Nitrates: A new class of electrolytes for the rapid anodic growth of self-ordered oxide nanopore layers on Ti and Ta

In the present work, we demonstrate that anodization in a nitrate containing organic electrolyte, under specific conditions, can be used to achieve highly aligned nanoporous oxide layers on Ti and Ta substrates. These layers after formation consist of amorphous TiO₂ and Ta₂O₅, respectively, with regular pore sizes in the range of 20 to 30 nm. The amorphous layers can easily be crystallized by annealing. A main geometric feature of the layers is that they show a through-hole morphology which is considered to be of high interest for various types of membrane applications.