Anodized Aluminum Oxide Films as Nanostructured Template for the Grow of Carbon Nanotubes
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Anodized Aluminum Oxide Films as Nanostructured Template for the Grow of Carbon Nanotubes Y.C. Sui*, J.A. González-León*, A. Bermúdez*, D.R. Acosta#, J. Feuchtwanger*, J.O. Flores*, B.Z. Cui*, M.E. Mata-Zamora* and J.M. Saniger*. Universidad Nacional Autónoma de México, Apdo-Postal 70-186 México D.F. (*)Centro de Instrumentos, Laboratorio de Materiales y Sensores; (#)Instituto de Física
ABSTRACT A summary of our recent work related to the growth of carbon nanotubes (CNTs) inside the pores of anodized alumina oxide (AAO) films is presented. The surface topography of the AAO film was studied by atomic force microscopy, while the internal pore structure of the AOO templates was concluded from the shape of the CNTs obtained. The effect of the different experimental approaches and of the anodization voltage value on the features of the pores and CNTs is also discussed, as well as the catalytic effect in the acetylene pyrolysis of the Co particles and internal alumina walls. The CNTs wall structure observed by HRTEM and its implication on some physico-chemical properties of the CNTs are also presented.
INTRODUCTION Electrochemical anodization of aluminum surfaces is normally accomplished in acidic media. When the acid used is unable to dissolve the aluminum oxide a smooth and continuous oxide film surface is obtained; otherwise, a porous surface with a variable porous arrangement is obtained. In fact, anodized aluminum oxide (AAO) films when grown in the appropriate acid electrolyte possess regular and highly anisotropic porous structure with pore diameter ranging from 5 to about 100 nm, and with a density of pores ranging from 109 to 1011/cm2. These characteristics allow a certain capability for the design of the pore features making the porous AAO templates an interesting substrate for nanotechnological applications. In fact, it has been used for the growth of bundles of aligned carbon nanotubes, metallic nanowires, semiconductor nanorods, etc., [1-9] potentially useful for the development of electronic and electrooptical nanodevices In this work a summary of our experiences and findings in the growth of CNT in porous AAO films is presented. It should be remarked that this experiments have allowed us to reach a double objective, the use of porous AAO films for arranging CNTs bundles and, on the other hand, the use of CNTs as casts for the characterization of the internal shape of the AAO pores. The effect of the anodization voltage on the internal shape of the pores and then, on the shape of the casting CNTs is presented. The growth of CNTs inside the AAO templates with and without the deposition of Co particles at the bottom of the pores is also discussed. Finally, the poor crystalline structure of the CNTs walls, when compared with those obtained by the arc discharge technique, and its influence on their thermal and mechanical properties is also analyzed.
A13.51.1
EXPERIMENTAL DETAILS Porous AAO films were obtained from metallic Al discs (Aldrich, 99.999%) mechanically and electrochemically polished (room tempera
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