Browsing by Author "Kao, Hsien-Ming"

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A Water-Soluble NaCMC/NaPAA Binder for Exceptional Improvement of Sodium-Ion Batteries with an SnO2-Ordered Mesoporous Carbon Anode
(2018-11-23)
Patra, Jagabandhu
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Rath, Purna Chandra
;
Li, Chi
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Kao, Hsien-Ming
;
Wang, Fu-Ming
SnO2@CMK-8 composite, a highly promising anode for Na-ion batteries (NIBs), was incorporated with polyvinylidene difluoride (PVDF), sodium carboxymethylcellulose (NaCMC), sodium polyacrylate (NaPAA), and NaCMC/NaPAA mixed binders to optimize the electrode sodiation/desodiation properties. Synergistic effects between NaCMC and NaPAA led to the formation of an effective protective film on the electrode. This coating layer not only increased the charge-discharge Coulombic efficiency, suppressing the accumulation of solid-electrolyte interphases, but also kept the SnO2 nanoparticles in the CMK-8 matrix, preventing the agglomeration and removal of oxide upon cycling. The adhesion strength and stability towards the electrolyte of the binders were evaluated. In addition, the charge-transfer resistance and apparent Na+ diffusion of the SnO2@CMK-8 electrodes with various binders were examined and post-mortem analyses were conducted. With NaCMC/NaPAA binder, exceptional electrode capacities of 850 and 425 mAh g(-1) were obtained at charge-discharge rates of 20 and 2000 mA g(-1), respectively. After 300 cycles, 90 % capacity retention was achieved. The thermal reactivity of the sodiated electrodes was studied by using differential scanning calorimetry. The binder effects on NIB safety, in terms of thermal runaway, are discussed.
Facile fabrication of titania-ordered cubic mesoporous carbon composite: Effect of Ni doping on photocatalytic hydrogen generation
(2019-07-19)
Rath, Purna Chandra
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Mishra, Mrinalini
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Saikia, Diganta
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Chang, Jeng Kuei
;
Perng, Tsong-Pyng
Hitherto TiO2 is the most popular catalyst for photocatalytic H-2 generation and reduction of organic pollutants due to its chemical inertness, high activity, and abundance. In this work, ordered mesoporous carbon CMK-8 supported TiO2 nanoparticles loaded with non-noble metal Ni, denoted as Ni-TiO2@CMK-8 are fabricated for application in photocatalytic H-2 generation. Our results demonstrate that the developed composite exhibit exceptional photocatalytic activity for H-2 generation (3556 mu mol g(-1)) under 300 W Xe lamp irradiation (with an external quantum efficiency of 37.9%), which is around 10 times higher than pure TiO2 and 4 times that of TiO2@CMK-8. The enhanced photocatalytic performance is attributed to the well-dispersed TiO2 in the ordered mesoporous carbon structure of CMK-8. The performance is boosted by the black body-like light absorbance of CMK-8 and plasmonic effect of Ni. Enhanced UV-visible light absorbance, large surface area and the loaded Ni metal synergistically improve the charge-carrier kinetics to attain highly efficient photocatalytic H-2 generation. The Ni-TiO2@CMK-8 composite shows enhanced activity for the reduction of 4-nitrophenol as well. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.