Delivered by Ingenta to: University of South Australia IP : 95.27.0.201 Wed, 04 Jul 2012 14:23:30 Copyright © 2010 American Scientific Publishers All rights reserved Printed in the United States of America Science of Advanced Materials Vol. 2, 295–335, 2010 Synthesis of TiO 2 and CuO Nanotubes and Nanowires Dinesh Pratap Singh * and Naushad Ali Department of Physics, Southern Illinois University Carbondale, Carbondale, IL, 62901, USA Nanowires, nanotubes, nanobelts, nanoribbons, nanorods etc. are a new class of quasi-one- dimensional materials that have been attracting a great research interest since last few years. In the words of David Appell “Nanowires, nanorods or nanowhiskers. It doesn’t matter what you call them, they’re the hottest property in nanotechnology.” These nanomaterials have been proposed as important components of electronic and optoelectronic nanodevices and are expected to play an integral part in the design and construction of these devices. Among these nanostructures, compound semiconductor nanowires and nanotubes are attracting more and more attention due to their great potential applications in nanodevices. Apart from ZnO, TiO 2 and CuO semiconductors have attracted considerable attentions due to their wide applications in enormous area of research. Titanium dioxide, due to its specific semiconductive properties, has been a highly investigated material for a plethora of applications, such as solar cells, photocatalysis, hydrogen production, self-cleaning coatings or purification of water and air. Simileraly As a p-type semiconductor with a narrow bandgap (1.4 eV), CuO has been extensively studied because an important component of copper oxide superconductors, a powerful heterogeneous catalyst, magnetic storage media, solar energy transformation, field emission and gas sensors. Due to their high aspect ratio one dimen- sional nanomaterials of these oxides have a superior property in all related areas.Various methods have been adopted for the synthesis of one dimensional nanowires and nanotubes of TiO 2 and CuO. Among these electrochemical based anodization for TiO 2 nanotubes and copper based ther- mal oxidation for CuO nanowires have been widely studied. This review covers various synthetic strategies adopted so far, for the synthesis of TiO 2 and CuO nanotubes and nanowires. Keywords: TiO 2 Nanotubes, Template Based, Template Free, CuO Nanowires, Thermal Oxidation. CONTENTS 1. Introduction ........................................ 295 2. Synthesis of TiO 2 Nanotubes and Nanowires .............. 296 2.1. Types of TiO 2 .................................. 297 2.2. Template Method ................................ 297 2.3. Template Free Method ............................ 317 3. Synthesis of CuO Nanorods ........................... 322 3.1. By Thermal Oxidation of Copper Sheet ............... 323 3.2. Hydrothermal Method ............................ 325 3.3. Wet Chemical Method ............................ 328 4. Conclusion ........................................ 331 Acknowledgment .................................... 331 References and Notes ................................ 331 1. INTRODUCTION One-dimensional nano-materials have attracted a plenty of attention in recent years. 1–4 These nano-structured materials not only have theoretical importance in physi- cal phenomena related to quantum confinement, but also * Author to whom correspondence should be addressed. provide a strong potential application. One-dimensional nanostructures, such as nanowires nanobelts, nanoribbons, nanorods and nanotubes, represent the smallest dimen- sion for efficient transport of electrons and excitons and thus are ideal building blocks for hierarchical assem- bly of functional nanoscale electronic and photonic struc- tures. Depending on what it’s made from, a nanowire can have the properties of an insulator, a semiconductor or a metal. These non-carbon based materials have been demon- strated to exhibit superior electrical, optical, mechanical and thermal properties, and can be used as fundamen- tal building blocks for nano-scale science and technol- ogy, ranging from chemical and biological sensors, field effect transistors to logic circuits. Nanocircuits built using semiconductor nanowires demonstrated were declared a “breakthrough in science.” 5 6 The term ‘nanowire’ is gen- erally used to describe a large aspect ratio of 1–100 nm in diameter. Both descriptors are pertinent to the physi- cal and technological significance of nanowires. First, the diameter puts the radial dimension of these structures at Sci. Adv. Mater. 2010, Vol. 2, No. 3 1947-2935/2010/2/295/041 doi:10.1166/sam.2010.1095 295