Browsing by Author "Chen, Jing-Yu"

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A facile route to prepare PdPt alloys for ethanol electro-oxidation in alkaline electrolyte
(2011-01-31)
Lin, Sheng-Chieh
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Chen, Jing-Yu
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Hsieh, Yi-Fan
;
Wu, Pu-Wei
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材料科學與工程學系
We adopted a displacement reaction in acidic solution that enabled the spontaneous reduction of Pd and Pt cations in conjunction with corrosive dissolution of Ni. The composition for the PdPt was adjusted by varying the concentration of Pd and Pt cations. From SEM images and XRD patterns, the PdPt formed an fcc alloy uniformly deposited on the Ni substrate. Electro-oxidation of ethanol was conducted in alkaline electrolyte for samples of Pd, Pt, and PdPt alloys. In cyclic voltammetric profiles, the Pd(77)Pt(23) revealed the highest electrocatalytic ability in both apparent current and mass activity, followed by Pd(87)Pt(13), Pd, and Pt. Similar behaviors were observed in life time measurements in which stable performances for ethanol electro-oxidation were obtained. (C) 2010 Elsevier B.V. All rights reserved.
Chemical bath deposition of IrO2 films on ITO substrate
(2014-11-01)
Chen, Jing-Yu
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Chen, Yong-Min
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Sun, Yu
;
Lee, Jyh-Fu
;
Chen, San-Yuan
A chemical bath is shown to deposit an IrO2 film on an ITO substrate. The chemical bath is prepared by mixing an Ir precursor (Na3IrCl6 center dot xH(2)O), an oxidizer (NaClO), a complexing agent (NaNO2), and a complex agent/stabilizer (NaOH) in an aqueous solution at a molar ratio of 1:1.5:10:30. From the UV-vis absorption spectra, complexes such as [Ir(OH)(6)]m(3-), [Ir(NO2)(4)Cl-2](3-), and [Ir(NO2)(3)Cl-3](3-) are identified. These complexes are relatively stable, minimizing the undesirable homogeneous precipitation of IrO2 nanoparticles in favor of the heterogeneous growth of the IrO2 film on the ITO substrate. Diffraction patterns from the as-deposited IrO2 film reveal an amorphous structure. In addition, profiles from X-ray absorption spectroscopy and X-ray photoelectron spectroscopy indicate that the oxidation state of the Ir in the as-deposited IrO2 film is +4. Thermogravimetric analysis confirms the inclusion of 10 wt% hydrated water in the as-deposited IrO2 film. Scanning electron microscope images reveal a continuous solid film with a smooth surface. The amorphous IrO2 film becomes rutile IrO2 phase after a mild heat treatment in air. (c) 2014 Elsevier Ltd and Techna Group S.r.l. All rights reserved.
Effect of Crystallinity on the Optical Reflectance of Cylindrical Colloidal Crystals
(2011)
Lai, Chun-Han
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Yang, Yu-Lin
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Chen, Li-Yin
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Huang, Yi-Jui
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Chen, Jing-Yu
We fabricate cylindrical colloidal crystals (CCCs) via electrophoretic depositions of polystyrene microspheres on a carbon fiber in a concentric arrangement. Images from optical and scanning electron microscope indicate that the CCCs of 460 nm microspheres reveal a semicrystalline structure in close-packed lattice, while the CCCs of 660 exhibit an amorphous arrangement. In optical reflectance spectra, both CCCs demonstrate a dispersive photonic bandgap as compared to that from planar counterparts. The curved contour for the CCCs renders incident light interacting with reflecting planes at slightly different angles, leading to a notable reduction in the reflectance intensity and minor relocation of photonic bandgap contingent on their crystallinity. (C) 2011 The Electrochemical Society. [DOI: 10.1149/1.3536511] All rights reserved.
