E E E EE E E
E--------mail: mail: mail: mail: mail: mail: mail: mail: [email protected]@[email protected]@[email protected]@[email protected]@nck.edu.tw
Acknowledgements
The work was supported by Research Grant o. SC 98-2221 -E- 390-013-MY2 and SC 98-2221-E-006-082-MY3, ational Science Council of Taiwan.
• SEM Morphology –as-synthesizedCuO nanowire arrays
• FE-TEM & Phase Resolution
-Morphology, Crystallography, and Composition characterization
Hsin Hsin Hsin
Hsin----Ying Lin Ying Lin Ying Lin Ying Lin (林欣穎林欣穎林欣穎林欣穎)1 Michael Michael RongMichael Michael RongRong----ShieRongShieShie HuangShieHuangHuangHuang (黃榮喜黃榮喜黃榮喜黃榮喜)2 RueyRueyRueyRuey----Chi WangChi WangChi Wang (王瑞琪Chi Wang 王瑞琪王瑞琪王瑞琪)3 ****ChuanChuanChuanChuan----PuPuPu LiuPuLiuLiu (劉全璞Liu 劉全璞劉全璞劉全璞)1,2
Abstract Abstract
Aligned Cu2O porous nanowires were prepared for the first time by the reduction of aligned single-crystalline CuO nanowires by treatments of hydrogen/nitrogen plasma in an inductive coupled plasma (ICP) etching system at room temperature. Scanning electron microscopy (SEM), high- resolution transmission electron microscopy (HRTEM), and energy dispersive spectroscopy (EDS) show that the morphology, microstructures and compositions of CuO nanowires can be varied significantly by varying the power, time, and mixture gases of plasma treatment. The reduction of CuO to Cu2O increases with the ratio of H2 to N2 gas and time of plasma treatment. The morphology and microstructures of nanowires transformed form single-crystalline solid nanowires to poly- crystalline porous nanowires constructed of single-crystalline nanoparticles. The sizes of the nanoparticles are in the range of 5~10 nm. Raman spectra of the nanowires show excellent surface enhanced Raman scattering (SERS) effects in detecting absorbed 4-ABT molecules under 633 nm excitations after the treatment of H2plasma. The enhanced SERS of nanowires after plasma treatment is attributed to improved electrical conductivity and shape effects. The work provides a plasma-assisted method to vary the composition and morphology of 1D nanomaterials at low temperature, which are promising for sensing, self-cleaning, electronic devices, and drug delivery applications.
Improved
Improved surface enhanced Raman scattering surface enhanced Raman scattering of Cu of Cu
22O p O porous orous nanowires nanowire s transformed from
transformed from CuO CuO nanowires nanowires by plasma treatments by plasma treatment s
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1Institute of Nanotechnology and Microsystems Engineering, NationInstitute of Nanotechnology and Microsystems Engineering, NationInstitute of Nanotechnology and Microsystems Engineering, NationInstitute of Nanotechnology and Microsystems Engineering, National Cheng Kung University, Tainan 70101, Taiwanal Cheng Kung University, Tainan 70101, Taiwanal Cheng Kung University, Tainan 70101, Taiwanal Cheng Kung University, Tainan 70101, Taiwan
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2Department of Materials Science and Engineering, National Cheng Department of Materials Science and Engineering, National Cheng Department of Materials Science and Engineering, National Cheng Department of Materials Science and Engineering, National Cheng Kung University, Tainan 70101, TaiwanKung University, Tainan 70101, TaiwanKung University, Tainan 70101, TaiwanKung University, Tainan 70101, Taiwan
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3Department of Chemical and Materials Engineering, National UniveDepartment of Chemical and Materials Engineering, National UniveDepartment of Chemical and Materials Engineering, National UniveDepartment of Chemical and Materials Engineering, National University of Kaohsiung, Kaohsiung 81148, Taiwanrsity of Kaohsiung, Kaohsiung 81148, Taiwanrsity of Kaohsiung, Kaohsiung 81148, Taiwanrsity of Kaohsiung, Kaohsiung 81148, Taiwan
Fig. 1 SEM images of CuO nanoneedles synthesized by heating copper substrates. (a) top-view images of CuO nanoneedles formed by directly heating a Cu foil; (b) is an enlarged SEM image of CuO nanowires.
Fig. 2 TEM characterizations of an as-synthesized CuO nanowire (a) bright-field image, (b) electron diffraction pattern and (c) high-resolution image.
• Plasma treatment–reduction ofCuO nanowire arrays
Fig. 3 (a) SEM image of Cu2O nanowires prepared by the reduction of CuO nanowires in pure hydrogen plasma with the power of 300 W at room temperature for 1 min. (b) SEM image of porous Cu2O nanowires prepared by the reduction of CuO nanowires with the 300W plasma treatment of H2/.2(1:1) mixture gases at room temperature for 1 min. (c) SEM image of porous Cu2O nanowires prepared by the reduction of CuO nanowires with the 300W plasma treatment of H2/.2(1:4) mixture gases at room temperature for 1 min.
H
H2250sccm50sccm HH22/./.2225/25 25/25 sccmsccm HH22/./.2210/40 10/40 sccmsccm
2011 3rd International Symposium on Advanced Plasma 2011 3rd International Symposium on Advanced Plasma 2011 3rd International Symposium on Advanced Plasma 2011 3rd International Symposium on Advanced Plasma Science and its Applications for Nitrides and
Science and its Applications for Nitrides and Science and its Applications for Nitrides and
Science and its Applications for Nitrides and NanomaterialsNanomaterialsNanomaterialsNanomaterials
• HR-TEM Resolution
-CuO/Cu2O core-shell nanowire & Cu2O porous nanowires
Fig. 4(a)~(b) are the TEM bright-field image and diffraction pattern of Cu2O nanowires prepared by the reduction of CuO nanowires in pure hydrogen plasma.
(c)~(d) are the TEM bright-field image and diffraction pattern of Cu2O nanowires prepared by the reduction of CuO nanowires with the 300W plasma treatment of H2/.2 (1:1) mixture gases. (e)~(f) are the TEM bright-field image and diffraction pattern of Cu2O nanowires prepared by the reduction of CuO nanowires with the 300W plasma treatment of H2/.2(1:4) mixture gases.
• SERS effects- varied with the composition and morphology
Fig. 6 Raman spectra of 4-ABT loaded on various substrates under 633 nm excitation.
The molecular species receive a strong localized field when the supported metal nanostructures are excited by a laser at the resonance wavelength, thereby producing a stronger Raman signal.
T h e R a m a n i n t e n s i t y i s further increased when they are completely oxidized to form porous Cu2O nanowires.
