Nanowire and Nanotube Syntheses Through Self-assembled Nanoporous AAO Templates
- PDF / 1,489,917 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 83 Downloads / 173 Views
P4.8.1
Nanowire and Nanotube Syntheses Through Self-assembled Nanoporous AAO Templates H. Hau Wang,* Catherine Y. Han, Gerold A. Willing, and Zhili Xiao Materials Science Division, Argonne National Laboratory, Argonne, IL 60439 ABSTRACT Nanowires and nanotubes have attracted significant interest during recent years due to their novel electrical, magnetic, and photonic properties. Quantum confinement, proximity interaction, and surface plasmon enhancement effects are among a few unique phenomena associated with these materials. A convenient procedure to prepare these materials is through anodized aluminum oxide (AAO) template synthesis. Nanoporous AAO membranes with pore diameters ranging from 10 to 200 nm can be prepared with anodization in oxalic, sulfuric and phosphoric acids under various reaction conditions. With repeated anodization-etching cycles, highly ordered straight channels can be prepared through self-organization. With electro- and electroless deposition, a variety of nanowires and nanotubes such as Ni, Co, Au, Pb, Bi, etc. have been prepared. The synthesis, characterization, and physical properties of these materials are presented.
INTRODUCTION Nanoscale synthesis and fabrication has attracted much interests during recent years. Part of the reasons is the trend toward perpetual device miniaturization and part of the reasons is the new phenomena that can be probed with confined sizes in the nanometer region such as quantum confinement effects and proximity interactions between superconductivity and ferromagnetism. Many different synthetic strategies have been devised for the fabrication of nanoscaled species, such as the use of surfactants, micelles, and reverse micelles to prepare nanoparticles [1], the use of block copolymers to prepare nanoporous materials as well as nanodots and nanorods [2], the use of colloidal solutions to prepare photonic lattices [3], etc. Most of these techniques are bottom-up approaches and depend upon molecular self-assembly. In this article, we will focus on nanoscale synthesis through the use of anodized aluminum oxide (AAO) templates [4]. The AAO templates consist of straight nanopores arranged in a hexagonally close packed pattern. The formation mechanism is through self alignment. The resulting nanoporous AAO membranes have been used for size selective filtration, protective surface coating, catalyst support, etc. Our interest is to utilize AAO membranes to prepare highly uniform nanowires, nanotubes, masks for lithographic purpose, etc.
EXPERIMENTAL AAO membranes are prepared with high purity aluminum sheets (99.998%) through anodization in aqueous solutions. Typical steps involve the following: 1. Cleaning, degreasing, and mechanical polishing; 2. Annealing at 500 °C under argon atmosphere for 4 hours to enhance the grain size; 3. Electropolishing in a solution of HClO4 (60 wt%) and EtOH (1:8 in
Downloaded from https://www.cambridge.org/core. Columbia University Libraries, on 19 Jul 2017 at 12:33:05, subject to the Cambridge Core terms of use, available at https:
Data Loading...
