Historical Analysis and Applications of Nanoporous Anodized Aluminium Oxide

Abstract

Anodic oxidation is one of the advantageous techniques used to form a thicker oxide on the surface of aluminium. The history of anodization of aluminum dates back to the beginning of the last century. Several patents had been published before the 1950’s, relating to the anodization of aluminum for decorative and coloring purposes. Anodized aluminium has pores and it is probable to generate self organized nanopores in this oxide layer by controlled anodization process. The remarkable characteristics of nanoporous anodic alumina such as highly orderings, large and small pore diameter, high pore density and longer pore channel length or thickness give marvellous results in engineering applications. For instance highly ordered and having large diameter nanopores of anodic aluminium oxide (AAO) enhances electrical, optical, and photoelectric properties. A leading example is the fabrication of ordered metallic nanowires by using AAO template, those can be applied to lithium ion batteries, magnetic devices, energy storage devices, solar cells and nano-reactors. However, high density followed by smaller-sized nanopores of AAO is crucial to enhance infiltration, ion transportation, molecular separation and catalysis. Furthermore, longer pore channel length or thickness enhances chemical resistance and adsorption properties. This property makes the surface wear resistant, corrosion resistant and suitable for load bearing applications which proves as a boon for triblology. The aim of present paper is to review on versatile applications of nanoporous anodized aluminium oxide template (NPAAO).