Improved surface enhanced Raman scattering of Cu2O porous nanowires transformed from CuO nanowires by plasma treatments

Improved surface enhanced Raman scattering of Cu

O porous nanowires transformed from CuO nanowires by plasma treatments

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o.1, University Road, East District, Tainan City 70101 ， Taiwan (R.O.C)

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o.700, Kaohsiung University Road, anzih District, Kaohsiung City 81148 ， Taiwan (R.O.C.) phone: +886-7-591-9466, fax: +886-7-591-7155

e-mail: [email protected]

Abstract

Aligned Cu

O 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 Cu

O increases with the ratio of H

to N

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.

Room-temperature cathodoluminsecence spectra of the aligned Cu

O porous nanowires exhibit red emissions at 613 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 H

plasma. The enhanced SERS of nanowires after plasma treatment is attributed to improved electrical conductivity and shape effects [1]. 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.

Fig. 1 Plasma treatment-dependent SERS spectra of 4-ABT adsorbed on porous CuxO nanowires recorded using an He-Ne laser at 633 nm as the excitation source.

Acknowledgments

This work was supported by the National Science Council of Taiwan under NSC98-2221- E-390-013-MY2 and NSC98-2221-E-006-082- MY3. The authors also acknowledge the NSC Core Facilities Laboratory for Nano-Science and Nano-Technology in the Kaohsiung-Pingtung area for equipment access and technical support.

References

[1] Y. Badr and M. A. Mahmoud: J. Mol. Struct.

749, 192 (2005).