Electrochemical degradation of Nafion ionomer to functionalize carbon support for methanol electro-oxidation
(2011-10-15)
Hsieh, Yu-Chi
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Chen, Jing-Yu
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Wu, Pu-Wei
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材料科學與工程學系
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Department of Materials Science and Engineering
An effective electrochemical route to produce functional groups on carbon surface is demonstrated. Cyclic voltammetric (CV) sweeps are performed in 0.5 M H(2)SO(4) electrolyte on electrodes containing carbon cloth, Vulcan XC72R, and Nation ionomer. With supply of ambient oxygen, the generation of hydroxyl radicals from the oxygen reduction reaction during CV cycles initiates the decomposition of Nation ionomer that leads to formation of oxygenated functional groups on the carbon surface. Ion chromatography confirms the dissolution of sulfate anions upon CV scans. Raman analysis suggests a minor alteration for the carbon structure. However, X-ray photoelectron spectroscopy indicates a significant increase of oxygenated functional groups in conjunction with notable reduction in the fluorine content. The amount of the oxygenated functional groups is determined by curve fitting of C is spectra with known constituents. These functional groups can also be found by immersing the as-prepared electrode in a solution containing concentrated residues from Nation ionomer decomposition. The functionalized electrode allows a 170% increment of Pt ion adsorption as compared to the reference sample. After electrochemical reductions, the functionalized electrode reveals significant improvements in electrocatalytic abilities for methanol oxidation, which is attributed to the oxygenated functional groups that facilitates the oxidation of CO on Pt. (C) 2011 Elsevier B.V. All rights reserved.
Electrochemical reduction of CO(2) by Cu(2)O-catalyzed carbon clothes
(2009-05-15)
Chang, Tin-Yu
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Liang, Ru-Meng
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Wu, Pu-Wei
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Chen, Jing-Yu
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Hsieh, Yu-Chi
Cu(2)O cubes with average edge lengths of 640 nm were prepared by a chemical reduction approach. The as-synthesized Cu(2)O particles were deposited on carbon clothes for electrochemical characterizations in cyclic voltammetry (CV) and potentiostatic measurements. In 0.5 M NaOH electrolytes saturated with N(2) or CO(2), both the Cu(2)O and carbon clothes were stable at the potential range of 0 to -1.7 V. Comparisons in the Current responses from the CV and potentiostatic measurements suggested the Cu(2)O with notable catalytic abilities for the CO(2) reduction. The mass activity was estimated at 0.94 mA/mg. Chemical analysis from gas chromatography confirmed the methanol to be the predominant product. (C) 2009 Elsevier B.V. All rights reserved.
Electrochemical reduction of CO2 by Cu2O-catalyzed carbon clothes
(2009-05-15)
Chang, Tin-Yu
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Liang, Ru-Meng
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Wu, Pu-Wei
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Chen, Jing-Yu
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Hsieh, Yu-Chi
Cu2O cubes with average edge lengths of 640 nm were prepared by a chemical reduction approach. The as-synthesized Cu2O particles were deposited on carbon clothes for electrochemical characterizations in cyclic voltammetry (CV) and potentiostatic measurements. In 0.5 M NaOH electrolytes saturated with N-2 or CO2, both the Cu2O and carbon clothes were stable at the potential range of 0 to -1.7 V. Comparisons in the Current responses from the CV and potentiostatic measurements suggested the Cu2O with notable catalytic abilities for the CO2 reduction. The mass activity was estimated at 0.94 mA/mg. Chemical analysis from gas chromatography confirmed the methanol to be the predominant product. (C) 2009 Elsevier B.V. All rights reserved.
Electroless deposition of Ru films on Si substrates with surface pretreatments
(2013-02-01)
Chen, Jing-Yu
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Huang, Shiau-Lin
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Wu, Pu-Wei
;
Lin, Pang
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材料科學與工程學系
Electroless Ru depositions on Si substrates undergoing surface pretreatments such as hydrogen fluoride (HF) etching, HF etching and activation, as well as HF etching, sensitization, and activation are explored. The plating bath contains K2RuCl5 center dot xH(2)O, NaClO, NaOH, and NaNO2 at appropriate ratios. Continuous electroless Ru film is unable to obtain on the as-received Si wafer because the native oxide inhibits the process of nucleation and growth. In contrast, after surface pretreatments, dense and continuous Ru films are observed at reasonable growth rates. Contact angle measurements indicate a relatively hydrophilic surface after sensitization and activation, which leads to faster Ru film growths and larger surface roughness as compared to the HF-etched sample. X-ray photoelectron spectra confirm the formation of Sn and Pd nuclei and their presence promotes the heterogeneous growth of Ru films as evidenced by images from scanning electron microscope. In addition, depth profiling from Auger electron spectrometer suggests a uniform composition across the film thickness despite part of the Ru exists in an oxidized form. (C) 2012 Elsevier B.V. All rights reserved.
