Browsing by Issue Date, starting with "2016-08-17"

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Scalable Patterning of MoS2 Nanoribbons by Micromolding in Capillaries
(2016-08-17)
Hung, Yu-Han
;
Lu, Ang-Yu
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Chang, Yung-Huang
;
Huang, Jing-Kai
;
Chang, Jeng-Kuei
In this study, we report a facile approach to prepare dense arrays of MoS2 nanoribbons by combining procedures. of micromolding in capillaries (MIMIC) and thermolysis of thiosalts ((NH4)(2)MoS4) as the printing ink. The obtained MoS2 nanoribbons had a "thickness reaching as. low as 3.9 nm, a width ranging from 157 to 465 nm, and a length up to 2 cm. MoS2 nanoribbons with an extremely high aspect ratio (lengthiwidtfi) of similar to 7.4 X 10(8) were achieved. The MoS2 pattern can be printed on versatile substrates, such as SiO2/Si, sapphire, Au film, FTO/glass, and graphene-coated glass. The degree of crystallinity of the as-prepared MoS2 was discovered to be adjustable by varying the temperature through postannealing. The high-temperature thermolysis (1000 degrees C) results in high-quality conductive samples, and field-effect transistors, based on the patterned MoS2 nanoribbons were demonstrated and characterized, where the carrier mobility was comparable to that of thin-film MoS2. In contrast, the low-temperature-treated samples (170 degrees C) result in a unique nanocrystalline MOSx structure (x approximate to 2.5), where the abundant and exposed edge sites were obtained from highly dense arrays of nanoribbon structures by this MIMIC patterning method,: The patterned MoSx was revealed to have superior electrocatalytic efficiency (an overpotential of similar to 211 mV at 10 mA/cm(2) and a Tafel slope of 43 mV/dec) in the hydrogen evolution reaction (HER) when compared to the thin-film MoS2. The report introduces a new concept for rapidly fabricating cost-effective and high-density MoS2/MoSx natiostructures on versatile substrates, which may pave the way for potential applications in nanoelectronics/optoelectronics and frontier energy materials.
Coherent acoustic phonon oscillation accompanied with backward acoustic pulse below exciton resonance in a ZnO epifilm on oxide-buffered Si(111)
(2016-08-17)
Lin, Ja-Hon
;
Shen, Yu-Kai
;
Liu, Wei-Rein
;
Lu, Chia-Hui
;
Chen, Yao-Hui
Unlike coherent acoustic phonons (CAPs) generated from heat induced thermal stress by the coated Au film, we demonstrated the oscillation from c-ZnO epitaxial film on oxide buffered Si through a degenerate pump-probe technique. As the excited photon energy was set below the exciton resonance, the electronic stress that resulted from defect resonance was used to induce acoustic wave. The damped oscillation revealed a superposition of a high frequency and long decay CAP signal with a backward propagating acoustic pulse which was generated by the absorption of the penetrated pump beam at the Si surface and selected by the ZnO layer as the acoustic resonator.
Highly Sensitive and Selective Detection of Nanomolar Ferric Ions Using Dopamine Functionalized Graphene Quantum Dots
(2016-08-17)
Chowdhury, Ankan Dutta
;
Doong, Ruey-an
;
環境工程研究所
;
Institute of Environmental Engineering
The good stability, low cytotoxicity, and excellent photoluminescence property of graphene quantum dots (GQDs) make them an emerging class of promising materials in various application fields ranging from sensor to drug delivery. In the present work, the dopamine-functionalized GQDs (DA-GQDs) with stably bright blue fluorescence were successfully synthesized for low level Fe3+-ions detection. The as-synthesized GQDs are uniform in size with narrow-distributed particle size of 4.5 +/- 0.6 nm and high quantum yield of 10.2%. The amide linkage of GQDs with dopamine, confirmed by using XPS and FTIR spectra, results in the specific interaction between Fe3+ and catechol moiety of dopamine at the interfaces for highly sensitive and selective detection of Fe3+. A linear range of 20 nM to 2 mu M with a detection limit of 7.6 nM is obtained for Fe3+ detection by DA-GQDs. The selectivity of DA-GQDs sensing probe is significantly excellent in the presence of other interfering metal ions. In addition, the reaction mechanism for Fe3+ detection based on the complexation and oxidation of dopamine has been proposed and validated. Results obtained in this study clearly demonstrate the superiority of surface functionalized GQDs to Fe3+ detection, which can pave an avenue for the development of high performance and robust sensing probes for detection of metal ions and other organic metabolites in environmental and biomedical applications.
Photocreating supercooled spiral-spin states in a multiferroic manganite
(2016-08-18)
Sheu, Y. M.
;
Ogawa, N.
