Morphology evolution of TiO2 nanotubes with additional reducing agent: Evidence of oxygen release

Abstract

In order to explore wider application of porous anodic alumina and anodic TiO2 nanotubes (ATNTs), the formation mechanism research of porous anodic materials plays a more significant role. Traditional field-assisted dissolution theory has been put into question and oxygen bubble mold has been accepted gradually. However, it is difficult to prove oxygen release. In this work, we present a method to demonstrate the presence of oxygen in the pores of nanotubes. A kind of water soluble reducing agent (NH4H2PO2) was added into electrolyte containing NH4F. Cavities exists not only between the double walls of nanotubes but also in the inner walls, which are different from normal nanotubes. The morphology evolution of nanotubes results from the reaction between NH4H2PO2 and oxygen. Therefore, the release of oxygen during the formation of ATNTs was further proved.