Room temperature one-step synthesis of microarrays of N-doped flower-like anatase TiO₂ composed of well-defined multilayer nanoflakes by Ti anodization

Microarrays of N-doped flower-like TiO₂ composed of well-defined multilayer nanoflakes were synthesized at room temperature by electrochemical anodization of Ti in NH₄F aqueous solution. The TiO₂ flowers were of good anatase crystallinity. The effects of anodizing time, applied voltage and NH₄F concentration on the flower-like morphology were systematically examined. It was found that the morphologies of the anodized Ti were related to the anodizing time and NH₄F concentration. The size and density of the TiO₂ flowers could be tuned by changing the applied voltage. The obtained N-doped flower-like TiO₂ microarrays exhibited intense absorption in wavelengths ranging from 320 to 800nm. Under both UV and visible light irradiation, the photocatalytic activity of the N-doped flower-like TiO₂ microarrays in the oxidation of methyl orange showed a significant increase compared with that of commercial P25 TiO₂ film.