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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 m<sup>2</sup> g<sup>-1</sup> 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<sup>-1</sup> with a capacitance retention of 62% when the current density increased to 1.5 A g<sup>-1</sup>. 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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    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
    ;
    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 m<sup>2</sup> g<sup>-1</sup>), total pore volume (1.37 cm<sup>3</sup> g<sup>-1</sup>) and nitrogen content (4.6 at%). Moreover, SD-ACs exhibited enhanced electrochemical properties with specific gravimetric and volumetric capacitances of 179 F g<sup>-1</sup> and 88 F cm<sup>-3</sup> in an organic electrolyte, respectively, a high capacitance retention of approximately 87% at a current density of 0.5 A g<sup>-1</sup> and excellent cycling stability of 97.5% after 3000 cycles at a current density of 5 A g<sup>-1</sup>. 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<sup>-1</sup>. 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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    Item type:Publication,
    Preparation of activated carbon via acidic dehydration of durian husk for supercapacitor applications
    (2020-08-01)
    Ukkakimapan, Pundita
    ;
    Sattayarut, Vichuda
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    Wanchaem, Thanthamrong
    ;
    Yordsri, Visittapong
    ;
    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 m<sup>2</sup>/g) and total pore volume (1.27 cm<sup>3</sup>/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/cm<sup>3</sup> 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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    Effect of Carbonization Temperature on Physical Properties and Specific Capacitance of Activated Carbon Derived from Banana Stem and Its Application as Supercapacitor Electrodes
    (2023-01-01)
    Dulyaseree, Paweena
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    Sama, Hasanee
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    Sada, Suraida
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    Ukkakimapan, Pundita
    ;
    Yordsri, Visittapong
    In this work, activated carbons (ACs) for electrodes supercapacitor applications were successfully synthesized from banana stem. Banana is one of the popular fruits that is easy to grow and most parts of the plant can be used. However, banana cultivation generates a lot of wastes, especially from the stem. Thus, using banana stem as raw material for ACs was investigated. The synthesis of AC consisted of 2 processes; carbonization and activation. The advantage of a two-step synthesis was the low weight loss of charcoal. Firstly, the carbonization process was conducted by varying the temperature between 300-600°C, and then inorganic elements were removed by treatment with 1 M sulfuric acid. After that, activation was conducted at 720°C under an argon atmosphere. The electrochemical properties of banana stem-derived ACs (BCH-ACs) were studied using sodium sulfate as an electrolyte. The BCH-ACs carbonized at 400°C showed the highest performance with a specific capacitance of 55.45 Fg<sup>-1</sup>, an energy density of 7.70 Whkg<sup>-1</sup> and a power density of 133.94 Wkg-1. The highest specific capacitance of the BCH400-AC was likely due to the increase in the amount of oxygenated functional group, which facilitated the access of electrolyte ions into the electrode. These results suggest that banana stem can be used to synthesize ACs via carbonization at 400°C, and the ACs generated can be applied as electrode in supercapacitors.
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    Comparison of acid exfoliators in carbon nanosheets synthesis from stinging nettle (Urtica dioica) for electrochemical applications
    (2020-12-01)
    Nuilek, Kanokon
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    Sattayarut, Vichuda
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    Simon, Andrea
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    Koncz-Horváth, Daniel
    Carbon nanosheets (CNs) were successfully synthesized from nettle stem (NS) which is an inexpensive material with a high carbon content that is abundantly available in nature. CNs were produced using chemical (potassium hydroxide activation and acid exfoliation) and thermal treatments. Sulfuric (H<inf>2</inf>SO<inf>4</inf>), phosphoric (H<inf>3</inf>PO<inf>4</inf>) and nitric (HNO<inf>3</inf>) acid solutions were used for exfoliation. CNs exfoliated by H<inf>3</inf>PO<inf>4</inf> have higher specific surface area (789 m<sup>2</sup> g<sup>−1</sup>) compared to CNs exfoliated by H<inf>2</inf>SO<inf>4</inf> (705 m<sup>2</sup> g<sup>−1</sup>) and HNO<inf>3</inf> (106 m<sup>2</sup> g<sup>−1</sup>). In this work, NSCNs were found to be a potential candidate for electrode material in electrochemical capacitors. The maximum specific capacitance of the NSCNs exfoliated by H<inf>3</inf>PO<inf>4</inf> is found to be 27.3 F g<sup>−1</sup> at a current density of 0.05 A g<sup>−1</sup>, while the specific capacitance of NSCNs exfoliated by H<inf>2</inf>SO<inf>4</inf> and HNO<inf>3</inf> is 9.34 F g<sup>−1</sup> and 1.71 F g<sup>−1</sup>, respectively. Energy density (0.06–0.95 Wh kg<sup>−1</sup>) and power density (20.9–26.7 W kg<sup>−1</sup>) of NSCNs are confirmed to be supercapacitor materials and can be applied in energy storage devices.
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    Item type:Publication,
    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 m<sup>2</sup> g<sup>-1</sup>, 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<sup>-1</sup> 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<sup>-1</sup> 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.