Browsing by Author "Chang, Pei-Yi"

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Boron Doped Graphene Quantum Structure and MoS2 Nanohybrid as Anode Materials for Highly Reversible Lithium Storage
(2019-03-13)
Riyanto
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Sahroni, Imam
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Bindumadhavan, Kartick
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Chang, Pei-Yi
;
Doong, Ruey-an
Herein, the boron-doped graphene quantum structure (BGQS), which contains both the advantages of 0-D graphene quantum dot and 2-D reduced graphene oxide, has been fabricated by top-down hydrothermal method and then mixed with molybdenum sulfide (MoS2) to serve as an active electrode material for the enhanced electrochemical performance of lithium ion battery. Results show that 30 wt% of BGQS/MoS2 nanohybrid delivers the superior electrochemical performance in comparison with other BGQS/MoS2 and bare components. A highly reversible capacity of 3,055 mAh g(-1) at a current density of 50mA g(-1) is achieved for the initial discharge and a high reversible capacity of 1,041 mAh g(-1) is obtained at 100mA g(-1) after 50 cycles. The improved electrochemical performance in BGQS/MoS2 nanohybrid is attributed to the well exfoliated MoS2 structures and the presence of BGQS, which can provide the vitally nano-dimensional contact for the enhanced electrochemical performance. Results obtained in this study clearly demonstrate that BGQS/MoS2 is a promising material for lithium ion battery and can open a pathway to fabricate novel 2-D nanosheeted nanocomposites for highly reversible Li storage application.
Electrochemical reactivity of carbonaceous materials for water treatment and energy recovery
(2018-03-18)
Doong, Ruey-An
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Chang, Pei-Yi
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Hsu, Chia-wen
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環境工程研究所
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Institute of Environmental Engineering
Microwave-assisted synthesis of SnO2/mesoporous carbon core-satellite microspheres as anode material for high-rate lithium ion batteries
(2019-02-15)
Chang, Pei-Yi
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Doong, Ruey-an
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環境工程研究所
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Institute of Environmental Engineering
The highly ordered microspheres containing ultrafine SnO2 nanoparticles and mesoporous carbon is fabricated using microwave-assisted hydrothermal method for high-rate and durable Li-ion battery application. The uniformly carbon nanosphere with an average diameter of around 90 nm exhibits large specific surface area and good mechanical stability to minimize the volume expansion of SnO2 during intercalation-deintercalation. The homogeneous coverage with 3-6 nm SnO2 nanoparticle provides sufficient active sites to facilitate the rapid lithiation-delithiation process through the fast ion transfer rates. Remarkably, SnO2/OMCS at Sn/C ratio of 35% exhibits an excellent initial capacity of 1770 mAh g(-1) at a current density of 35 mAg(-1) and can maintain at a stable capacity of 400 mAh g(-1) under an ultrahigh current density of 3500 mA g(-1) after 400 cycles. The intimate contact of SnO2 with ordered mesoporous carbon sphere shortens the electrons transport paths, resulting in the enhancement of stable lithium storage capacity at a high current density. Results obtained in this study clearly demonstrate that SnO2/OMCS nanocomposite is a promising material for lithium-ion battery and can provide an alternative to fabricate novel mesoporous carbon sphere-based nanocomposites for long cycle life and high-rate energy storage application. (C) 2018 Elsevier B.V. All rights reserved.
Silver nanoparticles embedded boron-doped reduced graphene oxide as anode material for high performance lithium ion battery
(2017-07-20)
Bindumadhavan, Kartick
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Chang, Pei-Yi
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Doong, Ruey-an
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環境工程研究所
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Institute of Environmental Engineering
Lithium ion batteries (LIBs) are important energy generation and storage devices and the development of anode materials can improve the electrochemical performance of LIBs. Herein, we report the fabrication of Ag nanoparticles embedded boron-doped reduced graphene oxide (Ag/B-rGO) with the addition of 10-30 wt% boric acid as anode materials for high performance LIB application. The combination of Ag nanoparticles with B-doped rGO enhances the reactivity of nanocomposites toward Li+ ions intercalation. The Ag/B-rGO nanocomposites with the addition of 30 wt% boric acid (Ag/B-rGO-30) exhibits significantly improved rate capability. The reversible capacity of 1484 mAh g(-1) at 50 mAg(-1) is initially observed and can retain at 430 mAh g(-1) when the current density increases to 1000 mAg(-1). In addition, the Ag/B-rGO exhibits the stable capacity of 540 mAh g(-1) at 100 mAg(-1) after 100 cycles of lithiation/delithiation process. The presence of doped boron improves the electron density and increases the defect sites, resulting in the acceleration of electron transfer rate through the graphitic network. In addition, the embedded Ag nanoparticles with diameters of 10-15 nm over 2-3 layered B-rGO decrease the internal resistance of Ag/B-rGO nanocomposites as well as improve the conductively nano-dimensional contacts for electron transport. Results obtained in this study clearly demonstrate the role of heteroatoms in the enhancement of electrochemical performance of lithiation capacity and can open a new route to fabricate metal-decorated rGO-based nanomaterials for high performance energy storage devices. (c) 2017 Elsevier Ltd. All rights reserved.
