Browsing by Author "Chen, Ying-Chu"

Now showing 1 - 9 of 9

Electrodeposited Fe2TiO5 nanostructures for photoelectrochemical oxidation of water
(2016-09-20)
Lin, Yan-Gu
;
Hsu, Yu-Kuei
;
Lin, Yu-Chang
;
Chen, Ying-Chu
;
材料科學與工程學系
Electrodeposition was used to fabricate nanostructured films of Ti-containing hematite for application to the photoelectrochemical (PEC) splitting of water. The morphology and microstructure of Ti-doped hematite were examined with a scanning electron microscope, X-ray diffraction, Raman spectra and X-ray photoelectron spectra. Optical absorption spectra indicated an enhanced light absorbance in Ti-doped hematite. This Ti doping increased the carrier concentration about ten-fold, confirmed with a Mott-Schottky analysis. The prepared Ti-doped hematite showed a photocurrent enhanced four-fold relative to pristine hematite. Synchrotron-based soft X-ray absorption spectra clearly revealed that a local Fe2TiO5 structure in hematite formed a heterojunction, which decreased the accumulation of photogenerated holes and improved the performance. (C) 2016 Elsevier Ltd. All rights reserved.
Electrodeposited Fe2TiO5 nanostructures for photoelectrochemical oxidation of water
(2016-09-20)
Lin, Yan-Gu
;
Hsu, Yu-Kuei
;
Lin, Yu-Chang
;
Chen, Ying-Chu
;
材料科學與工程學系
Electrodeposition was used to fabricate nanostructured films of Ti-containing hematite for application to the photoelectrochemical (PEC) splitting of water. The morphology and microstructure of Ti-doped hematite were examined with a scanning electron microscope, X-ray diffraction, Raman spectra and X-ray photoelectron spectra. Optical absorption spectra indicated an enhanced light absorbance in Ti-doped hematite. This Ti doping increased the carrier concentration about ten-fold, confirmed with a Mott-Schottky analysis. The prepared Ti-doped hematite showed a photocurrent enhanced four-fold relative to pristine hematite. Synchrotron-based soft X-ray absorption spectra clearly revealed that a local Fe2TiO5 structure in hematite formed a heterojunction, which decreased the accumulation of photogenerated holes and improved the performance. (C) 2016 Elsevier Ltd. All rights reserved.
Hierarchical Fe2O3 nanotube/nickel foam electrodes for electrochemical energy storage
(2016-10-20)
Lin, Yan-Gu
;
Hsu, Yu-Kuei
;
Lin, Yu-Chang
;
Chen, Ying-Chu
;
材料科學與工程學系
An iron-oxide (Fe2O3) nanotube (NT) array is grown directly as a hierarchical nanoarchitecture on a nickel-foam (NF) surface via a simple and cost-effective immersive process. The morphology and microstructure of Fe2O3 NT arrays are systematically examined by scanning electron, transmission electron, Raman, and X-ray photoelectron spectroscopies. The results reveal that the walls of Fe2O3 NT are composed mainly of agglomerated small alpha-Fe2O3 (hematite) monocrystalline nanoparticles filled with a few ZnO monocrystalline particles. The microstructural influence on the pseudocapacitive performance of the obtained Fe2O3 NT/NF electrodes is also investigated via in-situ X-ray absorption spectroscopy (XAS) and electrochemical measurement. The in-situ XAS results regarding charge storage mechanisms of the Fe2O3 NT/NF electrodes show that a Li+ can reversibly insert/desert into/from the 3D mesoporous textures between the Fe2O3 subunits depending on the applied potential. The electrochemical results indicate that the Fe2O3 NT/NF electrode shows highly reversible features and satisfactory rate abilities. Most significantly, the excellent specific capacitance achieved in Fe2O3 NT/NF nanoelectrodes is as great as 300.1 Fg(-1); energy density 75 W h kg(-1) and power density 4.5 kW kg(-1) are obtained, and the Fe2O3 NT/NF nanoelectrode has acceptable cycling stability after 3000 cycles. (C) 2016 Elsevier Ltd. All rights reserved.
Hierarchical Fe2O3 nanotube/nickel foam electrodes for electrochemical energy storage
(2016-10-20)
Lin, Yan-Gu
;
Hsu, Yu-Kuei
;
Lin, Yu-Chang
;
Chen, Ying-Chu
;
材料科學與工程學系
An iron-oxide (Fe2O3) nanotube (NT) array is grown directly as a hierarchical nanoarchitecture on a nickel-foam (NF) surface via a simple and cost-effective immersive process. The morphology and microstructure of Fe2O3 NT arrays are systematically examined by scanning electron, transmission electron, Raman, and X-ray photoelectron spectroscopies. The results reveal that the walls of Fe2O3 NT are composed mainly of agglomerated small alpha-Fe2O3 (hematite) monocrystalline nanoparticles filled with a few ZnO monocrystalline particles. The microstructural influence on the pseudocapacitive performance of the obtained Fe2O3 NT/NF electrodes is also investigated via in-situ X-ray absorption spectroscopy (XAS) and electrochemical measurement. The in-situ XAS results regarding charge storage mechanisms of the Fe2O3 NT/NF electrodes show that a Li+ can reversibly insert/desert into/from the 3D mesoporous textures between the Fe2O3 subunits depending on the applied potential. The electrochemical results indicate that the Fe2O3 NT/NF electrode shows highly reversible features and satisfactory rate abilities. Most significantly, the excellent specific capacitance achieved in Fe2O3 NT/NF nanoelectrodes is as great as 300.1 Fg(-1); energy density 75 W h kg(-1) and power density 4.5 kW kg(-1) are obtained, and the Fe2O3 NT/NF nanoelectrode has acceptable cycling stability after 3000 cycles. (C) 2016 Elsevier Ltd. All rights reserved.
