Competition Between Ionic Current and Electronic Current: Regulation of TiO Nanotube Growth.

Titanium dioxide (TiO) nanotubes have been explored for applications in various fields, and their performance is influenced by their length. To investigate the factors affecting the length of anodic TiO nanotubes, samples were fabricated under different applied voltages and in electrolytes with varying poly(ethylene glycol) (PEG) concentrations. The study found that the steady-state current density in the current density-time curve exhibits a strong linear relationship with nanotube length. High PEG concentrations lead to a significant reduction in nanotube length (Compared to the electrolyte containing 25 wt % PEG, the nanotube length obtained in the electrolyte containing 75 wt % PEG was reduced by 82.0%.). From the perspectives of ionic current and electronic current, high concentrations of PEG suppress electronic current, reducing oxygen generation. This leads to a decrease in nanotube length and an increase in wall thickness, even resulting in nanotubes with closed tops. These results indicate that nanotube length is not related to the field-assisted dissolution rate. Instead, it depends on the ionic current density and electronic current density during anodization.