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Preparation of activated carbon via acidic dehydration of durian husk for supercapacitor applications
(2020-08-01)
Ukkakimapan, Pundita
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Sattayarut, Vichuda
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Wanchaem, Thanthamrong
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Yordsri, Visittapong
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Phonyiem, Mayuree
In this study, the preparation of activated carbons (ACs) via acidic dehydration of durian husk (DH) for supercapacitor application was investigated. The DH was dehydrated using sulfuric acid and subsequently activated by using sodium hydroxide as chemical reagent at 720 °C to obtain activated carbon (hereinafter referred to as DA). Surpassing the commercial ACs and the ACs derived from the conventional carbonization and activation (hereinafter referred to as CA), the DA exhibited superior properties in high surface area (2578 m2/g) and total pore volume (1.27 cm3/g). Moreover, besides carbon and oxygen, the DA contained sulfur and nitrogen in the carbon network. The DA can act as a suitable material for supercapacitor electrode with the specific gravimetric and volumetric capacitances of 145 F/g and 70 F/cm3 in an organic electrolyte. The device also showed a promising performance with an energy density of 32 Wh/kg and a power density of 316 W/kg. These results demonstrate that the preparation of ACs via acidic dehydration of DH offers the advantages in terms of simplicity, low cost, and short-time processing to achieve heteroatom self-doped ACs with a high surface area for high-performance supercapacitors.
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Investigation on electrochemical properties of sugarcane leaves-derived activated carbon by steam activation
(2020-01-01)
Ukkakimapan, Pundita
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Ukakimaparn, Prapart
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Wanchaem, Thanthamrong
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Yordsri, Visittapong
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Sattayarut, Vichuda
Sugarcane leaves (SLs) are a bio-waste from sugar production industry. To explore the value-added SLs, the SLs were used raw materials of activated carbons (ACs) by steam activation and their electrochemial properties were investigated for supercapacitor applications. The synthesis of ACs from the SLs consisted of two steps; carbonization at 500ºC and steam activation. The synthesis condition was optimized by varying activation temperature (800 and 850ºC) The porous structures were thoroughly formed on the surface after steam activation and the surface areas were reached to 630 and 639 m2 g-1 at the activation temperature of 800 and 850ºC, respectively. The SLs-derived ACs activated at 800ºC assembled in coin cell using organic electrolyte showed the highest specific capacitance of approximately 16 F g-1 with a capacitance retention of 62% when the current density increased to 1.5 A g-1. Even though there is a room to improve the electrochemical properties such as optimization of porosity and removal of inorganic component, the SLs show a potential use as raw materials of ACs for supercapacitor applications.
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Preparation and electrochemical performance of nitrogen-enriched activated carbon derived from silkworm pupae waste
(2019-01-01)
Sattayarut, Vichuda
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Chanthad, Chalathorn
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Khemthong, Pongtanawat
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Kuboon, Sanchai
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Wanchaem, Thanthamrong
In this study, nitrogen-enriched activated carbon from silkworm pupae waste (P-AC) was successfully prepared and its electrochemical performances in aqueous and organic electrolytes were investigated. Silkworm pupae waste is beneficial because it is a nitrogen-enriched, inexpensive, and locally available material. The preparation process includes hydrothermal treatment of the silkworm pupae waste at 200 °C, and chemical activation using zinc chloride at activation temperatures of 700, 800 and 900 °C (P700, P800, and P900, respectively). The nitrogen content in the P-ACs was approximately 3.8-6.4 at%, decreasing with activation temperature, while the surface area was approximately 1062-1267 m2 g-1, increasing with activation temperature. Compared to a commercial AC, the P-ACs show higher nitrogen content but lower surface area. Furthermore, the P800 exhibited superior specific capacitance (154.6 and 91.6 F g-1 in aqueous and organic electrolytes) compared to a commercial AC despite possessing smaller surface area. The high nitrogen content enhanced the pseudocapacitance and improved the electrical conductivity of the P-ACs. These properties were confirmed by relatively low series and charge transfer resistances, a capacity retention higher than 88% at a current density of 0.5 A g-1 and excellent cycling stability demonstrated by maintaining 97.6% of its capacitance after 3000 cycles. These results demonstrate that silkworm pupae waste is a viable source of nitrogen-enriched AC for application in supercapacitors.
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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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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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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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Nitrogen-rich green leaves of papaya and: Coccinia grandis as precursors of activated carbon and their electrochemical properties
(2017-01-01)
Dulyaseree, Paweena
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Fujishige, Masatsugu
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Yoshida, Ichiro
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Toya, Yumiko
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Banba, Yasuo
Activated carbon (AC) was synthesized from papaya and Coccinia grandis leaves (PL-AC and CL-AC, respectively) which are nitrogen-rich precursors and their electrochemical properties were investigated. The synthesis process included carbonization at 400 °C, impurity removal by H<inf>2</inf>SO<inf>4</inf> cleaning, and post activation by NaOH at 720 °C. Surpassing the conventional bamboo-derived AC (B-AC), PL- and CL-ACs show relatively high surface areas of 2664 and 2576 m2 g-1, respectively. Moreover, the nitrogen contents in the PL- and CL-ACs were approximately 2.3 and 1.8 at%, respectively. Furthermore, the electrochemical properties of the synthesized PL- and CL-ACs were investigated using both aqueous and organic electrolytes. The specific capacitances of the PL- and CL-ACs were 98.47 and 89.91 F g-1, respectively, in Na<inf>2</inf>SO<inf>4</inf> electrolyte. Especially, compared to the B-AC, the PL-AC shows a dramatic decrease in series resistances (R<inf>S</inf>) from 1.33 to 0.53 Ω and charge transfer resistances (R<inf>CT</inf>) from 25.83 to 9.00 Ω. The decrease of R<inf>S</inf> and R<inf>CT</inf> is attributed to the existence of nitrogen in the PL-AC, resulting in a higher conductivity of electrode material and an enhancement of the charge transfer between electrode material and electrolyte. The large surface area of the PL- and CL-ACs was successfully achieved without detriment to the electrical conductivity. These results suggest that nitrogen-rich PL and CL are potential precursors for the synthesis of nitrogen-doped AC in a one-step process, which can be used as an alternative electrode material for electrochemical capacitors and can potentially be applied for large-scale industrial production with low cost.

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