Synthesis and characterization of TiO2 doped with P ions by anodic oxidation of titanium in acid solution

Abstract

In this paper, the synthesis of TiO2 films and simultaneous P ion-doping for them were attempted by the anodic oxidation of titanium in phosphoric acid solution under various conditions (several concentrations of phosphoric acid solution and applied voltages on the anodic oxidation etc). Products obtained by this anodic oxidation of titanium were thin films and attached firmly to the surface of titanium. Although the surface of the oxide film obtained by an anodic oxidation in 0.25 M phosphoric acid at 350 V was flat, their oxide films were consisted of fine particles of 20-50 nm in diameter and had the unidirectional pores with the pore of about 200 nm to 1 μm in diameter. From XPS results, P5+ ions were mainly doped near the surface of the oxide film, although P ions were existed as P3+ inside the TiO2 films, suggesting the successful doping of P ions, such as P5+ and P3+ into the TiO2 films. Therefore, this anodic oxidation processing is useful for synthesis of TiO 2 films and simultaneous doping of P ions, leading to the development of a useful vector processing from an electro-chemical vector effect.