Fabrication of iron oxide nanotube arrays by electrochemical anodization

•Oriented and smooth iron oxide nanotube arrays were synthesized by anodization.•Anodization parameters strongly affect the oxide morphology of the anodic oxidation.•A model is proposed to explain the formation mechanism of oxide during anodization.

Highly ordered iron oxide nanotubes with smooth and homogeneous wall were electrochemically synthesized by potentiostatic anodization of iron foil in an ethylene glycol based electrolyte containing NH4F and deionized water at 60 °C. A model was proposed to explain the formation mechanism. The effects of anodization conditions, such as potential, H2O concentration, NH4F concentration, temperature and thermal treatment, on morphology and structural features of the oxide layer were thoroughly investigated. It is shown that the current transient curve can be used as a tool to approximately predict the morphology and the formation of nanotube during the anodization of iron.