Electroless Deposition of Ru Films Via an Oxidative-Reductive Mechanism
(2011)
Chen, Jing-Yu
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Hsieh, Yu-Chi
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Wang, Li-Yeh
;
Wu, Pu-Wei
;
材料科學與工程學系
An electroless Ru plating bath is prepared by mixing Ru precursor (K(2)RuCl(5).xH(2)O), oxidizer (NaClO), stabilizer (NaOH), and reducing agent (NaNO(2)) simultaneously in deionized water at a molar ratio of 1:1:20:10. Instead of conventional direct reduction route, the RuCl(5)(2-) experiences an oxidative-reductive sequence to form metallic Ru on an activated Si substrate. Spectra from ultraviolet-visible and X-ray absorption spectroscopy indicate that the RuCl(5)(2-) is oxidized to form RuO(4) initially, followed by a slight reduction becoming RuO(4)(2-). The RuO(4)(2-) solution is relatively stable and is able to undergo further reduction to render metallic Ru via heterogeneous nucleation and growth. Images from scanning electron microscope demonstrate a solid film of 100 nm with scattered protrusions and cavities after 120 min plating time. Analysis from atomic force microscope determines its surface roughness of 7.8 nm. From X-ray diffraction patterns, the as-deposited film reveals an amorphous structure but turns crystalline after Ar annealing at 400 degrees C for 2 h. Curve-fitting of Ru 3p(3/2) signal from X-ray photoelectron spectroscopy suggests a film composition of 92.49 atom % Ru and 7.51 atom % RuO(2). The electroless Ru plating bath exhibits impressive life time (137 h) and negligible homogeneous precipitation without involving surfactants and unnecessary chemical additives. (C) 2011 The Electrochemical Society. [DOI: 10.1149/1.3592996] All rights reserved.
Mechanical alloying preparation of La0.6Ca0.4CoIr0.25O3.5-delta as a bifunctional electrocatalyst in alkaline electrolyte
(2008)
Chang, Yun-Min
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Wu, Pu-Wei
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Wu, Cheng-Yeou
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Hsieh, Yi-Fan
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Chen, Jing-Yu
La0.6Ca0.4CoIr0.25O3.5-delta was prepared by a mechanical alloying process from mixtures of La0.6Ca0.4CoO3 and IrO2. Scanning electron microscopy images on the resulting powders exhibited particles with irregular shape at 300-500 nm in size. X-ray diffraction analysis confirmed formation of a perovskite with complete disappearance of rutile signals from IrO2, indicating successful incorporation of Ir4+ at the Co3+ sites. Supported on carbon nanocapsules, the La0.6Ca0.4CoIr0.25O3.5-delta demonstrated superior performance over those of La0.6Ca0.4CoO3 in both charging and discharging current density-voltage polarizations. In addition, galvanostatic charging and discharging measurements at 25 and 100 mA/cm(2) indicated that the electrocatalytic abilities of La0.6Ca0.4CoIr0.25O3.5-delta are stable and sustainable.
Preparation and characterization of ruthenium films via an electroless deposition route
(2010-10-01)
Chen, Jing-Yu
;
Wang, Li-Yeh
;
Wu, Pu-Wei
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材料科學與工程學系
;
Department of Materials Science and Engineering
A metallic Ru film was prepared by an electroless deposition method, followed by hydrogen reduction treatment. The electroless deposition formulation produced a solid film on a Cu-coated Si substrate at 40 degrees C preactivated by PdCl(2) solution. Chemicals including K(2)RuCl(5)center dot xH(2)O, NaNO(2), NaOH, and NaClO were mixed in a proper ratio that enabled heterogeneous nucleation and film growth. Results from X-ray photoelectron spectroscopy (XPS) on the as-deposited films confirmed the presence of RuO(x) and Ru, while X-ray diffraction (XRD) pattern suggested an amorphous nature. Planar images from a scanning electron microscope revealed a rather smooth surface at thickness less than 250 nm. Above that formation of surface crack and partial detachment from the substrate were observed. After hydrogen reduction at 200 degrees C for 2 h, we obtained a metallic Ru film, as confirmed by XPS and XRD. In addition, the surface roughness was increased due to the formation of pinholes that was caused by the volume contraction associated with RuO(x) reduction to Ru. (C) 2010 Elsevier B.V. All rights reserved.