Titanate nanotubes (TNT) were prepared via a hydrothermal treatment of synthesized TiO2 powders in a 10 M NaOH solution at 130◦C for 24 h and subsequently washed with HCl aqueous solution of different concentrations (with water only, 0.01, 0.1 and 1 M). Samples with different contents of remnant sodium in nanotubes after heat-treatment were characterized, by high resolution transmission electron microscopy, X-ray diffraction, fourier transform infrared spectroscopy and Raman spectroscopy. The photocatalytic activity of TNT was evaluated by photocatalytic oxidation of phenol in water solution. Highly remnant sodium in nanotubes has a detrimental effect on the photocatalytic activity of titanate. This is attributed to the high concentration sodium preventing formation of the photoactive anatase phase and low concentration sodium producing surface and bulk recombination centers of photogenerated electron-hole pairs.
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