Reversible phase transformation of MnO(2) nanosheets in an electrochemical capacitor investigated by in situ Raman spectroscopy
(2011-01-01)
Hsu, Yu-Kuei
;
Chen, Ying-Chu
;
Lin, Yan-Gu
;
Chen, Li-Chyong
;
Chen, Kuei-Hsien
The reversible phase transformation is reported from hexagonal to monoclinic structure responding to the intercalation/deintercalation of Na(+) between MnO(2) nanosheets upon potential cycling in aqueous electrolyte via an in situ Raman technique. This structural evolution will influence the Na(+) diffusion process in MnO(2) nanosheets and cause phase retention during the self-discharge process.
Reversible phase transformation of MnO2 nanosheets in an electrochemical capacitor investigated by in situ Raman spectroscopy
(2011-01-01)
Hsu, Yu-Kuei
;
Chen, Ying-Chu
;
Lin, Yan-Gu
;
Chen, Li-Chyong
;
Chen, Kuei-Hsien
The reversible phase transformation is reported from hexagonal to monoclinic structure responding to the intercalation/deintercalation of Na+ between MnO2 nanosheets upon potential cycling in aqueous electrolyte via an in situ Raman technique. This structural evolution will influence the Na+ diffusion process in MnO2 nanosheets and cause phase retention during the self-discharge process.
Room-temperature fabrication of Cu nanobrushes as an effective surface-enhanced Raman scattering substrate
(2016)
Hsu, Yu-Kuei
;
Chen, Zhong-Bo
;
Lin, Yu-Chang
;
Chen, Ying-Chu
;
Chen, San-Yuan
A facile route to manufacture an active surface-enhanced Raman-scattering (SERS) substrate based on brush-like Cu nanostructures directly grown on a Cu foil at 23 degrees C was systematically investigated. A hierarchical Cu nanobrush substrate was fabricated in two cycles of electro-oxidation and chemical reduction in sequence; Cu(OH)(2) nanowires (NW) were formed on electro-oxidation, and converted on chemical reduction to Cu NW. Two cycles of this process achieved a brush-like Cu nanostructure; its structure, morphology and composition were examined by XRD, SEM, HRTEM and XPS, respectively. With 4-mercaptobenzoic acid (4-MBA) and chlorothalonil as probe molecules, the SERS experiments showed that the brush-like Cu nanostructures exhibit excellent detection performance, which could serve as effective SERS substrates for ultrasensitive detection. This novel hierarchical SERS substrate shows satisfactory reproducibility and a linear dependence between the analyte concentration and intensity, revealing the advantage of this method for easily scaled production.
Synthesis of Cu2O nanoparticle films at room temperature for solar water splitting
(2016-06-01)
Lin, Yan-Gu
;
Hsu, Yu-Kuei
;
Lin, Yu -Chang
;
Chang, Yu-Hsueh
;
Chen, San -Yuan
A Cu2O nanoparticle film using ZnO nanorods as a sacrificial scaffold was fabricated near 23 degrees C, for applications in photoelectrochemical (PEC) water splitting. Three chemical solutions were utilized to convert ZnO nanorods to a Cu2O nanoparticle film - solutions of CuCl2 and NaOH, NaBH4 and NaOH, respectively. The structural evolution from ZnO through Cu(OH)(2) and metallic Cu to Cu2O phase was analyzed at each stage with X-ray diffraction and X-ray absorption spectra. The energy bandgap was deduced from IPCE; the concentration of carriers and flat-band of a Cu2O nanoparticle film were obtained from a Mott-Schottky plot. Significantly, the Cu2O nanoparticle film exhibited a useful PEC response to water oxidation. This nanostructure synthesized with no energy requirement can not only illustrate a great prospect for solar generation of hydrogen but also offer a blueprint for the future design of photocatalysts. (C) 2016 Elsevier Inc. All rights reserved.
Visible-light-driven photocatalytic carbon-doped porous ZnO nanoarchitectures for solar water-splitting
(2012)
Lin, Yan-Gu
;
Hsu, Yu-Kuei
;
Chen, Ying-Chu
;
Chen, Li-Chyong
;
Chen, San-Yuan
C-doped ZnO hierarchically porous nanoarchitectures were synthesized in situ on indium tin oxide (ITO) through a counter strategy. The PEC performance of the C-doped ZnO nanoarchitectures in the splitting of water without sacrificial reagents was systematically evaluated for the first time. In comparison to other ZnO-based photoanodes in the literature, C-doped ZnO nanoarchitectures exhibit a striking photoresponse. Not only do they have a maximum IPCE value of 95%, but they also have an IPCE at the monochromatic wavelength of 400 nm as high as 26.6%, implying that modification by doping with carbon substantially improves the light utilization and conversion efficiency in the visible region of interest over those obtained using a conventional ZnO structure. This model hybrid photoanode will enable us to design high-activity, high-stability visible-light-driven photoelectrodes in the future.