;
Kaneko, Y.
;
Tokura, Y.
;
電子物理學系
We demonstrate that the dynamics of the ab-spiral-spin order in a magnetoelectric multiferroic Eu0.55Y0.45MnO3 can be unambiguously probed through optical second harmonic signals, generated via spin-induced ferroelectric polarization. In the case of weak excitation, the ferroelectric and the spiral-spin order remains interlocked, both relaxing through spin-lattice relaxation in the nonequilibrium state. When the additional optical pulse illuminating the sample is intense enough to induce a local phase transition thermally, the system creates ametastable state of the bc-spiral-spin order (with the electric polarization P parallel to c) via supercooling across the first-order phase transition between the ab and bc spiral. The supercooled state of the bc-spiral spin is formed in the thermodynamical ground state of the ab spiral (P parallel to a), displaying a prolonged lifetime with strong dependence on the magnetic field along the a axis. The observed phenomena provide a different paradigm for photoswitching between the two distinct multiferroic states, motivating further research into a direct observation of the photocreated supercooled bc-spiral spin in multiferroic manganites.
Nanochips of Tantalum Oxide Nanodots as artificial-microenvironments for monitoring Ovarian cancer progressiveness
(2016-08-18)
Dhawan, Udesh
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Wang, Ssu-Meng
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Chu, Ying Hao
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Huang, Guewha S.
;
Lin, Yan Ren
Nanotopography modulates cell characteristics and cell behavior. Nanotopological cues can be exploited to investigate the in-vivo modulation of cell characteristics by the cellular microenvironment. However, the studies explaining the modulation of tumor cell characteristics and identifying the transition step in cancer progressiveness are scarce. Here, we engineered nanochips comprising of Tantalum oxide nanodot arrays of 10, 50, 100 and 200 nm as artificial microenvironments to study the modulation of cancer cell behavior. Clinical samples of different types of Ovarian cancer at different stages were obtained, primary cultures were established and then seeded on different nanochips. Immunofluorescence (IF) was performed to compare the morphologies and cell characteristics. Indices corresponding to cell characteristics were defined. A statistical comparison of the cell characteristics in response to the nanochips was performed. The cells displayed differential growth parameters. Morphology, Viability, focal adhesions, microfilament bundles and cell area were modulated by the nanochips which can be used as a measure to study the cancer progressiveness. The ease of fabrication of nanochips ensures mass-production. The ability of the nanochips to act as artificial microenvironments and modulate cell behavior may lead to further prospects in the markerless monitoring of the progressiveness and ultimately, improving the prognosis of Ovarian cancer.
Infrared Spectroscopic Investigation of the Acidic CH Bonds in Cationic n-Alkanes: Pentane, Hexane, and Heptane
(2016-08-18)
Xie, Min
;
Matsuda, Yoshiyuki
;
Fujii, Asuka
;
應用化學系
;
應用化學系分子科學碩博班
Radical cations of n-alkanes (pentane, hexane, and heptane) in the gas phase are investigated by infrared predissociation spectroscopy with the argon Or nitrogen tagging. All-trans and gauche-involving conformers are identified for these cations by comparisons of observed infrared spectra and vibrational simulations. Intense CH stretch bands are observed in the frequency region lower than the normal alkyl CH stretch frequency. These low frequencies and high intensities of the CH stretch bands are caused by the CH bond weakening and the enhanced positive charge of the hydrogen atoms through the delocalization of the sigma electron in the CH bonds. These effects of the delocalization of the a electron result in the enhanced acidity of the CH bonds. The conformation as well as alkyl chain length dependence of the acidity of the CH bonds is demonstrated by the CH stretch frequency shift trend.
Humidity-switch chromism of aniline-pentamer in Nafion
(2016-08-19)
Lin, Yen-Hao
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Hsiao, Yu-Sheng
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Lu, Hsiao-Chi
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Chen, Peilin
;
Whang, Wha-Tzong
Aniline-pentamer (AP) in Nafion triggered with humidity content displays an interesting chromism from blue to pink, which is much wider of color shift than general polyaniline. Thermogravimetric analysis confirms the reversal color change related to the moisture content in the sample. IR absorption spectra make known AP having high degree of protonation at lower water content. UV-Vis absorption expose the chromism process having something more than just protonation. The change of electronic energy levels and PL spectra reveal that there must be a complex interaction in NaAP. Raman scattering mapping confirms that drying causes the - SO3- hydrophilic channels transforming to isolated domains dispersed in matrix, which induces heavy protonation and complexation of AP with - SO3- groups. We can infer that the interesting humidity-switch chromism is due to the reversible protonation/deprotonation as well as complexation of AP with - SO3- groups through the reversible change of Nafion\'s morphology.
