Photocatalytic activity of reduced TiO₂ nanotube arrays on silicon substrate

TiO₂ nanotube (TiNT) arrays were grown on silicon substrate via electrochemical anodization of titanium films sputtered by magnetron. To improve their photocatalytic activity reduction in H2/Ar was used. Investigation of composition and morphology by X-ray diffraction (XRD), electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) showed the presence of well-ordered arrays of anatase nanotubes with average diameter and length of 100 nm and 1.3 μm, respectively. Reduced TiNT exhibited higher rates in the photodegradation of organic dyes (compared to oxidized TiNT) and this is caused by limitation of electron-hole recombination rates by a shift of the energy gap into visible region. The photocatalytic activity was measured under UV, sunlight and visible irradiation. (authors)