Size Effect of Ordered Mesoporous Carbon Nanospheres for Anodes in Li-Ion Battery
(2015-12-01)
Chang, Pei-Yi
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Bindumadhavan, Kartick
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Doong, Ruey-An
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環境工程研究所
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Institute of Environmental Engineering
The present work demonstrates the application of various sizes of ordered mesoporous carbon nanospheres (OMCS) with diameters of 46-130 nm as an active anode material for Li-ion batteries (LIB). The physical and chemical properties of OMCS have been evaluated by performing scanning electron microscopy (SEM), transmission electron microscopy (TEM), N-2 adsorption-desorption analysis; small-angle scattering system (SAXS) and X-ray diffraction (XRD). The electrochemical analysis of using various sizes of OMCS as anode materials showed high capacity and rate capability with the specific capacity up to 560 mA.h.g(-1) at 0.1 C after 85 cycles. In terms of performance at high current rate compared to other amorphous carbonaceous materials; a stable and extremely high specific capacity of 240 mA.h.g(-1) at 5 C after 15 cycles was achieved. Such excellent performance is mainly attributed to the suitable particle size distribution of OMCS and intimate contact between OMCS and conductive additives; which can be supported from the TEM images. Results obtained from this study clearly indicate the excellence of size distribution of highly integrated mesoporous structure of carbon nanospheres for LIB application.
Sulfur-doped graphene quantum dot-based paper sensor for highly sensitive and selective detection of 4-nitrophenol in contaminated water and wastewater
(2019-08-27)
Nguyen Thi Ngoc Anh
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Chang, Pei-Yi
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Doong, Ruey-An
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環境工程研究所
;
Institute of Environmental Engineering
4-Nitrophenol (4-NP) is a promulgated priority pollutant, which can cause a negative impact on human health. The development of a direct and effective technique for the rapid detection and screening of 4-NP is, therefore, of urgent need. In this study, the blue luminescent sulfur-doped graphene quantum dots (S-GQDs) with a size of 1-5 nm are fabricated using a one-step pyrolysis procedure in the presence of citric acid and 3-mercaptosuccinic acid. The S-GQDs exhibit a strong emission band at 450 nm under the excitation of 330 nm UV light. 4-NP can serve as the fluorescence quencher by the pi-pi interaction with S-GQD, resulting in the linear decrease in fluorescence intensity after the addition of various 4-NP concentrations ranging from 10 nM to 200 mu M. The S-GQDs serve as the sensing probe to enhance the analytical performance on 4-NP detection with the limit of detection values of 0.7 and 3.5 nM in deionized water and wastewater, respectively. The S-GQD based sensing platform can be used to detect 4-NP in different matrices of water and wastewater. In addition, the detected percentages of spiked 4-NP concentrations in the presence of different matrices and interferences are in the range of (98 +/- 5)-(108 +/- 2)%. Moreover, the S-GQD based paper sensor can rapidly screen 4-NP in wastewater within 1 min. Results obtained in this study clearly demonstrate the superiority of S-GQDs as a promising fluorescence probe for highly sensitive and selective detection of a wide concentration range of 4-NP in deionized water and wastewater.
Ultra-small CoO nanocrystals anchored on reduced graphene oxide for enhanced lithium storage in lithium ion batteries
(2017-06-01)
Bindumadhavan, Kartick
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Chang, Pei-Yi
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Yeh, Ming-Hsiu
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Doong, Ruey-an
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環境工程研究所
In this study, we have developed a facile and simple route for preparation of ultrafine CoO/reduced graphene oxide (rGO) nanohybrids with tunable particle size and crystallinity for lithium-ion battery ( LIB) application. At the optimized calcination time of 60 min, the homogeneous and ultrafine CoO nanoparticles with mean size of 4.5 nm can be intimately attached onto rGO surface to rapidly transport Li ions and electrons. The CoO/rGO exhibits excellent rate capability and high specific capacity of 520 mAh/g at 2400 mA/g. In addition, the capacity can be recovered to 900 mAh/g at 150 mA/g after 60 cycles, indicating the superior electrochemical performance of CoO/rGO for LIB applications.
Ultrafine CoO Embedded Reduced Graphene Oxide Nanocomposites: A High Rate Anode for Li-Ion Battery
(2016-11-01)
Bindumadhavan, Kartick
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Yeh, Ming-Hsiu
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Chou, Tsu-Chin
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Chang, Pei-Yi
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Doong, Rueyan
A novel and simple strategy for the synthesis of cobalt oxide decorated reduced graphene oxide (CoO-rGO) nanocomposites was developed as a high performance anode for lithium ion battery (LIB). The CoO-rGO nanocomposites were prepared by simultaneous reduction of GO and Co2+ in the presence of NaBH4. Addition of 15 wt% rGO produced a narrow size distribution of ultra-fine CoO nanoparticles with nano-dimensional contact between CoO and rGO leading to an excellent electrochemical performance. The reversible capacity of CoO-rGO nanocomposites is between 1140 and 1260 mAh/g at the current density of 150 mA/g and sustained at 473 mAh/g at high current density of 2400 mA/g. In addition to the excellent rate capability of 15 wt% CoO-rGO, a reversible capacity of 690 mAh/g is achieved at 600 mA/g after 60 cycles. In addition, XPS spectra and XRD patterns of CoO-rGO after cycling clearly indicate the involvement of electrolyte into CoO nanoparticles during intercalation-deintercalation cycling, and lead to the transformation of Co species from Co2+ to Co3+ for the enhanced electrochemical performance at high current density.