Status and Prospects of ZnO-Based Resistive Switching Memory Devices
(2016-08-19)
Simanjuntak, Firman Mangasa
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Panda, Debashis
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Wei, Kung-Hwa
;
Tseng, Tseung-Yuen
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材料科學與工程學系
In the advancement of the semiconductor device technology, ZnO could be a prospective alternative than the other metal oxides for its versatility and huge applications in different aspects. In this review, a thorough overview on ZnO for the application of resistive switching memory (RRAM) devices has been conducted. Various efforts that have been made to investigate and modulate the switching characteristics of ZnO-based switching memory devices are discussed. The use of ZnO layer in different structure, the different types of filament formation, and the different types of switching including complementary switching are reported. By considering the huge interest of transparent devices, this review gives the concrete overview of the present status and prospects of transparent RRAM devices based on ZnO. ZnO-based RRAM can be used for flexible memory devices, which is also covered here. Another challenge in ZnO-based RRAM is that the realization of ultra-thin and low power devices. Nevertheless, ZnO not only offers decent memory properties but also has a unique potential to be used as multifunctional nonvolatile memory devices. The impact of electrode materials, metal doping, stack structures, transparency, and flexibility on resistive switching properties and switching parameters of ZnO-based resistive switching memory devices are briefly compared. This review also covers the different nanostructured-based emerging resistive switching memory devices for low power scalable devices. It may give a valuable insight on developing ZnO-based RRAM and also should encourage researchers to overcome the challenges.
Green synthesis of multifunctional mesoporous composites from display panel glasses for selective adsorption of metal ions
(2016-08-20)
Tsai, Cheng Kuo
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Doong, Ruey-an
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Hung, Huan-Yi
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環境工程研究所
;
Institute of Environmental Engineering
Ultrathin flexible silicon photodetector with silver nanowires plasmonic structure for chemiluminescence sensing
(2016-08-20)
Liu, Lai-Yi
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Lin, Ching-Chnag
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Liu, Shuenyu
;
Sun, Wen-Hsien
;
Cheng, Chieh
Fabrication of alpha-MnO2 nano-particle and nano-rod composite electrodes for capacitive deionization
(2016-08-20)
Chen, Yi-Han
;
Juang, Yaju
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Huang, Chihpin
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環境工程研究所
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Institute of Environmental Engineering
Reduced graphene oxide based bimetallic Ni/Fe nanohybrids for rapid dechlorination of trichloroethylene
(2016-08-20)
Sahu, Rama
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Li, Dong-Lin
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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
Gold nanorods self-assembly by dielectrophoretic and applications in solar cells
(2016-08-20)
Lin, Ching-Chang
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Sun, Wen-Hsien
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Liu, Shuenyu
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Liu, Lai-Yi
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Cheng, Chieh
Acidity of a TiO2-ZrO2 adsorbent modified with phosphate or tungstate species
(2016-08-20)
Chang, Sue-Min
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Shan, Po-Fan
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環境工程研究所
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Institute of Environmental Engineering
Observation of switchable photoresponse of a monolayer WSe2-mos2 lateral heterostructure via photocurrent spectral atomic force microscopic imaging
(2016-08-20)
Son, Youngwoo
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Li, MIng-Yang
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Cheng, Chia-Chin
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Wei, Kung-Hwa
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Liu, Pingwei
Organic bulk heterojunction photovoltaics with cyclopenteno[60]fullerene monoadducts as n-type materials display superior power conversion efficiency than with PC61BM
(2016-08-20)
Chuang, Shih-Ching
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Tseng, Po-Yen
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應用化學系
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Department of Applied Chemistry
Dispersible nanocomposites of functionalized graphene oxide reinforced polyethylene for packaging application
(2016-08-20)
Toh, Guat Yee
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Ong, Hui
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Bindumadhavan, Kartick
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Doong, Ruey-An
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環境工程研究所
Flexible and miniaturized msm biomolecular photodetector for hydrogen peroxide sensing via chemiluminescence
(2016-08-20)
Lin, Ching-Chang
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Liu, Lai-Yi
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Sun, Wen-Hsien
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Liu, Shuenyu
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Cheng, Chieh
Development of molybdenum disulphide-graphene quantum dots nanostructure for electrochemical applications
(2016-08-20)
Bindumadhavan, Kartick
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Sahu, Rama
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Doong, Ruey-An
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環境工程研究所
;
Institute of Environmental Engineering
Enhanced reactivity of metal/metal oxide-porous carbon nanocomposites for electrochemical and photocatalytic applications
(2016-08-20)
Doong, Ruey-An
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Lin, Chia-Sheng
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Bindumadhavan, Kartick
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環境工程研究所
;
Institute of Environmental Engineering