Photocatalytic properties of in situ doped TiO2-nanotubes grown by rapid breakdown anodization

Abstract

In the present work, we demonstrate an in situ electrochemical doping approach during the growth of TiO₂ nanotubular layers formed by rapid breakdown anodization (RBA). For this, several oxygen containing metal anions, as doping species (WO₄²⁻, Al(OH)₄⁻, SiO₃²⁻, MoO₄²⁻, SnO₄⁴⁻, CrO₄²⁻ and MnO₄⁻), were investigated as additives to the electrolyte and successfully incorporated into the nanotubular oxide during the ultrafast tube growth. A linear relationship between the concentration of anions in the electrolyte and the doping concentration in the oxide was found. The resulting doped layers were tested, after heat treatment, for their UV photocatalytic activity using the degradation of AO7 (an organic model compound routinely used for determining the kinetics of photocatalytic decomposition reactions).