Review on fabrication, characterization, and applications of porous anodic aluminum oxide films with tunable pore sizes for emerging technologies

Anodizing aluminum allowed the production of one-of-a-kind porous anodic aluminum oxide (PAAO) films. These films have a perfectly flat barrier layer and an exceedingly porous structure. Because of its one-of-a-kind optical and electrochemical properties, large surface area, tunable properties, and high thermal stability, nanoporous anodic aluminum oxide (AAO) has become one of the most popular materials with an enormous potential to develop emerging applications in a variety of fields. These fields include biosensors, desalination, high-risk pollutants detection, capacitors, solar cell devices, photonic crystals, template-assisted fabrication of nanostructures, and other similar fields. This article discusses the process behind the development of AAO, the manufacturing method, the link between the characteristics of AAO and the fabrication circumstances, as well as the applications of AAO. Fabrication circumstances, such as electrolyte, applied voltage, anodizing, and widening time, may completely influence the properties of AAO, such as pore diameter, interpore distance, wall thickness, and the thickness of the anodized aluminum layer. The pore diameter of AAO will have a significant impact on the application that it is used for. In addition, production techniques such as one/two/multi-step anodization, nanoimprint lithography anodization, and pulse/cyclic anodization all have a significant influence on the final array layout. This paper aims to offer a perspective overview of the systematic link between applications and the AAO pore sizes that correspond to those applications. In addition to this, the study concentrates on the many methods through which the AAO's various structures and functions may be used.