat, Worawut
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Issro, Chaisak
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Chaiwat, Weerawut
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Eiad-Ua, Apiluck
A hybrid sensor based on the integration of functionalized multiwalled carbon nanotubes (MWCNTs) with ethyl cellulose (EC) was fabricated for sensitivity enhancement of benzene detection. To functionalize the surface of MWCNTs, MWCNTs were treated with hydrochloric acid for 60 min (A60-MWCNTs), while other MWCNTs were treated with oxygen plasma for 30, 60, 90, and 120 min (P30-MWCNTs, P60-MWCNTs, P90-MWCNTs, and P120-MWCNTs, resp.). Pristine MWCNTs, A-MWCNTs, and P-MWCNTs were dispersed in 1,2-dichloroethane, then dropped onto a printed circuit board consisting of Cu/Au electrodes used as the sensor platform. Next, EC was separately spin coated on the pristine MWCNTs, A-MWCNTs, and P-MWCNTs (EC/MWCNTs, EC/A-MWCNTs, and EC/P-MWCNTs, resp.). All sensors responded to benzene vapor at room temperature by increasing their electrical resistance which was sensitive to benzene vapor. The EC/P90-MWCNTs enabled an approximately 11-fold improvement in benzene detection compared to EC/MWCNTs. The sensitivity of all sensors would be attributed to the swelling of EC, resulting in the loosening of the MWCNT network after benzene vapor exposure. The differences of the sensing responses of the EC/MWCNTs, EC/A-MWCNTs, and EC/P-MWCNTs would be ascribed to the differences in crystallinity and functionalization of MWCNT sidewalls, suggesting that acid and oxygen plasma treatments of MWCNTs would be promising techniques for the improvement of benzene detection.
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Hybrid graphene and poly(methyl methacrylate) for gas sensor application
(2017-01-01)
Rattanabut, Chanoknan
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Muangrat, Worawut
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Phonyiem, Mayuree
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Bungjongpru, Win
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Wongwiriyapan, Winadda
The graphene and hybrid graphene/poly(methy methacrylate) (PMMA) were fabricated for use in volatile organic compound (VOC) detection. Graphene was synthesized on copper foil by chemical vapor deposition (CVD). To remove Cu foil, PMMA was coated on graphene by spin-coating (hereafter referred to as graphene/PMMA) and transferred to silicon substrate with silicon dioxide layer (SiO<inf>2</inf>/Si) by wetting transfer process. For comparison, a PMMA layer was removed in order to achieve a pristine graphene. Graphene and hybrid graphene/PMMA sensors showed the highest sensor response to ethanol. Responses of the graphene to ethanol, dichloromethane and benzene were 5.62, 20.06 and 35.09 times higher than that of hybrid graphene/PMMA. The sensor response of graphene can be described in terms of the dielectric constant of VOC. In addition, the sensor response of hybrid graphene/PMMA to benzene and dichloromethane would be attributed to the Hansen solubility parameter (HSP), while that of ethanol is related to the molecular size. These results suggest that the integration of graphene with PMMA is a promising approach for the selectivity for VOC detection.
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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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